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What Is the Beam on a Boat? (Fully Explained)

Written by J. Harvey / Fact checked by S. Numbers

What is the beam on a boat ? It refers to the entire breadth of the vessel, with the widest distance between the hull’s gunwales or the port and starboard sides as the main points of reference. This is the simplest beam boat meaning.

If you want a broader definition that will expound on other considerations like beam overall, beam waterline, and beam centerline, then continue reading. You’ll also learn how to measure it and why it’s necessary for navigation and determining the direction of and from the vessel.

Table of Contents

Boat Beams Defined in Detail

How to measure the beam of a boat, how does the width of the beam impact a boat’s or ship’s performance, the role that the beam of a boat plays in nautical navigation, not to be confused with the “other” beams on a boa.

Since not all marine vessels are the same when it comes to design, it’s better to stick to the more general definition that it’s the widest distance between starboard and port.

For instance, it’s still valid for a boat owner to measure the breadth of a sailboat beam by using the windshields as the reference, instead of the gunwales. Why? Because, in the end, we’re more concerned with the widest point of the vessel when measuring the beam.

This definition only connotes the Beam Overall (BOA, in short) though. It’s just as important to dive into other considerations (usually related to measurements) connected to it such as the following:

• Beam Waterline

This refers to the width of the hull relative to the ship’s waterline. If you’re not already aware of it, the waterline connotes the point of intersection between the water surface and the sides of a vessel’s hull.

• Beam Centerline

This only applies to multihulls and refers to the distance between the vessel’s respective hulls.

A good, old tape measure will do for getting the exact boat beam measurement. Simply run it from the farthest side of the port to the starboard point that is parallel to it, and you’ll get the accurate beam measurement on a boat.

How can you be sure that you’re measuring the widest part of your boat? You can use your vessel’s line as a point of reference by using the method expounded on this site.

Ultimately, you’ll have to rely on estimations that will only be supported by using the tape measure method. When all is said and done, it’s infinitely better to just rely on a marine surveyor to take the measurement for you.

Once you get the hang of what it’s like to sail in the open sea, you’ll realize the perks of having a wider marine beam. For one, the wider or lengthier a ship gets, the more stability it enjoys – although more width often means lesser efficiency.

Certain boat makers actually design their vessels with that in mind to help them resist major stability issues like capsizing. Since both length and width are important, boatbuilders meticulously pay attention to the ideal beam to length ratio.

• The classical ratio of 3:1 is generally considered safe and solid. However, slight deviations of 4:1 or even 5:1, as evidenced by certain types of monohulls, won’t hurt.

Are you familiar with wide beam boats or widebeams as some folks in the UK refer to them? They are arguably the best example of how much beam width on a boat can impact a vessel’s perks.

For one, not only are they generally more stable, but almost anyone who has owned them or ridden in them can say that they enjoy the spacious decks that they can accommodate. “Precious real estate” is undoubtedly a phrase that gets used a lot when boat owners discuss their vessels, highlighting the importance of space in most boats and ships.

Much like how you have to be familiar with port and starboard for navigating a vessel, you should also familiarize yourself with the importance of other parts and sections. Did you know that the beam is equally vital for it?

For instance, the port beam and starboard beam are often used as points of reference.

• For example, an object, vessel, or location from the ship that is positioned at exactly 90 degrees right or left of the vessel’s head may be referred to as being spotted from the starboard beam or port beam respectively.

You might also encounter seamen using the phrase “abaft or astern the starboard beam or port beam” or “forward the port beam”. Abaft or astern only means it’s slightly behind the beam while forward connotes heading toward the head or dead ahead.

The following illustration provides a good overview of what I’ve explained above. As you can see, the first example has been encircled and represented by slanting lines to highlight its direction relative to the beam’s position.

During the latter part of the Age of Sail when pirates still plagued the high seas, ships usually had large steel or wooden beams that run athwartship. They serve highly reliable purposes both as strength members and as an effective way to trap pirates at the same time.

Sailors used to mark the main beam as the queen beam for the latter purpose. Take note that some ships still practice this, even if they already have big steel beams but they use a welding rod to mark them instead.

The fact that there are two types of it on a boat may readily create confusion as to what a beam mean on a boat, right? With that said, it’s important for any sailor to know the distinction between the actual beam of a ship and these deck-reinforcing members.

So let’s sum up our answer to “What is the beam on a boat?” It’s the widest part of a boat or ship, which, in turn, plays a pivotal role in determining its stability and storage space, and it offers referential perks for optimal maritime navigation.

If you want to make sure that your vessel is optimally stable, always take the time to measure the beam of a boat. Moreover, I hope that by adding clarificatory information here, people will finally be able to figure out what a beam means on a boat.

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What Is Boat Beam? Understanding the Basics of Boat Beam Measurement

Boat beam, also known as the width or breadth of a boat, is an essential measurement in the design and construction of a vessel. Understanding boat beam is critical for anyone looking to purchase, operate, or design a boat.

This article will provide an overview of boat beam and its importance, discuss the different types of boat beams, explore how boat beam is measured, and examine the factors affecting boat beam dimensions. We’ll also look at the relationship between boat beam and stability, as well as regulations and standards governing boat beam dimensions. So, let’s dive in and learn about boat beam measurement!

Quick Facts

Defining Boat Beam: An Overview

In simple terms, boat beam refers to the width of a boat at its widest point. It is measured from the outer edge of the hull on one side to the opposite side. Some boats have a straight-line beam measurement, while others have a curved or angled measurement due to different hull designs. Boat beam is an important measurement for boats of all sizes, from small dinghies to large cruise ships. It has a direct impact on a boat’s handling, stability, and performance.

Importance of Boat Beam in Vessel Design

Boat beam plays a crucial role in the overall design and performance of a boat. A wider beam can offer increased stability, carrying capacity, and overall comfort for passengers and crew. However, a wider beam can also mean greater draft and windage, which can impact maneuverability and speed. It’s essential to strike a balance between width and performance, taking into account the intended use of the boat.

When designing a boat, naval architects consider a wide range of factors, including the intended use of the vessel, the materials used in construction, and the desired performance characteristics. Boat beam is just one of many factors that must be taken into account.

For example, a fishing boat designed for use in rough seas may require a wider beam to provide greater stability and prevent capsizing. On the other hand, a racing sailboat may require a narrower beam to reduce drag and increase speed.

Boat beam can also impact the interior layout and design of a vessel. A wider beam can allow for more spacious cabins and living areas, while a narrower beam may require a more compact layout.

Different Types of Boat Beams

There are several types of boat beams, each with unique characteristics and applications:

• Transom beam – This is the width of the boat at the transom, or the aft end of the boat. It is an essential measurement for determining the boat’s overall stability.
• Waterline beam – This measurement is taken at the boat’s waterline, which is the level at which the boat sits in the water. It is crucial for stability calculations and determining the boat’s load capacity.
• Maximum beam – This measurement is taken at the widest point of the boat, typically where the hull flares out. It is essential for determining the boat’s maneuverability and handling characteristics.

Understanding the different types of boat beams is important for anyone involved in boat design, construction, or maintenance. Each type of beam can provide valuable information about a boat’s performance and characteristics, helping to ensure that the vessel is safe, stable, and seaworthy.

How Boat Beam Measurement Works

Measuring boat beam is an important step in ensuring your boat is safe and seaworthy. The beam of a boat refers to its width at its widest point, which is typically near the middle of the boat. Here are some additional details about how boat beam measurement works:

• Flexible or Rigid Measuring Tapes: When using a flexible measuring tape, it’s important to ensure that the tape is taut and straight to obtain an accurate measurement. Rigid measuring tapes are often used for larger boats, as they provide more stability and precision.
• Laser Scanning Technology: This technology uses lasers to create a 3D image of the boat, which allows for highly accurate measurements of the beam.
• Ultrasonic Sensors: These sensors use sound waves to measure the distance between two points on the boat’s hull, which can be used to calculate the beam.
• Optical Sensors: Optical sensors use light to measure the distance between two points on the boat’s hull, which can also be used to calculate the beam.

It’s important to note that the accuracy of boat beam measurements can be affected by factors such as the shape of the boat’s hull, the presence of any obstructions or protrusions, and the conditions in which the measurement is taken.

Tools and Techniques for Measuring Boat Beam

While flexible and rigid measuring tapes are the most common tools used to measure boat beam, laser scanning technology is becoming increasingly popular due to its high level of accuracy. Ultrasonic and optical sensors are also used in some cases, particularly for larger boats where it may be difficult to obtain an accurate measurement using a tape measure.

Standard Units of Measurement

Boat beam measurements are typically expressed in feet, inches, or meters. In the United States, feet and inches are the most commonly used units, while meters are often used in other parts of the world. It’s important to use standardized units of measurement to ensure accuracy and consistency across boat measurements. When measuring boat beam, it’s also important to take into account any local regulations or requirements regarding boat dimensions.

Factors Affecting Boat Beam Dimensions

Several factors influence boat beam dimensions, including hull shape and design, boat size and purpose, and material and construction.

Boat builders must carefully consider these factors when designing and constructing a boat to ensure that it meets the intended purpose and performs optimally.

Hull Shape and Design

The shape and design of a boat’s hull can have a significant impact on its beam dimensions. A boat with a wider hull will usually have a wider beam, while boats with more rounded or tapered hulls will have narrower beams. However, the hull shape and design also affect other important aspects of boat performance.

For example, a flat-bottomed hull with a wide beam will provide greater stability and buoyancy, making it ideal for larger boats that carry heavy loads. On the other hand, a V-shaped hull with a narrower beam will cut through the water more efficiently, providing better speed and maneuverability for smaller boats.

Another important consideration is the deadrise angle, which refers to the angle at which the hull meets the waterline. A greater deadrise angle will provide a smoother ride in rough waters but may also increase beam dimensions to maintain stability.

Boat Size and Purpose

The size and intended purpose of a boat also affect beam dimensions. Larger boats designed for cruising or commercial use typically have wider beams to accommodate more passengers or cargo. This allows for a more spacious interior and greater stability when carrying heavy loads.

In contrast, smaller boats, such as dinghies or kayaks, will have narrower beams for increased speed and maneuverability. A narrow beam allows for easier handling and better performance in tight spaces.

The intended purpose of the boat also affects beam dimensions. For example, a fishing boat may have a wider beam to provide more stability when casting, while a racing sailboat will have a narrower beam to increase speed and agility.

Material and Construction

The materials and construction methods used in building a boat can also impact beam dimensions. Boats made from heavier materials such as steel or fiberglass might have wider beams to support the weight, while boats made from lighter materials like aluminum or carbon fiber might have narrower beams to increase speed and agility.

The construction method can also affect beam dimensions. Boats built using traditional methods, such as wooden planking, may have wider beams to maintain structural integrity. In contrast, boats built using modern techniques, such as vacuum infusion, may have narrower beams due to the increased strength of the materials used.

Ultimately, boat builders must carefully consider all of these factors when designing a boat to ensure that it meets the intended purpose and performs optimally. By taking into account hull shape and design, boat size and purpose, and material and construction, boat builders can create vessels that are both functional and aesthetically pleasing.

The Relationship Between Boat Beam and Stability

Boat enthusiasts know that the beam of a boat is a crucial factor in determining its stability and handling. The beam refers to the width of the boat at its widest point, which is typically near the middle of the vessel. A wider beam generally means greater stability, as it provides more surface area for the boat to rest on the water. However, wider beams can also make a boat slower and less maneuverable. It’s important to find the right balance between width and performance for safe and comfortable boating.

How Wider Beams Contribute to Stability

Wider beams contribute to stability in several ways:

• Greater surface area – Wider beams provide a larger surface area for a boat to rest on the water, which can significantly increase stability in rough or choppy conditions. This is particularly important for larger boats, which can be more susceptible to rocking and rolling in the water.
• Lower center of gravity – A wider beam can lower a boat’s center of gravity, which can improve stability and reduce the risk of capsizing or flooding. This is because a wider beam allows for more weight to be distributed horizontally across the boat, rather than being concentrated in the center.
• Increased carrying capacity – A wider beam can also increase a boat’s carrying capacity, as it provides more space for passengers and cargo. This can be particularly useful for commercial vessels or boats used for fishing or other activities that require a lot of gear.

Limitations and Trade-offs of Wider Beams

While wider beams can contribute to stability, there are limitations and trade-offs to consider:

• Draft – A wider beam can lead to a deeper draft, which can limit the boat’s ability to navigate in shallow waters. This can be a problem for boats that need to navigate in areas such as rivers, estuaries, or coastal inlets.
• Windage – Wider beams can also increase windage, or the amount of surface area exposed to the wind, which can adversely affect the boat’s speed and maneuverability in windy conditions. This can be particularly problematic for sailboats, which rely on wind power to move.
• Maneuverability – Wider beams make a boat less maneuverable, particularly in tight spaces or narrow channels. This can make it difficult to dock or navigate in crowded marinas or other areas with limited space.
• Cost – Finally, wider beams can also increase the cost of a boat, as they require more materials and labor to construct. This can be a significant factor for people who are on a tight budget or looking for a more affordable option.

Overall, the relationship between boat beam and stability is a complex one, with many factors to consider. While a wider beam can increase stability and carrying capacity, it can also lead to trade-offs in terms of maneuverability, draft, windage, and cost. Ultimately, the right beam width will depend on the specific needs and preferences of the boat owner, as well as the type of boating they plan to do.

Boat Beam Regulations and Standards

Boat beam regulations and standards exist to ensure the safety and performance of boats. The International Maritime Organization (IMO) sets global guidelines for boat beam dimensions, while national and regional regulations also apply.

International Maritime Organization (IMO) Guidelines

The IMO sets standards and guidelines for all types of boats. Their guidelines for boat beam dimensions depend on the boat’s type and size. For example, a boat over 24 meters in length must have a beam of at least 80% of its waterline length.

National and Regional Regulations

Many countries and regions have their own regulations and standards governing boat beam dimensions. These regulations vary widely depending on the type and size of the boat, as well as its intended use.

Boat beam is a critical measurement in boat design, construction, and operation. This article has provided an overview of boat beam and its importance, discussed the different types of boat beams, explored how boat beam is measured, and examined the factors affecting boat beam dimensions.

We’ve also looked at the relationship between boat beam and stability, as well as regulations and standards governing boat beam dimensions. By understanding boat beam, how it is measured, and what factors affect its dimensions, boaters can make informed decisions about boat design, purchase, and operation.

Boat Beam FAQS

What is the beam of a ship called.

The beam of a ship, also known as the breadth, refers to the widest point of the ship. It’s measured from one side of the ship to the other at its broadest part.

What is boat beam measurement?

Boat beam measurement is the process of measuring the width of a boat at its widest point. It’s measured from the outer edge of the hull on one side to the opposite side. Various techniques can be used for this measurement, including flexible or rigid measuring tapes, laser scanning technology, ultrasonic sensors, and optical sensors.

What is the purpose of a beam on a ship?

The beam of a ship serves several crucial roles. It directly impacts the ship’s stability, handling, and performance. A wider beam can offer increased stability, carrying capacity, and overall comfort for passengers and crew. However, a wider beam can also increase draft and windage, which can impact maneuverability and speed.

What is beam in naval terms?

In naval terms, the beam refers to the maximum width of a vessel. This measurement is used in designing and constructing the vessel and impacts the vessel’s stability, capacity, and performance.

Where is the beam of a boat?

The beam of a boat is located at its widest point, usually around the middle of the boat. It is measured from the outer edge of the hull on one side to the opposite side.

Do ships have beams?

Yes, all ships have beams. The beam is a fundamental aspect of a ship’s design and impacts its overall stability, capacity, and performance. It’s a critical measurement that plays a significant role in the ship’s design, construction, and operation.

John is an experienced journalist and veteran boater. He heads up the content team at BoatingBeast and aims to share his many years experience of the marine world with our readers.

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What is the Beam of a Boat? A Clear Explanation

The beam of a boat is a critical measurement that determines the width of the vessel at its widest point. It is an essential factor in the design and construction of a boat, as well as in its performance and stability on the water.

The beam is measured from the outer edge of the port side to the outer edge of the starboard side, and it is usually expressed in feet or meters.

Understanding boat beam is crucial for anyone looking to purchase, operate, or design a boat. The beam of a boat plays a significant role in its stability, maneuverability, and performance.

A wider beam generally makes a boat more stable, but it can also make it slower and less maneuverable. On the other hand, a narrower beam can make a boat faster and more maneuverable, but it can also make it less stable. Therefore, finding the right balance between beam and other factors, such as length, draft, and weight, is essential in designing and building a seaworthy vessel.

Key Takeaways

• The beam of a boat is the width of the vessel at its widest point, measured from the outer edge of the port side to the outer edge of the starboard side.
• Boat beam is a critical factor in a vessel’s stability, maneuverability, and performance, and finding the right balance between beam and other factors is essential in designing and building a seaworthy boat.
• A wider beam generally makes a boat more stable, while a narrower beam can make it faster and more maneuverable, but less stable.

Understanding Boat Beam

The boat beam is an essential aspect of a boat’s design that determines its stability in the water. In nautical terms, a boat beam is the overall width of a boat, measured at the widest point of the nominal waterline. The wider the beam, the more stable the boat, while a narrower beam can make the boat less stable.

The boat beam is measured from the outer edge of the hull on one side to the opposite side. Some boats have a straight-line beam measurement, while others have a curved or angled measurement due to different hull designs . The maximum beam is the widest point of the boat, which is typically located amidships.

The boat beam is closely related to the hull shape, which plays a significant role in determining the boat’s stability, speed, and maneuverability. The wider the beam, the flatter the hull shape can be, which results in better stability. In contrast, a narrow beam requires a deeper V-shaped hull to maintain stability, which can result in a slower speed.

The boat beam is also related to the centerline, which is an imaginary line that runs from the bow to the stern, dividing the boat into two equal halves. The beam is measured perpendicular to the centerline, from one gunwale to the other. Gunwales are the upper edges of the boat’s sides , and they are often used as a reference point for measuring the beam.

In summary, a boat beam is the overall width of a boat, measured at the widest point of the nominal waterline. It is closely related to the hull shape, centerline, and gunwales. The wider the beam, the more stable the boat, while a narrower beam can make the boat less stable. Understanding boat beam is crucial for selecting the right boat for a specific purpose and ensuring safe and enjoyable boating experiences.

Importance of Beam in Boat Stability

The beam of a boat plays a crucial role in determining its stability on the water. The beam is the widest point of the boat, and it affects the boat’s handling characteristics. A narrow beam allows the boat to go faster, while a wider beam provides more stability.

The stability of a boat is essential for safe navigation on the water. The beam affects the boat’s stability by determining its center of gravity. A boat with a wider beam has a lower center of gravity, which makes it more stable. This stability is crucial to prevent the boat from capsizing.

Capsize is a significant concern for any boat operator. A boat with a narrow beam has a higher risk of capsizing, especially in rough waters. The wider beam of a boat provides more secondary stability, which helps to keep the boat upright in challenging conditions.

The deadrise of a boat is the angle between the hull’s bottom and the waterline. The beam affects the deadrise, which in turn affects the boat’s stability. A boat with a wider beam typically has a flatter bottom, which provides more stability.

In summary, the importance of the beam in boat stability cannot be overstated. The beam affects the boat’s handling characteristics, center of gravity, secondary stability, and deadrise. Boat operators must consider the beam when choosing a vessel to ensure safe navigation on the water.

Beam Measurement Techniques

Measuring the beam of a boat is a critical aspect of boat design and construction. It is necessary to ensure that the boat is safe and stable on the water. There are several techniques for measuring the beam of a boat. Here are some commonly used techniques:

• Measuring Tape: Measuring tape is the most commonly used tool for measuring the beam of a boat. It is a flexible tape that can be wrapped around the widest point of the boat’s hull. The measurement is then taken from the outer edge of the hull on one side to the opposite side.
• Tape Measure: A tape measure is another tool that can be used to measure the beam of a boat. It is a rigid tape that can be extended to the widest point of the boat’s hull. The measurement is then taken from the outer edge of the hull on one side to the opposite side.
• Marine Surveyor: A marine surveyor is a professional who specializes in inspecting and evaluating boats. They use specialized equipment and techniques to measure the beam of a boat. They may use ultrasonic equipment to measure the thickness of the hull and determine the beam of the boat.

Regardless of the technique used, it is important to ensure that the measurement is accurate. The beam of a boat is a critical factor in determining its stability and safety on the water. A small error in measurement can have significant consequences.

In conclusion, measuring the beam of a boat is an essential aspect of boat design and construction. There are several techniques available for measuring the beam of a boat, including measuring tape, tape measure, and marine surveyor. It is important to ensure that the measurement is accurate to ensure the safety and stability of the boat on the water.

Impact of Beam on Boat Performance

The beam of a boat plays a significant role in its performance, handling, and stability. Here are some of the ways boat beam affects performance:

The beam of a boat can affect its speed-to-length ratio. A narrower beam generally results in a higher speed-to-length ratio, which can increase the boat’s speed. On the other hand, a wider beam can decrease the speed-to-length ratio, which can reduce the boat’s speed.

Boat beam also affects the handling characteristics of a boat. A narrower beam generally allows for sharper turns and quicker response times, while a wider beam provides greater lateral stability. This means that boats with wider beams tend to be more stable, but they may not be as maneuverable as boats with narrower beams.

Performance

The beam of a boat can also impact its overall performance in terms of efficiency and maneuverability. A narrower beam generally results in a more efficient boat, as it creates less drag in the water. However, a wider beam can provide more space for passengers and cargo, which can increase the boat’s versatility.

The stability of a boat is also influenced by its beam. Boats with wider beams tend to be more stable , as they have a larger surface area in contact with the water. This can be especially important in rough water conditions, where a narrower boat may be more prone to tipping or capsizing.

In summary, the beam of a boat has a significant impact on its performance, handling, and stability. Boat owners should consider the intended use of their boat when selecting a beam size, as different beam widths can provide different benefits.

Different Types of Beams

Boats’ beams can vary in width and shape depending on the type of vessel. Here are some of the different types of beams:

Wider Beams

Boats with wider beams tend to be more stable in rough waters. This is because the wider beam acts as a strong foundation, reducing the rocking motion that can be experienced in narrower boats. Catamarans are a good example of boats with wider beams.

Narrow Beams

Boats with narrow beams tend to be faster and more maneuverable. This is because the narrower beam reduces the amount of drag that the boat experiences in the water. However, narrow beams can make boats less stable in rough waters.

Beam Overall

Beam overall refers to the width of a boat at its widest point. This is the most common way to measure a boat’s beam. It is important to note that the beam overall can vary depending on the type of boat.

Port Beam and Starboard Beam

Port beam and starboard beam refer to the width of a boat on its left and right sides, respectively. These measurements are important for ensuring that a boat is balanced and properly loaded.

As mentioned earlier, wider beams can provide more stability in rough waters. However, wider beams can also make boats less maneuverable and slower. It is important to find the right balance between stability and speed when choosing a boat.

In summary, the width and shape of a boat’s beam can have a significant impact on its performance and stability. Boats with wider beams tend to be more stable but less maneuverable, while boats with narrower beams tend to be faster but less stable. It is important to choose a boat with a beam that is appropriate for the intended use and conditions.

Beam in Different Types of Boats

The beam measurement of a boat can vary depending on the type of vessel. For instance, catamarans and trimarans have a wider beam compared to monohulls. Barges, on the other hand, have a beam that is significantly wider than other types of boats.

The beam is usually measured at the widest point of a boat’s hull, which is perpendicular to the waterline. In sailboats, the beam is measured at the deck level. The length overall (LOA) is also an important factor that affects the beam measurement of a boat. The longer the LOA, the wider the beam.

Multihull vessels, such as catamarans and trimarans, have two or more hulls that are connected by a deck. These types of boats have a wider beam than monohulls, which only have one hull. The beam measurement of a multihull vessel is usually taken at the waterline, which is the point where the hulls meet.

In contrast, monohulls have a narrower beam compared to multihulls. The beam measurement of a monohull is usually taken at the widest point of the hull, which is perpendicular to the waterline.

Overall, the beam measurement is an important factor that affects the stability and handling of a boat. A wider beam provides more stability, while a narrower beam allows for greater speed and maneuverability. Therefore, it is important to consider the beam measurement when choosing a boat for a specific purpose.

Role of Beam in Boat Construction

The beam is an essential component of any boat’s construction. It refers to the width of the vessel at its widest point, which is usually measured between the hull’s gunwales or the port and starboard sides. The beam plays a crucial role in the overall design and performance of a boat.

Material and Construction

The beam can be made from a variety of materials, including timber, fiberglass, aluminum, and steel. The choice of material depends on the boat’s intended use, size, and budget.

In terms of construction, the beam is typically integrated into the boat’s hull. It can be attached to the keel and chine , which are other critical components of a boat’s construction.

Abeam and Torsion Boxes

The beam is also responsible for the boat’s stability and carrying capacity. A wider beam can offer increased stability, which is especially important for larger vessels that carry more passengers and cargo. Additionally, a wider beam can provide more space for the boat’s occupants, resulting in overall comfort.

One important concept related to the beam is “abeam,” which refers to the position of the boat when the beam is perpendicular to the waves. This position can affect the boat’s stability and handling characteristics, depending on the size and shape of the hull.

Another important consideration is the use of torsion boxes, which are reinforced areas around the beam that help distribute the load and prevent twisting. Torsion boxes can improve the boat’s overall strength and durability, especially in rough waters.

Overall, the beam is a critical component of boat construction that affects the vessel’s performance, stability, and comfort. Boat builders must carefully consider the beam’s size, material, and construction to ensure that the boat meets the intended use and performs optimally in various conditions.

Beam in Nautical Navigation

The beam of a boat is an important measurement in nautical navigation. It refers to the width of the boat at its widest point, which is typically measured between the port and starboard sides of the hull. The beam is an essential factor in determining the stability and maneuverability of a vessel.

In nautical navigation, the beam is used to calculate the clearance required for a boat to pass through narrow channels or under bridges. It is also used to determine the maximum size of a vessel that can safely navigate a particular waterway. The beam of a boat is typically expressed in feet or meters.

When a boat is underway, the beam plays an important role in maintaining its stability. A wider beam provides more initial stability, but it can also reduce secondary stability in the event of a capsize. The deck beams of a ship are nearly vertical when it heels on its beam ends.

The beam of a boat can also affect its maneuverability. A wider beam can make a boat more difficult to turn, while a narrower beam can make it more agile. The beam is one of several factors that must be considered when selecting a boat for a particular purpose.

In summary, the beam of a boat is an important measurement in nautical navigation. It is used to determine the clearance required for a boat to pass through narrow channels, the maximum size of a vessel that can safely navigate a particular waterway, and the stability and maneuverability of a vessel. A wider beam provides more initial stability, but it can also reduce secondary stability in the event of a capsize. The beam is one of several factors that must be considered when selecting a boat for a particular purpose.

Considerations in Beam Design

When designing a boat, the beam is a critical measurement that impacts the vessel’s stability, handling, and overall performance. Here are some key considerations that naval architects and designers take into account when determining the appropriate beam for a boat.

Length-to-Beam Ratio

One important factor to consider is the length-to-beam ratio, which is the ratio of the boat’s length to its beam. This ratio can affect the boat’s speed, stability, and maneuverability. A boat with a high length-to-beam ratio will typically be faster but less stable, while a boat with a lower ratio will be more stable but slower.

Another factor to consider is the cube root of the boat’s volume, which is a measure of the boat’s overall size. The cube root can help designers determine the appropriate beam for a vessel based on its size and intended use.

Vessel Design

The design of the vessel also plays a role in determining the appropriate beam. For example, a boat with a center console may require a wider beam to accommodate the console and provide adequate space for passengers and gear.

Limitations

There are limitations to how wide a boat’s beam can be based on factors such as transportation restrictions and dock space availability. Designers must ensure that the boat’s beam is within these limitations while still meeting the vessel’s performance requirements.

Personal Preference

Personal preference also plays a role in determining the appropriate beam for a boat. Some boaters may prefer a wider beam for increased stability and comfort, while others may prefer a narrower beam for better speed and maneuverability.

Finally, designers must consider any obstacles that the boat may encounter, such as low bridges or narrow waterways. The beam must be narrow enough to navigate these obstacles safely.

In summary, the beam of a boat is a critical measurement that impacts the vessel’s stability, handling, and overall performance. Designers must take into account factors such as the length-to-beam ratio, cube root, vessel design, limitations, personal preference, and obstacles when determining the appropriate beam for a boat.

Frequently Asked Questions

What is the difference between beam and breadth of a ship.

The terms beam and breadth are often used interchangeably to refer to the width of a ship. However, technically speaking, beam refers to the maximum width of a ship at its widest point, while breadth is the measurement taken at the widest point of a ship’s hull.

How do you measure the beam of a boat?

To measure the beam of a boat, you need to measure the distance between the widest points on either side of the boat. This can be done using a tape measure or a specialized tool called a beam compass.

What is the beam on a boat called?

The beam on a boat is simply referred to as the beam. However, in nautical terms, it is sometimes referred to as the “beam overall” or BOA.

What are the 4 sides of a ship called?

The four sides of a ship are called the port side (left), starboard side (right), bow (front), and stern (back).

What is the height of a boat called?

The height of a boat is called its freeboard. This refers to the distance between the waterline and the uppermost point on the boat’s deck.

What is the front of a boat called?

The front of a boat is called the bow.

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About the author

I worked as an officer in the deck department on various types of vessels, including oil and chemical tankers, LPG carriers, and even reefer and TSHD in the early years. Currently employed as Marine Surveyor carrying cargo, draft, bunker, and warranty survey.

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Definitions

Length overall (LOA)

Length of water line (lwl)

Length between perpendiculars (LFF)

Rated length

he hull of a yacht is a complex three-dimensional shape, which cannot be defined by any simple mathematical expression. Gross features of the hull can be described by dimensional quantities such as length, beam and draft, or non-dimensional ones like prismatic coefficient or slenderness (length/displacement) ratio. For an accurate definition of the hull the traditional lines drawing; is still a common tool, although most professional yacht designers now take advantage of the rapid developments in CAD introduced in Chapter 1.

In this chapter we start by defining a number of quantities, frequently referred to in yachting literature, describing the general features of the yacht. Thereafter, we will explain the principles of the traditional drawing and the tools required to produce it. We recommend a certain work plan for the accurate production of the drawings and, finally, we show briefly how the hull lines are generated in a modern CAD program.

The list of definitions below includes the basic geometrical quantities used in defining a yacht hull. Many more quantities are used in general ship hydrodynamics, but they arc not usually referred to in the yachting field. A complete list may be found in the International Towing Tank Conference (ITTC) Dictionary of Ship Hydrodynamics.

The maximum length of the hull from the forwardmost point on the stem to the extreme after end (see Fig 3.1). According to common practice, spars or fittings, like bowsprits, pulpits etc are not included and neither is the rudder.

The length of the designed waterline (often referred to as the DWL).

This length is not much used in yachting but is quite important for ships. The forward perpendicular (FP) is the forward end of the designed waterline, while the aft perpendicular (AP) is the centre of the rudder stock.

The single most important parameter in any rating rule. Usually L is obtained by considering the fullness of the bow and stern sections in a more or less complex way.

The maximum beam of the hull excluding fittings, like rubbing strakes.

Fig 3.1 Definitions of the main dimensions

Beam of waterline (bwl)

Displacement

The maximum beam at the designed waterline.

The maximum draft of the yacht when floating on the designed waterline. Tc is the draft of the hull without the keel (the 'canoe' body).

The vertical distance from the deepest point of the keel to the sheer line (see below). Dc is without the keel.

Could be either mass displacement (m) ie the mass of the yacht, or volume displacement (V or V), the volume of the immersed part of the yacht. mc, Vc and Vc are the corresponding notations without the keel.

Midship section For ships, this section is located midway between the fore and aft perpendiculars. For yachts it is more common to put it midway between the fore and aft ends of the waterline. The area of the midship section (submerged part) is denoted AM, with an index 'c' indicating that the keel is not included.

Maximum area section For yachts the maximum area section is usually located behind the midship section. Its area is denoted Ax (AXc).

Prismatic coefficient This is the ratio of the volume displacement and the maximum section (CP) area multiplied by the waterline length, ie CP = V/(AX • Lwl). This value is very much influenced by the keel and in most yacht applications only the canoe body is considered: CPc = Vc(AXc • Lwl). See Fig 3.2. The prismatic coefficient is representative of the fullness of the yacht. The

Circumscribed cylinder volume = v = L^ Ay

Fig 3.2 The prismatic coefficient

BOX WL WL c

Circumscribed box volume =

Fig 3.3 The block coefficient

Block coefficient ( CB)

Centre of buoyancy (B)

Centre of gravity (G)

Freeboard fuller the ends, the larger the Cp. Its optimum value depends on the speed, as explained in Chapter 5.

Although quite important in general ship hydrodynamics this coefficient is not so commonly used in yacht design . The volume displacement is now divided by the volume of a circumscribed block (only the canoe body value is of any relevance) CBc = V J(Lwl • BWL • Tc). See Fig 3.3.

The centre of gravity of the displaced volume of water, its longitudinal and vertical positions are denoted by LCB and VCB respectively.

The centre of gravity of the yacht must be on the same vertical line as the centre of buoyancy. In drawings G is often marked with a special symbol created by a circle and a cross. This is used also for marking geometric centres of gravity. See. for instance, Figs 5.27 or 8.2.

The intersection between the deck and the topside. Traditionally, the projection of this line on the symmetry plane is concave, the 'sheer* is positive. Zero and negative sheer may be found on some extreme racing yachts and powerboats.

The vertical distance between the sheer line and the waterline.

Tumble home

When the maximum beam is below the sheer line the upper part of the topsides will bend inwards (see Fig 3.4). To some extent this reduces the weight at deck level, but it also reduces the righting moment of the

Fig 3.4 Definition of tumble home and flare

Tumble home crew on the windward rail. Further, the hull becomes more vulnerable to outer skin damage in harbours.

Flare The opposite of tumble home. On the forebody in particular, the sections may bend outwards to reduce excessive pitching of the yacht and to keep it more dry when beating to windward.

Scale factor (a) This is not a geometrical parameter of the hull, but it is very important when designing a yacht. The scale factor is simply the ratio of a length (for instance the Lw,) at full scale to the corresponding length at model scale. Note that the ratio of corresponding areas (like the wetted area) is a2 and of corresponding volumes (like displacement) a3.

Lines drawing A complete lines drawing of the YD 40 is presented in Fig 3.5. The hull is shown in three views: the profile plan (top left), the body plan (top right) and half breadth plan (bottom). Note that the bow is to the right.

In principle, the hull can be defined by its intersection with two different families of planes, and these are usually taken as horizontal ones (waterlines) and vertical ones at right angles to the longitudinal axis of the hull (sections). While the number of waterlines is chosen rather arbitrarily, there are standard rules for the positioning of the sections. In yacht architecture the designed waterline is usually divided into ten equal parts and the corresponding sections are numbered from the forward perpendicular (section 0) backwards. At the ends, other equidistant sections, like # 11 and # 1 may be added, and to define rapid changes in the geometry, half or quarter sections may be introduced as well. In Fig 3.5 half sections are used throughout.

The profile is very important for the appearance of the yacht, showing the shapes of the bow and stern and the sheer line. When drawing the waterlines, displayed in the half breadth plan, it is most helpful if the lines end in a geometrically well defined way. Therefore a 'ghost" stem and a 'ghost' transom may be added. The ghost stem is the imagined sharp leading edge of the hull, which in practice often has a rounded stem, and the ghost transom is introduced because the real transom is often curved and inclined. If an imagined vertical transom is put near the real one at some convenient station, it will facilitate the fairing of the lines. The drawing of Fig 3.5 has been produced on a CAD system and no ghost stem is shown. However, a ghost transom is included.

In the body plan, the cross sections of the hull are displayed. Since the hull is usually symmetrical port and starboard, only one half needs to be shown, and this makes it possible to present the forebody to the right and the afterbody to the left. In this way mixing of the lines is avoided and the picture is clearer. Note that in the figure the half stations are drawn using thinner lines.

The above cuts through the hull are sufficient for defining the shape, but another two families of cuts are usually added, to aid in the visual perception of the body. Buttocks are introduced in the profile plan,

* * ^ "i * 2 § 2 II II II II II II II ll II

showing vertical, longitudinal cuts through the hull at positions indicated in the half breadth plan. The diagonals in the lower part of the half breadth plan are also quite important. They are obtained by cutting the hull longitudinally in different inclined planes, as indicated in the body plan. The planes should be as much as possible at right angles to the surface of the hull, thus representing its longitudinal smoothness. In practice, the flow tends to follow the diagonals, at least approximately, so that they are representative of the hull shape as "seen' by the water. Special attention should be paid to the after end of the diagonals, where knuckles, not noticcd in the other cuts, may be found, particularly on lOR yachts from the 1970s and the 1980s. Almost certainly, such unevenncss increases the resistance and reduces the speed of the yacht.

The other line in the lower part of the half breadth plan is the curve of sectional areas, representing the longitudinal distribution of the submerged volume of the yacht. The value at each section is proportional to the submerged area of that section, while the total area under the curve represents the displacement (volume). A more detailed description of the construction of the curve of sectional areas will be given in Chapter 4.

In order to define exactly the shape of the hull a table of offsets is usually provided by the designer. This is to enable the builder to lay out the lines at full size and produce his templates. Offsets are always provided for the waterlines, but the same information may be given for diagonals and/or buttocks also. Note that all measurements are to the outside of the shell.

The drawing should be made on a special plastic film, available in different thicknesses. The film is robust and will not be damaged by

Photo 3.6 Tools (triangle, plastic film, straight edge, brush, pens, pencil, erasing shield and eraser)

Photo 3.7 Tr¿\nster of measures from body plan (top) to half breadth plan (bottom) using a paper ribbon

erasing. Furthermore, it is unaffected by the humidity of the air. which may shrink ordinary paper.

Since the film is transparent the grid for the lines drawing is drawn on the back so that it will remain, even after erasing the hull lines on the front many times. Great care must be exercised when drawing the grid, making sure that the alignment and spacing are correct and that all angles arc cxactly 90°. In Fig 3.5 the grid is shown as thin horizontal and vertical lines, representing waterlines, buttocks and stations.

Black ink should be used when drawing the grid and preferably when finishing the hull lines also. However, when working on the lines a pencil and an eraser are needed. There are, in fact, special pencils and erasers for this type of work on plastic film. An erasing shield and a brush are also most useful (see Photo 3.6).

For creating the grid a long straight edge is required, together with a

Photo 3.8 Ducks and a spline used for drawing a water Iine

Photo 3.9 Templates used for drawing lines with large curvature

large 90° set square. It is very convenient to have a bunch of paper ribbons, which can be used for transferring different measures from one plan to the other. For example, when drawing a waterline the offsets of this line may be marked on the ribbon directly from the body plan and moved to the half breadth plan (Photo 3.7).

To draw the hull lines it is necessary to have a set of splines and weights or ducks. Long, smooth arcs can be created when bending the splines and supporting them by the ducks at certain intervals. Photo 3.8 shows how these tools are used when drawing a waterline. The splines should be made of plastic, somewhat longer than the hull on the drawing, and with a cross-section of about 2.5 mm2. Many different types of ducks can be found, some of them home made. Preferably,

Photo 3.10 PI an i meter they should be made of lead, and the weight should be between 1.5 and 2.5 kg. To be able to support the spline, they should have a pointed nose, as shown in Photo 3.8.

The splines are needed when drawing the lines in the profile and half breadth plans. However, the lines of the body plan are usually too curved for the splines, so it is necessary to make use of a set of templates especially developed for this purpose. The most well known ones are the so called Copenhagen ship curves, the most frequently used of which are shown in Photo 3.9.

A very convenient instrument, well known in naval architecture, is the planimeter, used for measuring areas (see Photo 3.10). The pointer of the planimeter is moved around the area to be measured, and the change in the reading of the scale when returning to the point of departure gives the area enclosed by the path followed. Considering the difficulty in following exactly any given line the accuracy is surprisingly high, more than adequate for the present purposes. The need for measuring areas will be explained in the next chapter.

Since many calculations have to be carried out when preparing the drawings, and indeed in the whole design process, an electronic calculator is essential. A simple one would be sufficient in most cases, but a programmable calculator would simplify some of the calculations, particularly if a planimeter is not available. Most scientific calculators have programs for calculating areas with acceptable accuracy, and programs are available for most of the calculations described in the next chapter.

Designing the hull is a complex process, and many requirements have to be considered. One difficulty is that important parameters, such as the displacement cannot be determined until the lines have been fixed. This calls for an iterative method. Such a method is also required in the fairing of the lines. The problem is to make the lines in one projection correspond to smooth lines in the other two projections. For an inexperienced draftsman this problem is a serious one, and many trials may be needed to produce a smooth hull.

While the preferred sequence of operations may differ slightly between yacht designers the main steps should be taken in a certain order. In the following, we propose a work plan, which has been found effective in many cases. It should be pointed out that the plan does not take into account any restrictions from measurement rules.

Step 1: Fix the main dimensions These should be based on the general considerations discussed in Chapter 2, using information on other yachts of a similar size, designed for similar purposes. This way of working is classical in naval architecture, where the development proceeds relatively slowly by evolution of previous designs. It is therefore very important, after deciding on the size of the yacht, to find as much information as possible on other similar designs. Drawings of new yachts may be found in many of the leading yachting magazines from all over the world.

The dimensions to fix at this stage are: length overall, length of the waterline, maximum beam, draft, displacement, sail area, ballast ratio, prismatic, coefficient and longitudinal centre of buoyancy. One of the aims of this book is to help in the choice of these parameters and to enable the reader to evaluate older designs when trying to find the optimum for his own special demands.

Step 2: Draw the profile As pointed out above, this step takes much consideration, since the aesthetics of the yacht are, to a large extent, determined by tBfe pi^ffle-

Step 3: Draw the midship section The midship section can be drawn at this stage, or, alternatively, the maximum section if it is supposed to be much different. This may occur if the centre of buoyancy is far aft. The shape of the first section drawn is important, since it determines the character of the other sections.

Step 4: Check the displacement To find the hull displacement calculate (or measure) the submerged area of the section just drawn and multiply by the waterline length and the prismatic coefficient chosen for the hull. From the ballast ratio, the keel mass can be computed and the volume can be found, dividing by the density of the material (about 7200 kg/m3 for iron and 11300 kg/m- for lead). Assume that the rudder displacement is 10% of that of the keel and add all three volumes. If the displacement thus obtained is different from the prescribed one, return to step 3 and change accordingly.

The procedure described is for a fin-keel yacht. For a hull with an integrated keel, as on more traditional yachts, the prismatic coefficient usually includes both the keel and the rudder.

Step 5: Draw the designed waterline One point at or near the midship station is now known, together with the two end points from the profile, so now a first attempt can be made to draw the designed waterline.

Step 6: Draw stations 3, 7 and the transom The waterline breadth is now known, as well as the hull draft, and the sections should have a family

resemblance to the midship section. Often it is helpful to draw a ghost transom behind the hull.

Step 7: Draw new waterlines Two or three waterlines can now be drawn above and below the DWL. If the appearance is not satisfactory, go back to step 6 and change.

Steps 8 and 9: Add new sections and waterlines

Once this is done, sections I-9 should be completed as well as 7-10 waterlines. Constant adjustments, have to be made in order to create smooth lines in the body plan, as well as in the half breadth plan.

Step 10: Recheck the displacement and the longitudinal centre of buoyancy The curve of sec tional areas can now be constructed. Its area gives the displacement (excluding that of keel and rudder) and its centre of gravity corresponds to the longitudinal position of the centre of buoyancy. If not correct, adjustments have to be made from steps 5 or 6,

Step 11: Draw diagonals Inspect the smoothness, particularly near the stern. Adjust if necessary.

Step 12: Draw buttocks This is the final check on the smoothness. Usually only very minor corrections have to be made at this stage.

Computer aided design of hulls

As mentioned in Chapter 1, most CAD programs use master curves for generating the hull surface. Each curve is defined by a number of points, called vertices. Photo 3.11 shows, in a plan view, the grid of master curves used for generating the YD-40 hull. One of the transverse curves has been selected in Photo 3.12 and it can be seen how the smooth hull surface is generated inside the curve, which is shown as piece-wise linear between the vertices.

Photo 3.11 Grid of master curves used for the YD-40 (the vertical line to the right marks the origin of the coordinate system)

Photo 3.12 A section with vertices (crosses), master curve (between the crosses), hull surface and cuwature (outermost line)

The task of the designer is to specify the vertices in such a way that the desired hull shape is created.There are different ways of achieving this. Some programs start from a long cylindrical body or a box, while others start from a flat rectangular patch, defined by an orthogonal grid. These original shapes are then distorted by moving the vertices around, and it is relatively easy to produce a yacht-like body. However, it takes experience and experimentation to obtain a shape that satisfies criteria set up beforehand. In practice, designers very seldom start from scratch, but work from earlier designs, which already have a desirable shape and a known grid of master curves surrounding it. Since most new designs are evolutions of previous ones this approach is very natural.

A problem encountered when the first CAD programs for yachts appeared was that the scale on the screen was too small, and the resolution too low to enable the designer to create fair lines. Small bumps on the surface could not be detected 011 the screen, and it sometimes happened that the bumps were noticed only after the start of the hull construction . Therefore the CAD program developers introduced plots of the curvature of lines on the hull. Such a plot is shown.in Photo 3.12. The curvature of the line, which essentially corresponds to a section, is almost constant, except at the ends where it goes to zero.

Photo 3.13 illustrates the sensitivity of the curvature to small changes of the surface. The sheer line is shown in a plan view. In the top photo (the real design) the curvature is smooth and relatively constant along the hull. In the bottom photo one vertex point has been moved 10 mm at full scale perpendicular to the surface. The resulting change in the sheer line is so small that it cannot be detected by eye, but the curvature exhibits a considerable bump and some smaller fluctuations, showing that the line is not smooth. By looking at the curvature, lines may thus be generated that look fair even at full scale.

Photo 3.13 Sheer line with vertices and curvature. (top) Real design. (bottom) One vertex point moved 10 mm

Photo 3,14 Perspective view A great advantage of most CAD programs is that the hull may be of the YD-40 shown in perspective. As pointed out in Chapter 1 it is important to study the sheer line in particular from different angles, since the impression of the hull contour in reality is also influenced by the beam distribution, which is not visible if only the profile view is studied. Fig 3.14 shows the YD-40 in perspective, and a good impression can be obtained of the shape. "

By using a CAD program a fair hull can be produced rapidly and different requirements may be satisfied without too much work, such as a given prismatic coefficient or longitudinal centre of buoyancy. Meeting such requirements accurately in a manual process is extremely time consuming, so it is understandable that CAD techniques are always used nowadays by professional designers. However, due to the considerable cost of a CAD system, most amateur designers will still have to use the manual approach described above.

Continue reading here: Hydrostatics And Stability

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Readers' Questions

What do you understand by drawing defines the shapes of the hull.?

How to figure the width to height to length of a yacht?

To figure out the width, height, and length of a yacht, you typically need to refer to the yacht's specifications provided by the manufacturer, yacht designer, or owner. These specifications should include the appropriate measurements. Consult the yacht's specifications: Look for the official documentation or technical information provided for the yacht. This documentation usually includes the length, width, and height of the yacht, referred to as LOA (Length Overall), Beam, and Draft, respectively. The specifications are usually available in brochures, user manuals, or on the official website of the yacht manufacturer. Seek professional advice: If you cannot find the specifications yourself or need more specific information, consider reaching out to yacht brokers, yacht builders, naval architects, or other professionals in the yachting industry. They have extensive knowledge and can guide you with accurate measurements or provide information by using the yacht's model or brand. Measure the yacht yourself: If you have physical access to the yacht and cannot find the specifications through other means, you can measure it directly. However, this method is less accurate and should only be used as a last resort. Use a measuring tape or other appropriate tools to measure the overall length, width or beam, and height. Ensure to measure from fixed reference points for consistency and accuracy. Remember that yachts come in various sizes, designs, and layouts. The width or beam, for example, may be different at different points along the vessel's length due to design variations. It is essential to refer to the official specifications or seek professional advice for the most precise and reliable measurements.

Can you use geometry on boats?

Yes, geometry can be applied to various aspects of boats, particularly in the design and construction phase. Here are a few examples: Hull Design: Geometry is crucial in designing the shape and dimensions of a boat's hull. The angles, curves, and mathematical calculations are used to ensure stability, hydrodynamics, and buoyancy. Stability Analysis: Geometry is used to determine the center of buoyancy, center of gravity, and metacenter of a vessel. These calculations are essential for assessing a boat's stability, both at rest and in motion. Navigation and Bearings: Geometric concepts such as angles, triangles, and trigonometry are used to calculate headings, course corrections, and bearings while navigating a boat. Sail Measurement and Adjustments: Sailboats utilize various geometric principles to determine sail sizes, aspect ratios, and shapes. The geometry of sail adjustments, such as tightening or loosening the sail, can affect the boat's speed and performance. Nautical Charts: Geometry plays a vital role in nautical charting, which involves representing the Earth's curved surface on a flat chart. Projections, grid systems, and coordinate systems are employed to accurately depict and navigate waterways. These are just a few examples of how geometry can be applied to boats. Overall, geometry is critical in ensuring boat design, navigation, and performance, making it an important aspect of the boating industry.

How to find ship displacement from submerged area?

To find the ship displacement from submerged area, you can follow these steps: Determine the underwater or submerged area of the ship. This can be done by calculating the area of the ship's hull that is below the waterline when it is fully submerged. Convert the area into a volume by multiplying it by the ship's beam (width) or mean draft (depth). Multiply the volume by the density of the water. The density of water varies slightly depending on temperature and salinity, but a typical value is around 1,000 kilograms per cubic meter. The result of this calculation will be the ship's displacement. It represents the weight of the water displaced by the ship when it is fully submerged. Note: This method assumes that the ship's hull has a constant shape below the waterline. In reality, the shape may vary, especially towards the ends of the ship.

How to draw a simple ship?

To draw a simple ship, follow these step-by-step instructions: Start by drawing a horizontal line slightly curved at the ends to create the ship's hull. Add a smaller curved line above the hull to outline the ship's deck. At the front of the ship, draw a triangular shape for the bow. On top of the deck, draw a small rectangular structure or cabin. Add a flagpole at the back of the deck by drawing a long, thin rectangle. Draw a small rectangle or square at the top of the flagpole for the flag. Next, add a slightly curved line near the waterline for the keel of the ship. On both sides of the hull, draw a series of diagonal lines to create the ship's planking. To indicate windows or portholes, draw small oval or circular shapes along the cabin. Add a couple of mast poles on the deck. To do this, draw two vertical lines with a horizontal line connecting them at the top. On top of the mast poles, add triangular or rectangular shapes for the sails. Finally, erase any unnecessary guidelines, and you can add more details like waves or seagulls to complete your simple ship drawing. Remember, this is just one way to draw a simple ship. Feel free to modify the design or add additional elements to make it your own!

How to draw a pin keeldrawing tutorialtop keel?

To draw a pin keel, follow these steps: Begin by drawing a slightly curved horizontal line. This line will serve as the water surface. Next, draw a long vertical line that will represent the keel. The keel should start at the bottom of the water surface line and extend downward. At the bottom of the vertical line, draw a slightly curved horizontal line. This line will represent the lower part of the keel. On the left side of the keel, draw a diagonal line extending outward. This line will represent the forward part of the keel. Repeat the previous step on the right side of the keel, drawing a diagonal line to represent the aft part. Connect the ends of the diagonal lines with a curved line, forming the bottom part of the keel. Add additional detail to the keel by drawing a small horizontal line near the top. This line represents the top part of the keel. Finally, erase any unnecessary lines and add shading to give the keel more depth and dimension. Remember to take your time and practice as much as needed to improve your drawing skills.

How do you draw a ship?

Drawing a ship can be a fun and creative process. Here's a step-by-step guide on how to draw a ship: Start by drawing a long, slightly curved horizontal line in the center of your paper. This line will serve as the ship's waterline. From one end of the waterline, draw a slanted rectangle shape, slightly wider at the bottom than the top. This will be the ship's hull. At the other end of the waterline, draw a smaller rectangle shape, slightly tilted upward. This will be the ship's bow. Connect the bow and the hull with two diagonal lines, creating the ship's front structure. Add a large, slightly curved rectangle shape at the top of the hull. This will be the main deck of the ship. Draw a smaller rectangle shape above the main deck to represent the ship's superstructure. Sketch two parallel, slanted lines on the front of the ship's superstructure to create the pilot house. On the main deck, draw a few rectangular shapes to indicate windows or portholes. Add details like railing, stairs, and lifeboats on the sides and top of the ship as desired. Extend the hull below the waterline using a curved line to give the ship depth. For the finishing touches, you can draw some waves around the ship, seagulls in the sky, or a flag on top. Remember to be creative and modify the design as you like. Don't worry if your drawing doesn't turn out perfect at first; practice makes perfect!

What hull curves do yachts fallow is it x squared?

The hull curves of yachts can vary depending on the design and purpose of the yacht. While some yacht hulls may follow a curve that resembles the function of x squared, others may follow different curves such as parabolic curves, ellipses, catenary curves, or other mathematical shapes. The specific curvature of a yacht's hull is determined by factors such as the desired speed, stability, maneuverability, and hydrodynamic efficiency of the vessel. It is typically designed by naval architects and engineers who consider various factors including the size and weight distribution of the yacht, the intended use (e.g., racing, cruising, etc.), and materials used in construction. In summary, while some yachts may have hull curves similar to x squared, there is no universal standard hull curve for all yachts. The hull design depends on various factors and can incorporate different mathematical curves to achieve specific performance characteristics.

How to calculate the curvature of a boat?

To calculate the curvature of a boat, you would need to determine the radius of its curvature. The curvature refers to the degree of how much the boat's hull curves or bends. Gather the measurements: You will need the length and width measurements of the boat. These measurements can be obtained from the boat's specifications or by physically measuring it. Determine the midpoint: Locate the midpoint of the boat's length. This can be done by dividing the boat's length measurement by 2. Measure the rise: Starting from the midpoint, measure the distance between the bottom of the boat's hull and a straight line connecting the bow and stern (i.e., the rise). Measure the run: Measure the distance between the midpoint and the bottom of the boat's hull at the bow and stern. Calculate the radius of curvature: The radius of curvature can be calculated using the following formula: Radius = (run^2 + rise^2) / (8 x rise). The curvature: The curvature is calculated as the reciprocal of the radius of curvature. It's important to note that this calculation assumes a boat's hull shape can be represented by a simple section of a circle. More complex hull shapes, such as those with multiple curves or irregular shapes, may require different mathematical models or numerical methods to accurately determine curvature.

How to measure the curveture of a boat hull?

There are several methods to measure the curvature of a boat hull. Here are three common techniques: Profiling: This method involves taking measurements at specific points along the hull's surface to understand the curvature. You can use a flexible measuring tape or string to measure the distance from the hull to a straight reference line at different points along the boat's length. These measurements can then be plotted on a graph to depict the curvature of the hull. Reflection Method: For this technique, you need a laser level and a measuring tape. Firstly, position the laser level at a fixed distance from the boat hull and horizontally direct the laser beam towards the hull. The laser beam will be reflected back from the hull surface. Measure the distance from the laser level to the hull at different points along the boat's surface. These measurements can be used to calculate the curvature of the hull. 3D Scanning: Utilizing modern technology, you can use a 3D scanner to create a digital model of the boat hull. The scanner emits laser beams or projects structured light patterns onto the hull, capturing its shape in detail. The resulting 3D model can then be used to measure the curvature of the hull accurately. It is important to note that measuring the curvature of a boat hull may require specific tools and expertise. Hence, it is advised to consult with industry professionals or specialists for accurate measurements.

How to draw a yacht keel?

To draw a yacht keel, you can follow these steps: Start by drawing a horizontal line on your paper. This line will serve as the waterline. From the center point of the waterline, draw two vertical lines going downward to create the main part of the keel. These lines should taper towards the bottom. At the bottom of the keel, draw a horizontal line connecting the two vertical lines. This will form the bottom edge of the keel. Now, draw a diagonal line on each side of the keel, starting from the top and curving slightly outward. These lines will form the shape of the keel as it narrows towards the top. Connect the ends of the diagonal lines at the top with a smooth curve to create the rounded shape of the keel. Next, draw horizontal lines across the keel to represent the different sections or layers. These lines can be evenly spaced or closer together at the top and gradually getting wider towards the bottom. Add details such as ribbing or reinforcements by drawing diagonal lines across the keel, intersecting the horizontal lines. To give the keel a more realistic look, you can shade the bottom part and add some shadow where it meets the waterline. Finally, you can add additional details such as a bulbous bow or a fin at the bottom of the keel based on the specific design of the yacht you are drawing. Remember to sketch lightly at first and gradually darken your lines as you refine the shape. And don't forget to have fun and experiment with different styles and variations to make your drawing unique!

How to draw a boat into transverse stations?

Drawing a boat into transverse stations can be done by following these steps: Start by selecting a suitable scale for the drawing. This will depend on the size of the boat you want to draw and the size of the paper or canvas you are using. Begin by drawing a horizontal line across the paper, representing the waterline. Next, draw vertical lines representing the transverse stations at regular intervals along the waterline. These lines should be evenly spaced and represent the cross-sections of the boat at different points along its length. Use reference drawings or images of the boat to guide your drawing. Start by drawing the outline of the boat's hull within each station. Pay attention to the curvature and tapering of the hull as it moves towards the bow and stern. After drawing the outline, add any additional details such as deck lines, windows, hatches, and other features of the boat. Use shading techniques to add depth and dimension to the drawing. Pay attention to the light source and add shadows accordingly to create a realistic representation of the boat. Finally, go over your drawing and make any necessary adjustments or corrections to ensure accuracy.

What is nonprismatic hull?

A nonprismatic hull is a type of hull shape in naval architecture that does not conform to the standard prismatic shape of traditional sailing vessels. Nonprismatic hulls are designed to increase performance in certain areas such as speed and efficiency, as well as to reduce drag and enhance maneuverability. Nonprismatic hulls are also often used as part of a wave piercing design to cut through wave crests, thus reducing the size of the wake behind the ship.

How to design a schooner hull?

Research the history of schooner hulls and their design features. This will help you understand the shipbuilding principles and methods used in their construction. Consider the type of schooner you want to design. Is it a racing vessel or a cruising boat? This will help you determine the size, weight and other characteristics of the hull. Consider the type of material you will use for the schooner. Traditionally, schooner hulls have been made of wood or fiberglass, but there are other materials that can be used as well. You need to choose a material that meets your needs and budget. Work with an experienced maritime designer or drafter to create a 3D model of the schooner hull. This will help you visualize the hull and make sure it meets your specifications. Have a qualified shipwright or boat builder construct your schooner. Ensure that the schooner is tested and certified by a naval architect before you take it out on the water.

How to draw hull lines plan from boat existing images in reverse engineering?

Take a picture of the boat's existing lines plan. Import the image into a vector graphic program such as Inkscape, Adobe Illustrator, or Corel Draw. Trace the contours of the boat's hull using the Pen Tool or other trace tool in the program. Adjust the lines to make sure they accurately represent the boat's shape and contours. Once the lines plan is complete, use a ruler to draw perpendicular lines from the boat's existing lines plan as a reference for the hull. Use the curved line tool to refine the shape of the hull and make sure everything is in proportion and accurate. Double-check to make sure the hull lines plan is correct, and save the file for future reference.

What does half a sideways figure eight mean on a ship drawing?

Half a sideways figure eight on a ship drawing typically denotes the ship's waterline—the line where the ship sits in the water.

How to work out the shape and profile of a yatch datum line?

Establish the design criteria and parameters of the yacht. This should include the length, width, height and any other characteristics relevant to the design of the yacht. Define the design goals and objectives of the yacht, including the purpose and function of the yacht, how it will be used, and what type of sailing or other activities will take place on it. Choose an appropriate hull shape and size for the yacht based on the design criteria, goals and objectives. Create a 3D computer model of the yacht design, incorporating the appropriate hull shape and size. Use the model to define a datum line for the yacht, which will help to accurately measure the craft's performance and characteristics. The datum line should run from the center of the waterline around the hull to the transom. Using the 3D model, define the profile of the yacht by “lofting” the curves of the hull and the deck. Refine the design by adjusting the curves of the hull and deck to ensure that the yacht's performance characteristics are maximized. Use the computer model to run “virtual wind tunnel” tests on the design, to ensure that its performance characteristics are optimized.

How to draw a boat on water?

Start by sketching the basic shape of the boat. Start with a long, rectangular shape to form the hull of the boat. Add a slight curve to the top of the boat to give it an authentic boat shape. Draw a smaller rectangular shape for the cabin of the boat. Sketch two triangular shapes on the left and right side of the cabin for the sails. Draw a series of small circles along the bottom of the boat to create the waterline. Now add the details to your boat: windows, doors, life preservers, etc. Finally, draw some small waves around the boat to create the illusion of the boat sailing on water.

What are fair lines and sheer lines of a yacht?

Fair lines are the contours of the yacht's hull. Sheer lines are the long, gradual arch of the deck, starting at the bow and extending to the stern.

How to draw a hardshine boat hull quickly?

To draw a hardshine boat hull quickly, you can follow these steps: Start by drawing a horizontal line to represent the waterline. This line will serve as the base for the boat hull. Sketch a rough outline of the boat hull shape above the waterline. Keep in mind that hardshine boat hulls are typically streamlined and have a sharp, angular shape. Add a slightly curved line below the waterline to depict the bottom part of the hull. The curve should be gentle and gradually merge into the horizontal waterline. Extend two diagonal lines downward from the front end of the boat hull to create the bow. The bow should be pointed and sharp to cut through the water efficiently. Add a small transom at the rear end of the boat hull. The transom is usually flat or slightly curved upward. Sketch two straight lines from the bow to the stern to represent the deck of the boat. Draw a horizontal line across the middle section of the hull to indicate a separation or border between the upper and lower parts. Add details to the hull, such as chines (angled lines along the sides of the hull) and spray rails (small fins or ridges). These elements contribute to the boat's stability and improve its performance in the water. Shade the lower portion of the hull with a darker tone to emphasize the hardshine effect. Use quick and light strokes to achieve a glossy appearance. Finally, erase any unnecessary guidelines and refine the drawing as needed. Remember, practicing and experimenting with different techniques will help you improve your drawing skills and speed over time.

How to measure a ships hull shape from inside?

One way to measure a ship's hull shape from inside is by using 3D laser scanning. This technique uses lasers to take precise measurements of a ship's inner hull shape. The lasers scan around the interior of the ship and create a 3D image of the ship's shape. This data can then be used to create a precise and accurate measure of the ship's hull shape.

How to lay out a lines drawing for displacement hulls?

Start by drawing the waterline at the mid-point of the vessel. Draw the bow from the top of the waterline to the nose of the vessel. Draw the stern from the bottom of the waterline to the end of the vessel. Draw in all of the chines of the vessel, the curved lines along the bottom of the sides of the boat, at the waterline. Draw in any other details such as the upturned bow, the tail, or any other details that the vessel may have. Draw the sheer line and the sheer forward, running along the top of the vessel and curving inwards and downwards in the center. Add in any additional lines needed to complete the displacement hull. Use a protractor to make sure all of the angles are correct. Use a ruler to draw the exact lines and make sure the lines are the correct length.

My Cruiser Life Magazine

What is a Boat’s Beam? Your Guide to the Beam on a Boat

A boat’s beam is the widest point of the boat. It’s an important measurement to know, just like the length of your boat is vital to know. Like many things in boat design, the beam is one of the tools that yacht designers tinker with to get just the right characteristics. But it also has lots of implications for boat owners too, so let’s take a closer look at a boat’s beam.

Table of Contents

What is “beam” on a boat exactly, beam of the boat and boat performance, boat length and beam, beam and marina choices, beam and cabin size and space, beam and navigation, beam and stability, wide boat beams pros, wide beam boat cons, narrow beam boat pros, narrow beam boat cons, trailer boat beam, narrow beam boats, measuring a boat’s beam, finding the beam sweet spot, faqs (frequently asked questions).

The beam of a boat is the widest point of the boat. It is usually located at the middle or slightly aft of the middle of the boat.

A boat’s beam impacts its performance in several ways:

• Stability : Wider beamed boats are generally more stable than narrower boats. They are less likely to capsize in waves.
• Speed and maneuverability : Narrower beamed boats are often faster and more maneuverable than wider boats.
• Comfort in waves : Narrower boats tend to slice through waves better, while wider boats are more likely to feel the impact of waves and chop.
• Living space : A wider beam provides more interior cabin space and storage capacity compared to a narrower boat of the same length.
• Trailering : Boats with beams under 8’6″ wide can be trailered on the road in most U.S. states without special permits. Wider boats may require permits.

Traditional Beam Terminology

Traditionally, boatbuilders used large wooden beams to create the boat’s frame. These beams ran laterally across the boat. As a result, a ship under construction looked like a massive ribcage, with support beams laid out. Boatbuilders would then add the rest of the wooden structure around the beam skeleton. 

The center beam was usually the longest and thickest beam. This beam’s measurement was used to measure the width of the boat. Today, the word “beam” still refers to the boat’s widest point…although sometimes it’s not in the center and it’s seldom made of wood.

Smaller boats under 20 feet often have a two-to-one ratio. Your eight-foot dinghy will probably have a beam of about four feet. Boats over 30 feet have a bigger ratio, often about three-to-one, four-to-one, or five-to-one. A sailing monohull might be 40 feet long and 12 feet wide.

These are just estimates and rules of thumb, of course. A boat’s beam is one of those things carefully considered by yacht designers and manufacturers. They want just the right handling characteristics, speed, and stability.

Beam Impacts on a Boat

Today, when someone asks about your boat’s beam, they want to know how wide your boat is. Your boat’s beam can impact your navigation possibilities, your marina choices, the size and comfort of your living space, and your comfort at sea.

Your boat’s beam can affect your marina options. Many marinas were built decades ago when narrower beamed boats were standard. Today’s more modern boats often have wider beams to provide a roomier feel in the cabin and give boaters more space. Older marinas might easily accommodate boats with a beam of 12 feet but may struggle to find a place for boats with larger beams.

If you have a large beamed boat such as a catamaran or trimaran, your marina choices will be even more limited. In addition, you might have a harder time finding a boatyard that can haul your boat and place it into dry storage. Many marina boat lifts are limited to hauling boats with beams less than 20 feet wide.

The larger the beam, the more space you’ll have in the boat’s cabin. If you are looking at liveaboard boats, you might be drawn to beamier boats with more space and storage options. Extra beam adds an enormous amount of space to the interior of the boat. This is one reason that trawlers and powerboats feel so much roomier than monohull sailboats–they have greater beams and they carry that beam all the way aft. 

In sailboats, it’s a modern design trend to make beamier boats. Plus, the beam is carried much farther aft than in traditional designs, resulting in wide-open cockpits and large, flat transoms.

The smaller your beam, the more places you can visit. In England, narrowboats have beams that are less than seven feet wide. These narrowboats can navigate England’s canal system. Some of England’s canal locks are very narrow, and only boats that can squeeze through seven-foot wide locks can successfully navigate these beautiful canals. 

There are many other examples of a boat’s beam affecting a boater’s navigation possibilities. For example, some French canals can only accommodate beams of up to 15 feet. To successfully complete America’s Great Loop, boaters should use a boat that is less than 23 feet wide.

Related: Best Boat for the Great Loop

Boats with narrower beams are often faster, especially if they have a longer waterline. However, they might be less stable than a wide-beamed boat.

Boat Design – Is More Beam Better?

In many ways, the beam of a boat is a matter of personal taste. Here’s a look at the pros and cons of wide boats vs narrowboats.

Wider boats are often more stable. For example, if you are looking for a stand-up fishing kayak, you’ll want a boat with a wider beam. A kayak with a narrow beam will be faster and more maneuverable but will be very hard to stand up on while keeping your balance.

Wider boats have more weight capacity than narrower boats of the same length. If you are hauling gear in your boat or need more room to spread out, a wider beamed boat might suit your needs better.

If you trailer your boat, a boat with a wide beam might be more challenging to tow on the road. In most states, if your boat is wider than 8’6″ you’ll need a special permit to tow your boat on the road. 

Many marinas are built with narrower boats in mind. Most marinas will find room for boats with beams less than 16 feet. Anything bigger, and you might struggle to find a traditional marina slip. 

In addition, a wide beamed boat might be too wide for older canal systems.

A narrow beamed boat is often more maneuverable and faster. Have you ever seen an Olympic sculling race? These narrow, long boats can really fly! If you are looking for a fast, fun boat, look for a boat with a narrower beam. Narrow beamed boats are often better at slicing through waves and chopping, whereas wider beamed boats are more likely to feel every bump and wave.

Narrow beams have less storage capacity and less room. If you live on your boat or plan on sleeping on your boat overnight, you might find a narrow boat limiting. 

Narrowboats are less stable and might feel more tippy than boats with wider beams.

If you want to trailer a boat on the road in the US, you’ll want to consider its beam very carefully. Trailerable boats should generally have a beam of 8-feet 6-inches or less. Forty-seven states only allow trailered loads with an 8’6″ beam or less.

However, a few states allow wider loads without permits, so check your state’s regulations. Anything larger would be considered a wide load and require special permits and additional considerations. If you want to trailer a boat on the roadways easily, buy a boat that is less than 8’6″ wide.

Narrowboats are long, narrow boats made for canal life. These boats have a beam that is less than seven feet to fit inside tiny locks easily.

Wide Beam Boats

Wide beam boats are more stable and less likely to capsize in waves. Modern boats are usually beamier than older, more traditional boats. Modern buyers are often looking for boats with extra space and condo-style amenities rather than small, camping-style interiors. If you are thinking about sleeping on your boat or living on your boat, consider how a wider beam will give you more space.

Catamarans are very popular cruising and charter boats. They have wide beams and offer couples and families additional space to spread out. In addition, their wide beam makes these boats very stable. These boats don’t heel as sailing monohulls do. This means that boaters can easily move around their boats while underway.

While monohulls and trawlers are often between 11 and 16 feet wide, cruising catamarans are usually between 21 and 26 feet wide. Monohulls vs catamarans is an ongoing debate, and of course, either choice involves compromise.

Trimarans are another style of popular wide beamed boat. These boats have three hulls and are even wider than catamarans. Cruising trimarans are up to 30 feet wide. If you have a larger trimaran, you’ll enjoy a stable ride but will have more trouble finding marina slips and haul-out yards.

Determining a Boat’s Beam

The easiest way to determine your boat’s beam is to refer to the boat’s documentation. If a factory-made your boat, you should have some paperwork that lists the boat’s beam. If your boat is Coast Guard documented, the boat’s measurements should be listed on that paperwork.

Measuring a boat’s beam might be easy or complex, depending on how big and complicated your boat is. If you have a 10-foot kayak, you can simply get a tape measure, find the widest part of the kayak, and note the measurement.

To measure a boat’s beam, first, you must determine the boat’s centerline. To do this, mark the center of the boat’s bow and the boat’s stern. Mark the centerline by tying a piece of string from the bow’s center to the stern’s center. Of course, if you have a sailboat or a boat with a bimini or other obstructions, this is easier said than done.

Now, find the widest point of the boat. The widest point is usually the middle of the boat or slightly aft of the middle of the boat. Now, measure the boat’s widest point, ensuring the measuring tape stays perpendicular to the centerline string.

Consider your plans for your boat while you consider your boat’s beam. If you are looking for a stable kayak for fishing, find a nice, wide kayak. A dinghy that needs to haul several people and all the goodies should have a wide beam. A wider beam will give you more living and storage space if you are living aboard .

However, if you want a fast and maneuverable kayak, look for a kayak with a narrower beam. If you want a fast dinghy, consider a narrower one. If you want to boat in narrow canals or access small marinas, find a boat that has a narrower beam. Finally, if you want to trailer your boat, look for a boat that has a beam less than 8’6″.

Of course, the answer to finding the perfect boat that’s stable, trailers, crosses oceans, and stores all the stuff is quite simple. You just need a flotilla of different boats!

Where is a boats beam?

The boat’s beam is its widest point. The widest point on a boat is usually in the middle or slightly aft of the middle of the boat. 

How do you measure a boats beam?

First, mark the boat’s centerline from bow to stern. Next, find the widest point of your boat and measure it, making sure that the measuring tape is perpendicular to the centerline.

What does beam on trailer mean?

A trailerable boat should have a beam of 8-feet 6-inches or less. Most states require wider beamed boats to have a special permit and follow special regulations. If your boat’s beam is 8’6″ or less, you won’t need a special permit to trailer it on the road.

Matt has been boating around Florida for over 25 years in everything from small powerboats to large cruising catamarans. He currently lives aboard a 38-foot Cabo Rico sailboat with his wife Lucy and adventure dog Chelsea. Together, they cruise between winters in The Bahamas and summers in the Chesapeake Bay.

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What Are the Beams of a Ship?

The structure of a ships breadth is always defined by its basic dimensional parameters: length, width, depth, and draft. Even many people who are not familiar with seafaring jargon can understand these simple terms. However, on closer inspection, these terms have a fairly clear meaning. And also classification that many people need to get used to. For example, length can be further divided into Overall Length (LOA), Length Between Perpendiculars (LBP), and Waterline Length (LWL). All these pieces of information are slightly different from each other and require a minimum of maritime knowledge to understand. 

Similarly, the draught or depth of a ship is nothing but the vertical distance. From the ship’s baseline to the waterline. And is classified as summer draught, winter drought, freshwater draught etc. Hence, every ocean-going ship has markings called loading lines/waterlines/plimsoll lines on the side hull of the ship and depending on their length. They are called summer loading line, winter loading line, North Atlantic, fresh water, etc. The corresponding waterline values ​​are expected for different draughts. Similarly, depth is the vertical height from the main deck or strength deck. Of the hull structure to an bottom of the keel plate or baseline.

What is Breadth?

What is the first thing that comes to your mind when we talk about ships breadth ? The width of a three-dimensional body is its span or associated transverse width. Simply put, this is a very perspective term. Consider a three-dimensional box or cube. While height can be easily distinguished as the vertical elevation from the plane. In which it is maintained, the definitions of length and width are open to debate. This is because length and width can be used interchangeably for the same or similar dimensions on the same plane. 

In the case of a box that is 100cm x 100cm x 50cm and 50cm high. The 100cm interval can be said to be the width or length, respectively. If the difference in dimensions is significantly small, for example, 100 cm and 120 cm. Then they can be called the width or length, respectively. However, if there is a clear difference between dimensions on the same plane. For example, one distance is 500 cm and the other 50 cm, then the difference becomes more noticeable. Thus, the distance 500 cm becomes the length, and 50 cm becomes the width or ships breadth measurement. In a ship, even someone completely unfamiliar with the subject. And also seeing a ship for the first time can distinguish between length and ships breadth .

Length Is The Visible Width From Front To Back 

When the ship is viewed from the side, and width is the width of the ship when viewed from the side, either forward or aft. When a designer or builder defines a ship, the ships breadth value indicates the maximum width of the ship, along with other measurements. As we know, in most ships, the ships breadth varies along its length. It is smallest at the front and rear and largest near the amidships, also known in shipbuilding as the parallel-centred hull.

However, in rare cases, such as patrol tugs, some research vessels and icebreakers, and some warship designs, the maximum breadth slopes forward of the amidships area and gradually decreases aft. In such cases, the defined breadth is the maximum width forward of the amidships. This maximum breadth is technically defined as the latitude of the ship. Therefore, when talking about ships in general, it is more practical to talk about breadth rather than maximum width. The breadth of a ship can now be defined variably, just like its length.

The Maximum Breadth 

It is the width measured between the two outermost points of the cross-section. For all practical purposes, this is taken to be the transverse or horizontal distance between the two ends of the exposed or reinforced deck in the centre of the ship. However, older ships sometimes had tumblehomes, and the width at the height of the main deck was less than the width below, so the maximum breadth of the main deck was not measured. As a rule, the greatest distance between the two side plates or outer ends of a ship’s hull, viewed from the side, is taken to be its maximum width. 

The value of width used to define a ship at any point in its design or construction is, for all practical purposes, taken to be this maximum width. The width at the waterline or BWL is similar to the length at the waterline or LWL. BWL is the maximum width or breadth of a ship’s hull measured at a particular waterline. In practice, BWL may be less than the maximum width, but in some cases, it may be less than the maximum width. 

Let’s Consider A Simple Example

For a barge whose hull shape is more or less uniform both lengthwise and transversely, the maximum width corresponds to the BWL. Another term, beam on centerline, or BOC, is commonly used for multihulls. For a catamaran or twin hull, the BOC is measured as the transverse distance between two hulls from their respective centerlines at the level of the exposed or starched deck. Similarly, the BOC of a trimaran is measured as the distance between two outermost hulls estimated at their respective centerlines at the level of the main deck. Now, all width and depth parameters have what are called shape and extreme dimensions.

The form dimensions do not take into account the thickness of the skin, but the extreme dimensions do take into account the thickness or dimension as well. Thus, the width or breadth of a form is the measured width of the fuselage part from the inside of the side skin at one end to the widest point or area on the inside of the panel at the other end. The extreme width also takes into account the thickness of the side skin. For most design purposes, the extreme width is taken into account. At this point, it is important to note that width is something quite different from circumference and is often confused with it. As we just explained, width is the straight line distance measured from one side to the other.

The perimeter of a particular section, on the other hand. Is the measurement of the circumference from one end of the particular section to the other. For a transverse section of a hull, the circumference is measured as the total length or extent from one deck end to the other deck end, taking into account the shape of the section. Simply put, if the outline of the hull were to be straight like a thread and projected onto a straight line, the measured length or span of that section would be the circumference. 

Circumference is directly proportional to width and vice versa. Another very simple way to understand circumference is to imagine a necklace. The width measured gives the distance from one chain to the other. However, when the necklace is unfolded, it is laid straight on a table, and the distance measured from one end to the other gives the length, in this case, the circumference.

Beams In Ship Design 

Ship beams are fundamental in every stage of design and construction. However, the length-to-beam ratio or L: B is often used to define ship designs and hull shapes. Slimmer or slender vessels such as fast passenger ferries and warships like frigates and corvettes have a higher L: B ratio. Their maximum width is less than their length. They usually have higher speed characteristics. Fuller-shaped vessels such as tankers, bulk carriers, etc., have a higher beam and, hence, a comparatively lower L: B ratio. They are usually slower ships. Container ships are halfway between slim and large ships. Since both the speed and the volume of the hull must be optimized to ensure maximum cargo loading. 

The width of a ship is also a direct measure of the lateral stability of the ship. The larger the width, the more lateral stability is due to the larger water surface. But on the other hand, a wider beam creates greater problems after capsizing. Or deck flooding since more energy is required to return the ship from its static, stable state to an upright position. A ship with a larger beam also has the option of having a larger deck area and internal tank space. The width of a ship is an important factor when navigating canals and canals. As narrow spaces and ship passage are often an issue for wider ships.

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Choosing the right beam for a multihull

QUESTION:   When assessing or designing a trimaran or catamaran, what guidance can you give to guide the choice of beam ?             

                    Lech K:  Gdansk, PL

ANSWER: An interesting question as we do see quite a variation on existing boats.

First, let’s call the Overall Beam to Length ratio B/L and the individual hull length to hull beam, L/b .

Here are a few basics to consider as inputs to your overall beam choice.

*    More beam gives more transverse stability, permitting a powerful rig to drive a boat faster, but also,       excessive beam tends to lower diagonal stability so increasing pitch-poling.    More beam also tends to allow more  fore & aft pitching.

*    More beam requires stronger connecting beams (called akas on trimarans), aggravated by the two hulls potentially being now be in different waves

*    More beam can be a problem in a marina where space is increasingly limited

*    Folding trimarans can be limited in beam due to geometric space when folded, such as:     

Transverse folding system (Farrier etc) are limited by how far down the hulls can be managed when folded.  

Swing-arm folding is limited by the overall length increase when folded.

          Hinge & latch systems are limited by what height and weight can be lifted  

*    Less beam allows a boat to heel more, thereby reducing sail exposure to side wind.

*   Less beam brings the hulls closer together, reducing beam strength requirements and weight, but potentially adding to resistance from hull-flow interaction.

*   Hulls with a high L/b ratio can be closer together than hulls with a low L/b ratio if overall stability permits.

*   As smaller boats need proportionally more displacement due to crew and structural weight, they cannot have a very high L/b ratio as they then have insufficient displacement.

------------------------------------------------------------------------------------------------------------------------------

So what do all these points finally lead to ?      Well, let’s see.

For Catamarans , the sweet spot seems to be with a L/B of 2 to 2.1.

If the beam is excessively increased, pitching and reduced diagonal stability (see dwg) start to become an issue and when such boats are lengthened to make their L/B slightly above 2, they generally become faster and have less negative issues ... but over about 2.3, their relatively lower transverse stability then starts to kick back.  

If the beam is decreased, stability drops quickly and one may start to also add wave interference between the hulls unless the boat is very light with slim hulls.

Of course, this is a simplification of things as top weight, windage, wing clearance, center of gravity, sail plan, etc etc .. all have their effects, though individually less than the important L/B ratio.

Let me give you an example of how other design criteria can move things from what may initially seem the ideal.  

Beam also has a huge effect on stability.   But the designer Jan Gougeon (then of West Systems) was an inventive guy, so he approached this design in a non-conventional way.   To achieve his first criteria .. “a fast non demountable weekend catamaran” , he needed to address the obvious lack of stability in other ways.  A low rig could work with low weight, that would then allow very slim, fast hulls.   Then he added water ballast to help keep the windward side down …. and finally, a masthead float to prevent the boat from turning turtle, where she would stay like virtually all other multihulls do IF that happens.  In this case, it was rather often as unfortunately, most sailors were not ready to adapt to this new way of sailing and with capsizes happening too quickly for most, only a dozen or so were sold.  But I did get to try the boat and felt the concept did work in the sense that the boat IS fast and also comfortable & dry, as with such long, narrow hulls, there is very little disturbance of the surface water so spray is minimal and even if the hulls are pretty close, they are too slim to create any significant cross-hull wake- interference. 

To keep the rig low (mast is shorter than the boat), she uses 2 foresails that can be furled up fast.   Those that still own one have learned to understand them and can enjoy their merits … but this is not a boat with reserve stability for sudden gusts, so you need to sail this boat more like a race dinghy and also reduce sail early.  This further means that sailing at night when you cannot see squall warnings in the sky is best avoided unless the stars are truly out for you.

But it IS an example of thinking WAY outside the box .. even if the result is not for everyone.   So ‘sweetspot L/B ratios’ do not necessarily mean they give the only solution .. just that you, as a designer, also need to work differently around the rest of the design to solve the issues you might create if you are well outside the norm.    

The lesson here is:  If you choose to go outside the norm, fully understand the implications and work around them.  You cannot ignore them and still expect success. If the designer failed at all with this radical G32 design, it was in not sufficiently educating new owners of the different sailing nuances needed to keep the boat on its feet.

For Trimarans, my studies and observations show that the preferred B/L ratio changes with boat size. 

To some degree, the same effect on diagonal stability (as for Cats) will occur with excessive beam, but with a trimaran, the two hulls in the water will be closer so it’s also important to allow for good flow between them.  So as very large racing tris can have slimmer hulls due to great length and low weight, they can have proportionally lower B/L ratios than smaller boats that need proportionally fatter central hulls just to support the displacement they need.  After all, we cannot just change things in proportion, because the weight of things (such as crew, structure etc) will not automatically get smaller for a smaller boat .. in fact it proportionally and typically, gets greater!    So smaller multihulls can often be harder to design than larger ones, where you have more space and volume to work with.    The above observations led me to plot data from good boats and create this simple little formula that fits their B/L curve pretty well.

Here is what the curve gives as a recommended B/L ratio for a sailing trimaran

                            (Sailing Trimaran) B/L ratio  = 1.48 ÷ (L  ^ 0.21)        [ Length L in feet ].

While this may initially look complex to calculate for some, it’s very easy with the right help.  Download the Mobi Calculator on your phone or tablet.  You can then add the expression x n to your basic calculator by first hitting the 3 dots [ ... ] that brings you to the Scientific Options, and then   clicking on [ x n ] that will add this feature to your basic calculator.    You can now enter the formula exactly as written, typing 1.48 ÷ (  your L value , and then x n and finally 0.21 and the closing bracket ) and then ‘ = ‘.

If you enter say L = 17 , it will give you a B/L ratio of 0.816, closely matching a W17 , while for an L of 100 ft, it will give you a B/L of only 0.562, closely matching a big ocean racing tri like Sodeb’O.

While of course you can go outside the calculated ratio, IMHO you should have a very good reason and specific justification for a deviation of more than 15% either way.   Use the list at the beginning of this article to justify your change.

For both Tris and Cats, there may be other factors that will change your design, but this gives a good starting and target point that’s based on both practical and justified design needs.

Enjoy …. playing with figures is fun ;)

mike … march 2022

ADDED NOTE ... re MOTOR MULTIS

As noted, the above ratios refer to Sailing Craft.  Without the heeling force of a sail, pure motor-tris and cats are not bound by the same needs.

A motor catamaran can have less beam, with a clean flow between the hulls now taking prominence over high beam for sailing stability, so L/B ratios of 2.5 to 3 are now more appropriate.

Hulls may need to be asymmetrical with a straighter side on the inside to avoid unfavorable hull wave interaction between them.

For a powered trimaran , overall beam should also be reduced or the motion will become uncomfortable.  (With a sailing tri, the boat is heeled with one ama out, but with a motor tri, all three hulls are immersed so wave action on the boat would be too severe if the boat is too wide) .    Amas (pontoons) now need to be narrow but deep, as a slow gentle roll of slightly greater amplitude, is more comfortable than a short quick one.  These amas (now only 40-50% of the main hull length), seem best with their center about 60-70% aft of the main hull length and need to be of fine section and relatively deep with the connecting bridge arched high above any waves, so that neither ama or aka-bridge will slam when re-entering a wave.  L/b ratios of all 3 hulls can be at their most efficient, namely 13-16 at the waterline.   The amas are now more like permanent training wheels and with a much longer central hull and no heeling force from sails, diagonal stability is no longer something to consider.    Overall beam will depend on maintaining a clean flow between the main hull and the shorter slim amas, that need to extend well down into the water, so that motion is acceptable in waves.   Typical overall B/L ratios might now be down around 0.4, becoming even less as boat design gets bigger, provided the center of gravity is kept low.

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Length Is Only One Measure of Luxury

As the Yachting industry continues to expand the number of vessels in the mega and super yacht length categories, additional measures of dimension are often overlooked.

Crew aboard luxury yachts deal with the challenges of cooking, cleaning and maintaining on a daily basis are aware of the importance of internal volume. The ease of movement and workspace comfort are driven by measures in addition to LOA (length overall).

The key to making vessels of similar length “feel big” is internal volume. The internal volume is a function of length, breadth and height. In walking the docks, comparison of side by side vessels of equal length immediately identifies the variables of beam and height. Yachts between 40 meters and 50 meters could feasibly have equivalent internal volume dependent on beam and the number of decks.

Length in and of itself can be a deceptive figure. The point along the hull where length is measured can vary. Any point other than the load line can mistakenly include bow overhangs, swim platforms, rudder dimension. The beam or breadth of a vessel is also measured on the outside of the hull mid ship at the waterline.

How the length, beam and height are combined results in the actual internal volume and the feeling of size and comfort aboard. Internal layout and the integration of alfresco areas are design challenges to give guests the impression of a bigger yacht and add to the feeling of comfort. The addition of swim platforms and sundecks can also provide an illusion of more space to the guests.

While comfort and appearance are criterion for guests, crew are impacted by the internal volume in the ease of providing service to those guests. The galley and engine room are particularly critical areas for adding volume – both for ease of use and safety. Both areas can be less than hospitable even in yachts of super length.

Design of workflow, access, storage, and movement benefits from the addition of volume provided by additional beam. The design challenge in every yacht is to have adequate service spaces without compromising the size and comfort of guest cabins.

Internal volume is measured in gross tons (GT) displacement. The internal capacity has its origin in shipping. It quantifies all space available for cargo, crew, passengers, stores and mechanics. In the t shipping industry the space that remains after subtracting internal space for everything but cargo is the space available for cargo transport – the earning power of the vessel.

Internal volume not only gives the impression of a bigger yacht, but also contributes to the earning power of the yacht by enhancing ease of use for both guests and crew.

Engineering License Changes

The MCA has restructured the engineering certifications. The MEOL course has been done away with, and the AEC course made mandatory and more thorough. Luxury Yacht Group explains all these changes, what engineers progressing through the ranks can do now, and how Y ticket holders can convert their licenses over to the structure.

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A Day in the Life Series – Chief Stewardess

For a yacht to run smoothly, it requires many working parts, and the interior department is a large component of this. The chief stewardess oversees this department and makes sure all the stewardesses onboard know what their tasks and responsibilities are. The interior department is largely in charge of the guest services whilst they are onboard, and responsible for interior maintenance of the yacht when they are not.

18 Dec 2017

A Day in the Life Of Series - Entry Stewardess

Joining the yachting industry is an exciting and daunting undertaking. In this two part interview we speak with Melanie about why she decided to join the superyacht industry, what her hopes and goals are, and what she has learnt so far as an entry level stewardess.

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Understanding Block Coefficient Of A Ship

We all know that the hull form of a vessel varies widely from design to design. A small tugboat has a different hull form from a container vessel or a tanker. The hull form of a vessel is intrinsic to the type, size, build, and of course, the utility or purpose of a vessel. 

Some vessels may be short and wide like tugs; some may be long and slender like high-speed navy frigates or destroyers. Some may be large and bluff, like tanker or bulk carriers. This hull form of the vessel depends on several physical parameters like length, breadth, or draft. Moreover, the hull form’s overall curvature makes the description complete. 

Now, from a qualitative point of view, we may describe or comment on the hull form of a vessel. But do we have any form of quantitative measure? The answer is yes. The basic parameters or attributes of a ship, like length, breadth, depth or draft, are not enough to characterise the hull-from of a vessel due to its typical curvature that is the end-point of a designer. 

So, quantitative measures comparing the different features of hull geometries under consideration with some standard reference of the convention is a good technical way of studying the hull form of any vessel. 

Thus, in the field of naval architecture, the form coefficients are of very high importance. These form coefficients quantitatively describe a hull with a reference physical or overall geometric benchmark from a design and a mathematical point of view. These form coefficients are applicable in every area, like structure, stability, hydrostatics, resistance, propulsion, seakeeping , manoeuvring, etc. 

Some commonly used form coefficients are Block Coefficient, Waterplane Coefficient, Prismatic coefficient, and Midship Section Coefficient. Read on to find out about the most basic of them, which is the Block Coefficient. 

What is a Block Coefficient?

Now, we know that a vessel floating in water displaces a certain volume of water which imparts an opposite reaction known as buoyancy which keeps the body afloat. This upwardly acting buoyancy equals the weight of the underwater volume displaced by the hull from the first principles. 

This weight of the displaced water is also mathematically equivalent to the vessel’s structure and is defined as the displacement of the vessel. The displacement is a characteristic of the hull form and it depends on the physical features of the hull, as this only translates to the volume of water being displaced at given conditions.

Once again, as we have said, the hull form is very typical for a particular vessel. So, a measure or an index of its understanding can be well deduced if we physically compare it with a simple, cuboidal block at the same levels of immersion. What does that mean? We all know, for a vessel, along with a definite length and breadth, the draft defines the height or the level till which the hull is underwater. 

Also, recall that the design breadth of the vessel is the maximum breadth, usually at midships for conventional designs. So, the underwater volume of displacement at the same draft of an equivalent block or cuboid would be the product of the vessel’s length, its width or breadth, and the present draft at which it is floating. The length used in the denominator term is the measured Length between Perpendiculars or LBP for all practical purposes. 

Hence, the block coefficient is the mathematical ratio between the actual volume displacement of the given vessel and the volume displacement of an equivalent cuboid having the same dimensions at that particular draft.

Mathematically, it is the volume displacement measured for that vessel divided by the volume of the rectangular cuboid of equal length, draft, and breadth. As per the figure below, in a visual sense, if a cuboidal or rectangular box is imagined to be exactly fitted around the submerged portion of the hull, it is equal to the ratio of the space occupied by the hull volume to the ratio of the circumscribing box. 

The value of the block coefficient or C B always falls in the range from 0 to 1. This value essentially defines the fullness or fineness of the hull form. For higher values of C B , the vessel’s hull form is said to be fuller, and for lower values, it is said to be finer. For example, military fighter vessels like high-speed corvettes or frigates have block coefficients as low as 0.5-0.6. 

On the other hand, fuller-form cargo vessels like bulkers and tankers have block coefficients in the range of 0.8 to 0.9. In near-ideal cases, a dumb barge or a pontoon has a block coefficient of nearly one as they closely resemble the rectangular cuboid with or without some minor deviations. 

So, what brings about this block coefficient ratio for vessels?

The answer lies in the nature of the hull form once again and all the curvatures in geometry like deck outlines, bottom curvatures, turns of bilges or the bottom region, shapes of the side shell-like flares and tumblehomes, and hull shape characteristics in the longitudinal direction like the forward or aft rakes, rises, or other various forms typical to the hull form. In conventional vessels, the maximum amount of deviation is observed towards the forward and aft regions of the hull for all practical purposes. 

However, in some typical designs like escort tugs, some offshore vessels and research vessels, or several ice class ships, where there is a higher level of hull curvature towards the front of the midship region, that is, the vessel’s longitudinal centre of gravity being skewed forward, the block coefficients may be fairly high, and the block coefficient value is mostly affected by the part of the hull aft. 

For passenger vessels and containerships, where there is a requirement for higher speed and hence have finer entrances shoulders, have a relatively lower value of block coefficient, not more than 0.7-0.75. 

Uses of Block Coefficient

First and foremost, the block coefficient is used to have an understanding of the nature of the hull form designers, viz., the hull is finer or fuller form. Consequently, from a resistance point of view, the resistance of the hull is directly proportional to the fullness and vice-versa. This, in turn, is related to the speed of the vessel. Hence, to achieve a higher value of speed, the block coefficient must often be altered by the designers. 

Similarly, to reduce power consumption or achieve higher propulsive efficiency, the block coefficient is an important parameter that is considered by designers. On the other hand, the block coefficient also essentially translates to the usable volume or tonnage of the vessel. Hence, while considering all the factors of resistance and powering, this should also be optimised accordingly. 

However, in high-speed vessels with low block coefficients, the displacement-to-rule length ratio should be kept low to avoid high degrees of wave resistance.

You may also like to read-

• What are Draft Lines Of Vessels?
• Types of Rudders Used For Ships
• Understanding Intact & Damage Stability of Ships
• How Shipyards Can Adopt Advanced Outfitting?

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About Author

Subhodeep is a Naval Architecture and Ocean Engineering graduate. Interested in the intricacies of marine structures and goal-based design aspects, he is dedicated to sharing and propagation of common technical knowledge within this sector, which, at this very moment, requires a turnabout to flourish back to its old glory.

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M.B. Marsh Marine Design

Length-beam ratio.

L/B = length divided by beam.

Units: Dimensionless.

Usually, the waterline dimensions L WL and B WL are used for monohulls, or for a single hull of a multihull.

What it's used for

Performance.

Larger L/B indicates a slimmer hull. This usually implies less wave-making resistance, and thus more efficient high-speed performance, but also suggests reduced load-carrying ability for a given length.

If a boat can plane, smaller L/B often suggests more efficient performance at low planing speeds. The balance generally tilts in favour of high L/B for fast boats.

Typical ranges of L/B are:

2 to 4 - Small to mid-size planing powerboats.

3 to 4 - Most small to mid-size sailboats and motor yachts, the longer ones generally having higher L/B. Some "skimming dish" racing sailboats also have L/B in this range; their wide beam gives them more initial stability so that they can fly larger sails.

4 to 6 - Fairly long and lean for a monohull. Some large, efficient long-range cruisers fall in this range, along with many racing monohulls.

6 to 10 - Large freighters; main hulls of cruising trimarans; a few very portly cruising catamarans; the lightest and slimmest of large sailing monohulls.

10 to 16 - Fast cruising cats and tris; a few racing multihulls.

Over 16 - Racing multihulls. Such high L/B is conducive to very light, low-drag hulls for race boats, but makes it very hard to get enough room inside the hulls for equipment or living space.

Living Space

If a boat is going to spend most of its time in a marina or at anchor, relatively low L/B implies a larger, more spacious interior and increased carrying capacity when compared to slimmer competitors of the same length. For a boat that must entertain guests at the dock but will rarely be used in rough weather or at high speeds, this may be a significant advantage. The slimmer boat, though, will generally have the advantage when fuel is expensive or when the weather picks up.

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Position of beam/breadth

Discussion in ' Boat Design ' started by Flysafe , Aug 20, 2011 .

Flysafe Junior Member

Hello everyone, I wonder if anyone can help me with a question I have, which of the two terms is more appropriate beam or breadth? On a boat like this picture where is the beam? I Already checked on wikipedia but they have two ways for the same thing. If someone could advise me a book or some kind of information which explains the beam on yachts, the problem is that I'm starting a new design and this boat has a very sharp angle. Thank you all  

Attached Files:

00 sem título.jpg.

PAR Yacht Designer/Builder

Both beam and breadth mean width. The boat's beam is it's width and the breadth of the boat is also it's width. How can it be, that you are starting a new boat (assumed) design and don't know what or where the beam is located?  

JRD Senior Member

Hi Flysafe Maximum beam (breadth) tends to be at the sheerline (top). Then there is the maximum beam at the chine (sharp angle) and the waterline beam, which is not much different from th the beam at the chine as a rule. In reality these are all just offsets from centreline at various height which make up the 3D matrix which is any kind of boat, but the quoted beam is ussually the maximum. This is for your model boat design, right? Im sure you will find all the definitions if you look long enough on google, or look for a book on power boat design, Good luck with your design.  

viking north VINLAND

Breadth--is old English for beam as is vessel for boat, spars--stem--jumbo (big jib) canvas(sails) bum boat, donkey engine, and so on, common old terms used in my former homeland of NFLD,(Newfoundland). As previously posted beam is now used commonly in place of breadth. The term possibly derived from deck beam a cross sectional framing structure on a vessel I.E.whats the max length of her deck beams and to shorten it whats her max beam. Now days of course with more precise engineering one has to be more specific and the results are beam(meaning max. width at the sheer)(gunnels) , waterline beam, and if using chines likewise beam at the chines could be a term. Oh! forgot then there's MR. Beam-- A yacht is not determined by the vessel but by the care and love of her owner--  

Hello everyone, Thank you all for the replys. PAR said: ↑ Both beam and breadth mean width. The boat's beam is it's width and the breadth of the boat is also it's width. How can it be, that you are starting a new boat (assumed) design and don't know what or where the beam is located? Click to expand...

gonzo Senior Member

Wikipedia is not the best source of information. Except for usually being at the top, it is suspect for accuracy.  

Wikipedia usually gets the basics right, but can be off on the details, unless of course it's about Sara Palin's latest gaff . . .  

gonzo I agree with you about the information from wikipedia PAR My question come up because of the various definitions that wikipedia gave. I do not need to look at the basics in wikipedia, I'm a little further than the basics, that's why I do my questions here, and only when I can not find anything anywhere. Thank you all.  

Ike Senior Member

Actually various comparisons of Wikipedia and well known encyclopedias such as Britannica have shown that Wikipedia is actually just as accurate http://news.cnet.com/2100-1038_3-5997332.html What Flysafe needs to do is go to the library and get a book on Naval Architecture or Yacht Design to learn the terms.  

Hello Ike, Thanks for your reply. My problem is not with the terms themselves but sometimes with the position they occupy in the boat, as you can see the response of the JRD gave, there is a amount of beams and the of information from wikipedia shows two different things, hence my question did come. Your idea is very good to buy a good book then give me a few titles for small yacht please, as you know there a lot and I have to buy through the Internet. Thank you.  

rasorinc Senior Member

http://www.glen-l.com/building-your-own-boat-where-to-start/ Click on Gossary of Terms  

Principles of Yacht Design by Lars Larsson and Rolf E Eliasson. International Marine, 1994. You can get it through Amazon  

Flysafe--don't concentrate on knowing and getting all these boatbuilding nautical terms down pat. Get the few hull term basics down: length, beam, waterline, bow, stern, bilge, keel, deadrise, entry, exit, displacement, ballast, and a few associated with the superstructure and basic sloop standing and running rigging terms. As you read and work with these craft you'll pick up the other names thru osmosis and look up new un known names. As a new person in the field you will overwhelm yourself Better to spend that time learning how to build something basic. Hey being Portugese it's genetic-- the greatest seafarers and navagitors on earth ask any Newfoundlander ---Geo.  

jehardiman Senior Member

FWIW, I was taught that the "Breadth" of the vessel was more of a legal term along with the "Length on Deck" and "Depth of Hold" that were involved in the historical formulation of the tonnage measurement. The Breadth of a vessel was the widest part of the hull, measured from the inside of the shell planking or frame face. This is why it is called the "Half-Breadth Plan", because the lines drawing would be to the outside face of the frame that would be lofted, the shell applied after the frames were setup. "Beam" on the other hand, was any athawartships mesurement. Moulded Beam was identical to the Breadth. Maximum Beam was the maximum width across the outside of the vessel including shell, wales, sponsons and wings (and today excludes all moveable rigging items such as gangways and davits). Spared Beam or Extreame Beam includes the spars and moveable items. Similarly, Waterline Beam is the maximum width of the vessel at the waterline.  

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Jehardiman-- sounds good to me--legal terms generally being expressed in old English -- as an example i have included documentation of my Great/Great/Great Grandfathers vessel (a heel tapper schooner) he built in Newfoundland and registered with the British Admirality--legal tems and old English for sure--Geo. P.S. you might have to enlarge to read A yach is not defined by the vessel but by the care and love of her owner--  

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Yacht, IMO 1012531

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The current position of MY AMADEA is at North America West Coast reported 2 mins ago by AIS. The vessel is en route to . , and expected to arrive there on Sep 12, 19:12 . The vessel MY AMADEA (IMO 1012531, MMSI 368260150) is a Yacht built in 2016 (8 years old) and currently sailing under the flag of United States (USA) .

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Recent port calls, vessel particulars.

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Address Website - Email - Address Website Email ISM Manager - Address - Website - Email - P&I Club - Classification Society   MY AMADEA current position and history of port calls are received by AIS. Technical specifications, tonnages and management details are derived from VesselFinder database. The data is for informational purposes only and VesselFinder is not responsible for the accuracy and reliability of MY AMADEA data. 278 IMAGES HM Yacht Alexandra. Profile; Half Breadth Plan; Body Plan Sections 1910 What is tonnage measurement for yachts? How to Read a Ship Plan Model Yachts: How to Design and Build Them. Part I YACHT: VALKYR, 1882. /nSheer plan and half-breadth plan of the 'Valkyr Sheer lines, longitudinal half-breadth and body of three unnamed VIDEO MegaYacht Sunrays Oceanco [4K 50p] (Ravi Ruia) 2019 Awatea Yacht Bodø Havn MERCHANT NAVY HANJIN BRUSSELS CONTAINER SHIP VIDEO St. Eval Super Yacht Sunrays (Details & Toys) Oceanco 2021 AFRAMAZ RIVER CRUDE OIL TANKER SHIP FOR MERCHANT NAVY COMMENTS Beam (nautical) Beam (nautical) Graphical representation of the dimensions used to describe a ship. Dimension "b" is the beam at waterline. The beam of a ship is its width at its widest point. The maximum beam (B MAX) is the distance between planes passing through the outer sides of the ship, beam of the hull (B H) only includes permanently fixed parts of the ... Understanding The Beam Of A Ship Understanding The Beam Of A Ship A ship structure is always defined in terms of its basic dimensional parameters such as length, breadth, depth, and draft. Many people unfamiliar with technical maritime terms also understand these simple terms. However, delving deeper, these terms have somewhat clear implications and classifications that many people need to become more familiar with. What Is the Beam on a Boat? (Fully Explained) What is the beam on a boat? It refers to the entire breadth of the vessel, with the widest distance between the hull's gunwales or the port and starboard sides as the main points of reference. This is the simplest beam boat meaning. What Is Boat Beam? Understanding the Basics of Boat Beam Measurement Boat beam, also known as the width or breadth of a boat, is an essential measurement in the design and construction of a vessel. Understanding boat beam is critical for anyone looking to purchase, operate, or design a boat. PDF Guide for Building and Classing Yachts 2021 Breadth used in 3-2-1/1.1.1 for yachts which have flare or tumblehome, is the mean breadth of the waterline breadth and the maximum breadth between the waterline and main deck at the longitudinal center of flotation (LCF). 7 Depth. 7.1 Motor Yachts. D is the molded depth, in meters (feet), measured at the middle of the length L, from the molded ... What is the Beam of a Boat? A Clear Explanation The terms beam and breadth are often used interchangeably to refer to the width of a ship. However, technically speaking, beam refers to the maximum width of a ship at its widest point, while breadth is the measurement taken at the widest point of a ship's hull. Geometry The other line in the lower part of the half breadth plan is the curve of sectional areas, representing the longitudinal distribution of the submerged volume of the yacht. What Is Moulded Depth Of A Ship? Subhodeep Ghosh December 26, 2022 Naval Architecture We know basic parameters like length, breadth, depth, draft, etc., primarily denote a vessel. From a geometrical point of view, all these parameters essentially define the size of the vessel and, up to some extent, the vessel's hull form. What is a Boat's Beam? Your Guide to the Beam on a Boat A boat's beam is the widest point of the boat. It's an important measurement to know, just like the length of your boat is vital to know. Like many things in boat design, the beam is one of the tools that yacht designers tinker with to get just the right characteristics. But it also has lots of implications for boat owners too, so let's take a closer look at a boat's beam. Ships Breadth: A Comprehensive Guide Discover the significance of a ships breadth design and navigation. How the beam affects stability, speed, and performance in this guide. Boat Beam [What Is It and Its Relation to A Boat's Stability] It is the overall width of a boat, measured at the widest portion of the nominal waterline. The boat beam largely determines its stability on the water. Generally, the wider the beam, the more stable the boat. To measure a boat beam, the boat is measured at the widest part, from the left side (port) to the right side (starboard). Length to Beam ratios for Multihulls Here is what the curve gives as a recommended B/L ratio for a sailing trimaran. (Sailing Trimaran) B/L ratio = 1.48 ÷ (L ^ 0.21) [ Length L in feet ]. While this may initially look complex to calculate for some, it's very easy with the right help. Download the Mobi Calculator on your phone or tablet. You can then add the expression xn to ... Hull (watercraft) Hull (watercraft) A hull is the watertight body of a ship, boat, submarine, or flying boat. The hull may open at the top (such as a dinghy), or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. The line where the hull meets the water surface is ... The size of a yacht is measured by length, width and height The internal volume is a function of length, breadth and height. In walking the docks, comparison of side by side vessels of equal length immediately identifies the variables of beam and height. Yachts between 40 meters and 50 meters could feasibly have equivalent internal volume dependent on beam and the number of decks. Understanding Block Coefficient Of A Ship Also, recall that the design breadth of the vessel is the maximum breadth, usually at midships for conventional designs. So, the underwater volume of displacement at the same draft of an equivalent block or cuboid would be the product of the vessel's length, its width or breadth, and the present draft at which it is floating. Ship measurements Definitions. Beam - A measure of the width of the ship. There are two types: Beam, Overall (BOA), commonly referred to simply as Beam - The overall width of the ship measured at the widest point of the nominal waterline. Beam on Centerline (BOC) - Used for multihull vessels. The BOC for vessels is measured as follows: For a catamaran: the ... Length-beam ratio Typical ranges of L/B are: 2 to 4 - Small to mid-size planing powerboats. 3 to 4 - Most small to mid-size sailboats and motor yachts, the longer ones generally having higher L/B. Some "skimming dish" racing sailboats also have L/B in this range; their wide beam gives them more initial stability so that they can fly larger sails. Position of beam/breadth PAR Yacht Designer/Builder Both beam and breadth mean width. The boat's beam is it's width and the breadth of the boat is also it's width. How can it be, that you are starting a new boat (assumed) design and don't know what or where the beam is located? PAR Plans PAR's Building Tips and Tricks PAR, Aug 21, 2011 #2 Joined: May 2010 Posts: 232 MY AMADEA, Yacht Vessel MY AMADEA (IMO 1012531, MMSI 368260150) is a Yacht built in 2016 and currently sailing under the flag of United States (USA). THE 5 BEST Nizhny Novgorod Boat Rides & Cruises Set sail on your destination's top-rated boat tours and cruises. Whether it's an entertaining and informative boat tour or a relaxing sunset dinner cruise, these are the best Nizhny Novgorod cruises around. Looking for something more adventurous? Check out our list of must-do water activities in Nizhny Novgorod. See reviews and photos of boat tours & water sports in Nizhny Novgorod on Tripadvisor. Yarmarka Zhivotnykh Welcome to the" animal Fair " in Nizhny Novgorod! Our Fair is located on an area of more than 350 sq. m. 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