Posting Rules | post new threads post replies post attachments edit your posts is are code is are are are | Similar Threads | Thread | Thread Starter | Forum | Replies | Last Post | | Abrain | Seamanship & Boat Handling | 125 | 12-04-2024 07:55 | | artisguru | Multihull Sailboats | 61 | 08-12-2023 05:45 | | Arthurgifford | Monohull Sailboats | 69 | 22-02-2023 19:07 | | samson | General Sailing Forum | 11 | 20-03-2011 13:05 | Privacy Guaranteed - your email is never shared with anyone, opt out any time. Log in or Sign upYou are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser . Transom clearance questionDiscussion in ' Boat Design ' started by k_skit , Sep 17, 2009 . k_skit Junior MemberHi! I am trying to design a sailing boat for myself. The basic figures are to be: LOA= 8m LWL= 7,7-7,9m B= 2,54m Loaded Displacement= 2,6t SA= 40-42 sq. m. Disp/LWL ratio about 140 gives a chance for this boat to reach planning (at least theory tells that ). Now I am trying to develop the hull. I am amateur and have no ability to use towing tests or flow simulation. Could somebody tell me how to settle the distance between lowest point of transom and LWL in order to have a longest possible LWL and still avoid separation at the stern wave? Is there any rules on thumb? Hope somebody will help me... PAR Yacht Designer/BuilderRead this: You can purchase it here, plus there are several other titles that will be of great help. http://books.boatdesign.net/boat/books.cgi?Operation=ItemLookup&ItemId=0071487697&locale=us Dear PAR, I am fully agree that any novice should read this book first. I have studied two editions of it (edition 2 and 3). But I have not found the answer to my question. Still thank you for the attention. Displacement? Plane? Target S/L? you question is a bit ambiguous. To PAR: The total displacement is 2,6 ton (fully loaded); The target Speed/Length ratio is 1,4 Eric Sponberg Senior Memberk_skit said: ↑ Could somebody tell me how to settle the distance between lowest point of transom and LWL in order to have a longest possible LWL and still avoid separation at the stern wave? Is there any rules on thumb? Hope somebody will help me... Click to expand... Maybe it would be more helpful if we had more information about the design k-skit. Other then some very general observations, such as you're not really up on plane at 1.4 S/L or desirable buttock angles, I'm still at a lose as to what you're interested in. Some images of your design may shed some light on her potential. Dear Mr. Sponberg Dear PAR, Sorry for the late answer - I was on the business trip and have had no time to think it over. Actually I have modeled approx 30 different hulls while I was reading Larsson/Eliasson book. But the actual hull is not designed yet. I will do as Mr. Sponberg told in his post. After all this is to be an amateur boat intended for cruising, not for races. Thank you and best regartds, Converting 20 inch transom to 25Transom rebuild / redesign. Transom Load Advice Neededtransom angleTransom Pods - Flotation and Extended Planing SurfaceIs a eurotransom more efficient, fasterTransom measurement questionoptimal relative transom width for low power planing hull skiff?Transom angle for outboard boatsTransom reinforcement question- No, create an account now.
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William Hay, WriterWilliam Hay, winner of 3 Kenneth R. Wilson Writing Awards and Folio Award, Canadian Author Association member,author of Caesarean Section and Love Between the Sacred and Profane poetry books, and Psychiatry and Addiction, Personal Perspective book, magazine short story and prose columnist. Saturday, June 28, 2014Volvo penta d2-40 marine diesel engine, sailboat heart and love. well I guess there are 2 sides to each conflict as you said separate with love your Volvo Engine sure looks good and well laid out too very best wishes Post a Comment Love Between the Sacred and ProfaneMy Blog ListBlog archive. - ► August (9)
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VESSEL REVIEW | Sinichka – Electric commuter boats designed for Russia’s Moskva RiverA series of three new electric monohull commuter ferries have already begun operational sailings on the Moskva River in the Russian capital Moscow. Built by Russian shipyard Emperium, sister vessels Sinichka , Filka , and Presnya – all named after rivers in Moscow – are being operated by the Moscow Department of Transport and Road Infrastructure Development (Moscow Deptrans). They are the first units of a planned fleet of 20 vessels that will serve the capital city and other nearby communities. The new ferry system will be the water transport system to be operated on the Moskva River in 16 years. Each vessel has a welded aluminium hull, an LOA of 21 metres, a beam of 6.2 metres, a draught of only 1.4 metres, a displacement of 40 tonnes, and capacity for 80 passengers plus two crewmembers. Seating is available for 42 passengers on each ferry, and the main cabins are also fitted with USB charging ports, wifi connectivity, tables, toilets, and space for bicycles and scooters. The cabin layout can be rearranged to allow the operator to adjust the distances between the seats and to install armrests of varying widths. An open upper deck is also accessible to passengers and is the only area on each ferry where smoking is allowed. The ferries are all of modular construction with each ferry's wheelhouse, main cabin, and other structural elements being built as complete, separate components. This enables the ferries to be easily dismantled for transport to anywhere in Russia by rail and then quickly re-assembled within seven days. The ferries are also ice-capable. Recently completed operational trials on the Moskva showed that the vessels can also easily navigate under mild winter conditions with broken surface ice, though year-round operations are planned for the entire fleet. The ferries are each fitted with 500kWh lithium iron phosphate battery packs that supply power to two 134kW motors. This configuration can deliver a maximum speed of 11.8 knots, a cruising speed of just under 10 knots, and a range of 150 kilometres. Emperium said the transfer of rotation of electric motors to the propeller is carried out by direct drive. As a propulsion installation, a pulling rotary propeller-steering column with double screws is used. The installation of double pulling screws, with similar power, allows an operator to increase the efficiency of the propulsion system to deliver a slightly higher speed or to reduce energy consumption. This arrangement also provides the ferries with enhanced manoeuvrability necessary for navigating in close quarters. The batteries themselves have projected service lives of 10 to 12 years and are fitted with safety features such as built-in fire extinguishers and gas vents. Quick-disconnect features allow the batteries to be easily removed for replacement or maintenance. Some of our readers have expressed disquiet at our publication of reviews and articles describing new vessels from Russia. We at Baird Maritime can understand and sympathise with those views. However, despite the behaviour of the country's leaders, we believe that the maritime world needs to learn of the latest developments in vessel design and construction there. Click here to read other news stories, features, opinion articles, and vessel reviews as part of this month's Passenger Vessel Week. | | Type of vessel: | Commuter ferries | Flag: | Russia | Operator: | Moscow Department of Transport and Road Infrastructure Development, Russia | Builder: | Emperium, Russia | Hull construction material: | Aluminium | Length overall: | 21 metres | Beam: | 6.2 metres | Draught: | 1.4 metres | Propulsion: | 2 x 134 kW | Maximum speed: | 11.8 knots | Cruising speed: | 10 knots | Range: | 150 kilometres | Batteries: | Lithium iron phosphate, 500 kWh | Accommodation: | Cabin; toilets; bicycle/scooter area | Crew: | 2 | Passengers: | 80 | Operational area: | Moskva River, Russia |
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- Westerly Discus 33 Sailboat Specs
The Westerly Discus 33 Specs & Key Performance IndicatorsThe Westerly Discus 33 sailboat, designed by British naval architect Jack Laurent Giles, was built by Westerly Marine Construction Ltd. in Waterlooville, Hampshire, UK. Published Specification for the Westerly Discus 33Keel & Rudder Configuration: Fin keel with rudder on partial skeg Hull Material: Fiberglass (GRP) Length Overall: 10.14m (33'3") Waterline Length: 8.68m (28'6") Beam: 3.40m (11'2") Draft: 1.68m (5'6") Rig Type: Masthead Sloop Displacement: 6,854 kg (15,097 lbs) Ballast: 2,793 kg (6,047 lbs) Water Tank Capacity: 204 litres (45 gallons) Fuel Tank Capacity: 136 litres (35 gallons) Hull Speed: 7.15 knots Designer: Jack Laurent Giles Builder: Westerly Marine Construction Ltd. Year First Built: 1979 Year Last Built: 1984 Options, Alternatives & VariationsThere were later versions of the Westerly Discus 33 sailboat produced. The primary variations included: - Bridge Deck Version: Introduced in 1980, this version featured an aft cockpit with a broad, high bridge deck between the cockpit well and the main hatch. This design provided a more sheltered lounging space but made ingress to the saloon more awkward.
- Centre Cockpit Version: This version was more similar to the original Westerly 33, featuring a walkthrough to the aft cabin instead of a cockpit hatch. It offered a different layout and slightly different handling characteristics.
- Rig Options: While the original Discus 33 was primarily a masthead sloop, later versions also offered a ketch rig as an option.
Sail Areas & Rig DimensionsSail Area (100%): 48.87m² (526ft²) I: 13.09m (43'0") J: 4.21m (13'10") P: 11.58m (38'0") E: 3.13m (10'3") Published Design Ratios The Key Performance Indicators (KPIs)The following analysis of the design ratios gives an indication of the boat's likely sailing characteristics, but see the 'Notes of Caution' below : - Sail Area/Displacement Ratio (13.83): This ratio is below 16, indicating that the Westerly Discus 33 is relatively underpowered. It suggests that the boat will not have high performance in terms of speed and may perform slower, particularly in light wind conditions, than other similar-sized sailboats with a higher ratio.
- Ballast/Displacement Ratio (40.05%): At just over 40%, this ratio indicates a stiff and powerful boat. The Westerly Discus 33 will be able to stand up to the wind effectively, contributing to a stable and upright sailing experience, which is particularly beneficial in stronger wind conditions.
- Displacement/Length Ratio (291.76): This places the boat in the heavy displacement category (275-350). A heavy displacement boat typically offers a smoother and more comfortable ride, can carry more stores and equipment, and will be more forgiving in rough sea conditions but sacrifices speed and agility.
- Comfort Ratio (31.38): With a comfort ratio in the range of 30 to 40, the Westerly Discus 33 is expected to have a reasonably sedate motion, suitable for moderate bluewater cruising. This means it should provide a more comfortable experience for the crew during long passages, reducing the likelihood of motion-induced discomfort in choppy sea conditions.
- Capsize Screening Formula (1.81): A capsize screening value of 1.81 indicates good bluewater capability, as it is well under the threshold of 2.0. This makes the Westerly Discus 33 a suitable choice for ocean passages, with lower vulnerability to capsizing even in rough seas.
Summary: The Westerly Discus 33 is a well-balanced bluewater cruiser designed with comfort and safety in mind rather than high performance. It is underpowered for competitive sailing, but its stiffer build and heavy displacement offer stability and a smooth ride in various sea conditions. The moderate comfort ratio ensures that it will be reasonably sedate and comfortable over long distances, making it a good choice for sailors planning extended offshore and ocean voyages. Here's how to calculate the KPIs yourself - without having to wrestle with the mathematics... Design Ratios: Notes of Caution... - The Sail Area/Displacement Ratio (SA/D): This ratio provides an estimate of the sail power relative to the boat's weight, which can indicate potential speed in various wind conditions. But i t doesn't account for the efficiency of the sail plan, the rigging, or the skill of the crew. Real-world performance can vary significantly based on these factors.
- The Ballast/Displacement Ratio (B/D): This ratio gives an idea of the boat's stability and stiffness, which is crucial for handling and safety. But it doesn't consider the distribution of the ballast or the hull shape, both of which can greatly affect stability. A high B/D ratio alone doesn't guarantee a stable boat if the ballast is poorly distributed.
- The Displacement/Length Ratio (D/L): This ratio helps predict the boat's speed potential and its behaviour in different sea conditions. But it doesn't account for the hull design or the boat's overall weight distribution. Two boats with the same D/L ratio can perform very differently if their hull shapes are different.
- The Comfort Ratio (CR): This ratio estimates the boat's motion comfort in a seaway, which is important for long passages. But it doesn't consider the boat's interior layout, which can also affect comfort. Additionally, personal tolerance to motion varies, so a boat that is comfortable for one person might not be for another.
- The Capsize Screening Formula (CSF): This formula assesses the likelihood of a boat capsizing in heavy seas, which is critical for offshore safety. But it doesn't take into account the boat's handling characteristics or the skill of the crew. A boat with a low CSF can still capsize if poorly handled in severe conditions.
General Limitations - Static Nature: These ratios are static measurements and don't account for dynamic factors like wave action, wind gusts, or crew actions.
- Simplification: They simplify complex interactions into single numbers, which can be misleading. Real-world performance is influenced by a multitude of factors that these ratios can't fully capture.
- Context: The context in which the boat is used (e.g., coastal cruising vs. offshore racing) can greatly affect how these ratios should be interpreted.
In summary, while these ratios provide valuable insights into the theoretical performance characteristics of a sailboat, they should be used as part of a broader assessment that includes practical experience, sea trials, and expert advice. Other sailboats in the Westerly range include:The above text was drafted by sailboat-cruising.com using GPT-4 (OpenAI’s large-scale language-generation model) as a research assistant to develop source material; we believe it to be accurate to the best of our knowledge. Recent ArticlesApla 42 Sailboat Specs & Key Performance IndicatorsAug 30, 24 02:51 AM Ovni 445 Sailboat Specs & Key Performance IndicatorsAug 29, 24 03:44 AM Catalina 34 Sailboat Specs & Key Performance IndicatorsAug 29, 24 12:14 AM Here's where to:- Find Used Sailboats for Sale...
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Heavy and Ultra-Heavy Displacement Hulls. With Displacement/Length ratios of 360 plus, ultra-heavy displacement hull styles have fewer devotees these days, though for passionate cruising traditionalists it's de rigueur. Heavy displacement sailboats of this type will have a full (or long) keel, which will bring with it some benefits - and some ...
Allures 51.9 price: €766,000. The Ovni 370 is another cunning new aluminum centreboard offering, a true deck saloon cruiser for two. The designers say the biggest challenge was to create a ...
No longer, it seems, does the aspiring bluewater cruiser seek out slow, heavy-displacement boats with tiny cockpits and conservative rigs. As the mass-market builders produced ever-bigger models over the last 20 years, and evolving technology improved their engineering and durability, so owners began using these boats for ever-longer passages.
With a fin keel, reasonably heavy displacement, and solid build, open ocean cruising is made comfortable in the Valiant 40. The Valiant's trademark is the canoe stern, something Perry has carried over into many of his designs. The boat's performance sets it apart from the more traditional heavy-cruisers, and it still has many admirers.
A displacement hull is a boat hull design that uses buoyancy to support its weight. It lies partially submerged and displaces water when moving, hence its name. The amount of water it displaces is equal to its weight. It's very stable in rough waters. That's why this design is widely used on cruisers and sailboats.
The Ingrid 38 is a double-ended sailboat that was originally designed for wood construction in 1938. In 1971, Bluewater Boat Co. began building a fiberglass version. The design proved hugely popular and more than 140 were built. With a full keep and heavy displacement, the Ingrid 38 epitomizes the traditional bluewater cruiser.
The Ballast/Displacement Ratio of 50.0 indicates that the boat is likely to be stiff and powerful, standing up well to her canvas in a blow and helping her to power through the waves. With a Displacement/Length Ratio of 314, the Ericson 39 falls into the category of a heavy displacement boat. This suggests that the boat can be loaded with all ...
There are several reasons that — all other factors held constant — a heavy-displacement sailing yacht is, on average, slower than a light-displacement vessel. But there being a necessary connection between heavier displacement and greater frictional resistance resulting from increased wetted surface is not one them.
The Frances 26 is a 1980s Chuck Paine designed double-ender. This eye-catching small double-ender was designed by Californian Chuck Paine in the mid-1980s but built in the UK by Victoria Marine. It's an ideal short-handed boat, with accommodation to match, along with sufficient displacement to give the solid feel that many long-keel ...
A mong the dockside pundits, the discussion of light vs. heavy displacement usually revolves around the ability of a cruising sailboat to carry the necessary provisions and gear for extended cruising. I would like to consider the question from another angle: appearance and cost. L ight displacement boats have some real advantages. Up to a certain point, lighter displacement saves money, both ...
Few if any sailboats are built to this displacement category these days - but they remain popular with some long-distance sailors. 4. Ted Brewer's Comfort Ratio of 42.9 suggests that crew comfort aboard a Westsail 32 in a seaway is similar to what you would associate with the motion of a heavy bluewater cruising boat.
The design is a moderately heavy displacement cruising boat so it takes a bit of wind to get her going. However, like most cruising boats of this class, sailing five to six knots in 10 to 12 knots of wind on a beam reach can provide 140-mile-plus days in the tradewinds. Although the sheeting angles have been tightened as the tracks have been ...
A more moderate displacement boat, such as the Hallberg Rassy 342 or Dufour 32 Classic, will have a value in the range 5 to about 5.5; whilst a racing boat may a value of up to, and even over, 7. A heavy displacement cruising boat with a fair run aft is less affected by additional weight
The Voyager 35, a heavy displacement pilothouse cruising boat was designed by Angus Primrose and built in the UK by Trident Marine. ... The Biscay 36, a heavy displacement aft-cockpit cruising yacht, was designed by Alan Hill and built in the UK by Robert Ives Ltd together with Falmouth Boat Construction Ltd.
Re: Docking long keel/heavy displacement yachts. Absent a bow thruster, your only turning tools are rudder, prop wash directed over rudder, and prop walk. Heavy displacement sailboats often have small engines with small props. You must learn to manage the tools you have, though there is no magic button.
I am trying to design a sailing boat for myself. The basic figures are to be: LOA= 8m LWL= 7,7-7,9m B= 2,54m Loaded Displacement= 2,6t SA= 40-42 sq. m. Disp/LWL ratio about 140 gives a chance for this boat to reach planning (at least theory tells that ). Now I am trying to develop the hull.
More cylinders is better. Cylinders are things of beauty and joy. In a jam I've run the Yanmar on 2 cylinders. The cylinder diameter /stroke is 77/81 mm. The compression ratio on the D2 -40 Volvo is 23.5:1. Engine revolutions are 2800 to 3200 rpm. The crankshaft power is 29.1 KW. This is all very good.
Westerly Seahawk 35; Westerly Kestrel 35; Westsail 32; Willard 30/8t; X-332; X-342; Medium sized cruising yachts like these are capable of serious offshore passage making, whilst being reasonably economic to maintain and operate. And for competitive types, 30-35 foot cruising yachts are a popular size for club racing under handicap rating rules.
Premiere of Moscow Boat Show: innovative lifts Presto Marine for jet skis, ribs and tenders. Michael Johansson is sure that good ideas come to many people at the same time. ... Apart from the fact that the lifts were heavy on the stern, the process was labour-intensive and took much more time than they wanted to spend on it, which significantly ...
Whereas racing boats willingly sacrifice pretty much everything in the quest for performance, cruising boats have to be more of a compromise. The Allied Princess - a heavy displacement cruising ketch For a shorthanded crew - as many cruisers are - good handling characteristics are paramount.
The new ferry system will be the water transport system to be operated on the Moskva River in 16 years. Each vessel has a welded aluminium hull, an LOA of 21 metres, a beam of 6.2 metres, a draught of only 1.4 metres, a displacement of 40 tonnes, and capacity for 80 passengers plus two crewmembers. Seating is available for 42 passengers on each ...
This is typical for a cruising sailboat designed more for comfort and stability rather than speed and racing performance. Ballast to Displacement Ratio (B/D): 37.50% With a B/D ratio of 37.50%, the Apla 42 doesn't quite meet the threshold for a very stiff and powerful boat, which is typically 40 or more. However, it still indicates a decent ...
Published Design Ratios The Key Performance Indicators (KPIs). The following analysis of the design ratios gives an indication of the boat's likely sailing characteristics, but see the 'Notes of Caution' below: Sail Area/Displacement Ratio (13.83): This ratio is below 16, indicating that the Westerly Discus 33 is relatively underpowered. It suggests that the boat will not have high performance ...