36 ft all plywood bridgedeck cruising catamaran
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People are right to be concerned about bridgedeck slamming on catamarans. Having said that, it is usually a comfort problem rather than a structural one. Fortunately it is, or should be, a thing of the past.
Early catamarans had low freeboard, partly because of the heavy materials which were all that were available at the time, and also because low freeboard boats always look better. The latter is still true today of course, but people have now got used to seeing high boxy catamarans.
In an attempt to cushion the slamming, many builders, and Prout Catamarans in particular, developed the central nacelle. Prouts took this nacelle to it's extreme and their last designs were more like three hulled catamarans with the nacelle in the water at rest. I took this photo (below) when cruising in Venezuela. A Prout is in the foreground while a conventional high bridgedeck catamaran is in the background.
I have never believed this approach to be a good one. I always say that for offshore sailing one should be able take a conventional inflatable dinghy under the bridgedeck. I sailed the S Atlantic from Capetown to Rio in a Norseman 43. Its bridgedeck was very low (but it looked a very nice boat due to its low freeboard) and it was very uncomfortable living on board. A few years earlier I had sailed from the UK to the Canaries in another low bridgedeck catamaran (again not one of my designs). The slamming was so bad that we were unable to use the saloon table as plates would jump off as we hit every wave.
The Gemini 105 has a notoriously low bridgedeck, in part to keep freeboard hence weight hence costs down. We have been kept awake by the slapping from one that was anchored next to us, while this from one of my customers "I was aboard a 105 last week in Waderick Wells, Bahamas, and was unsure if it was polite to break conversation whilst she slammed while on a protected mooring, or pretend it wasn't happening as I guess their dealers must?"
I took the photo, below, while sailing in the Greek islands. This is a large (over 45ft) catamaran but I do not know what design. Clearly there is not enough bridgedeck clearance!! Yet if you look at the transoms they are still out of the water, so the boat cannot be considered overloaded. A boat like this should have at least 600mm clearance - implying at least 500mm (18in) more freeboard is needed to make it safe and more comfortable. This is not a boat to take to sea, no doubt it was bought because the owners liked the space below and they never took it for a test sail before buying.
Much of this slamming is self inflicted. Imagine two hulls close together pitching into a wave. The water they displace has to go somewhere, and it piles up just as the bridgedeck sails over it. Clearly a wider hull spacing will turn a narrow high peaked mountain of displaced water into a low flat molehill. A wide knuckle and flared hull will also help reduce the size of the induced wave.
The best solution is to start the bridgedeck well back and have it low only where needed. That's why most offshore catamarans have nets or trampolines forward. The boats to avoid if you plan any offshore sailing are those with bridgedecks taken right to the bows.
Furthermore, the water that goes in at the bow also has to come out at the stern, for as the bows pitch out of a wave the sterns will pitch in. So bridgedecks should also be high near the stern. Have a look at the stern of a Prout catamaran, you'll see there is very little space for the bows waves to get out. No wonder they are so noisy to sail - and the waves trying to force their way out must slow the boat down.
I do fit a nacelle on some of my designs, notably on the Gypsy and Romany. I accept the compromises as I wanted standing headroom in a small boat. But I designed these nacelles as footwells so they are as small as possible, (they are only 600mm/2ft wide). I sailed my own Gypsy and Romany thousands of miles and didn't find slamming to be a problem. Mind you, I also had a Veed bottom to the nacelle. Had it been flat then I am sure the slamming would have been noticeable.
So my newer designs (like Transit, Vardo and the powercats) don't have a flat bridgedeck bottom, it's slightly Veed
Of course the smaller the boat the bigger the problem. That's why I don't have any bridgedeck cabin designs with full headroom under 30ft. If you have 6ft headroom on a 30ft boat then scaling it up to 40ft would give you 8ft headroom - more than enough! So a 40ft boat can easily have over 2ft bridgedeck clearance yet still look in proportion
Catamarans have been around, especially in the Pacific, for several thousand years. Early islanders sailed large twin-hulled canoes many thousands of miles, generally from Southeast Asia eastward to discover new island homes.
Modern multihull production started with the catamarans of Hawaiian Rudy Choy in 1947. The first cruising catamaran to circumnavigate was his World Cat in 1965. During the 1960s, Prout and Catalac of Great Britain were also starting to produce catamarans. Catamaran production took off in the late 1970s and early 1980s with French builders Fountaine Pajot, Catana, Lagoon and several others producing catamarans for the charter industry. Gemini also started building boats in the U.S. Soon afterward, South African builder St. Francis got started with a 43-foot cat in about 1990, and now a dozen others in South Africa produce about 30 percent of the world’s cruising cats.
After considerable research looking at a number of boats and more than four years aboard, full-time cruising in Southeast Asia, here are our thoughts on some important features to look for in a bluewater cruising catamaran.
Size vs. cost: As with all boats, as size increases, so does cost. We think a 42- to 48-foot cat makes a great cruising home. Any shorter, and sufficient load-carrying capacity for full-time cruising suffers; longer, and the hull and equipment costs skyrocket.
A stub keel-equipped cat drying out on a beach. |
Bridge deck clearance (BDC): BDC affects the amount of noise in the boat from wave slap, especially while going upwind. We think a catamaran with about 30 inches of clearance is ideal. Increasing the BDC means more windage, which is a negative. Much less than 30 inches, and wave slap becomes a problem in rowdy sea conditions. Longitudinal under-bridge deck fins reduce wave impacts and strengthen the bridge deck. Reducing speed and falling off can also help minimize the problem. Consider how often you actually go close upwind in heavy conditions when cruising versus how much time you spend on other points of sail and in port. The St. Francis 44 has about 24 inches of BDC and it has completed many circumnavigations. However, that does not mean its BDC is ideal.
Load carrying capacity (LCC): Larger boats have more LCC for fuel, water, stores and equipment. Boats with finer hulls are faster than boats with fat hulls, but they will have less LCC. Most full-time cruisers will need at least 5,000 pounds of LCC. When asking this question, make sure you know the hull weight facts and what is included or not. Overloading a cat adversely affects speed, stability and BDC. Beam-to-length (B/L) ratio and stability: For boats in the 42- to 48-foot range, the B/L ratio should be around 50 percent. Less than that will adversely affect stability in heavy beam winds, but larger boats can be okay with slightly less. A higher ratio adversely affects sailing characteristics. Most modern cats are in that range; older cats are somewhat narrower but also have shorter rigs. For more on this important characteristic, search the Internet for “catamaran stability.”
Integrity and quality of build: There is a big difference in build quality across manufacturers of catamarans. Things to look for include builder reputation, hardware quality and strength, use of lightweight construction materials, anodizing vs. painting of aluminum extrusions, interior woodwork finish, exterior design, and equipment quality and installation technique. If water enters older cats made of cored balsa or plywood, there are often maintenance problems. A good construction practice is to make the underwater hulls of solid fiberglass, and the topsides and decks of foam-cored fiberglass. Solid underwater sections are more impact resistant and easier to repair; they also make adding thru-hulls less of a problem. But they do add weight. If enough of the boat is made with lightweight cored fiberglass, the hull will not sink in case of a major collision or capsizing. This is a major catamaran safety feature, as it is always better to be upside-down on the surface than right-side up on the bottom.
A large navigation station and office properly located. |
Engine and power train: Having two engines is a major catamaran benefit. Engine and sail drive location on a lightweight catamaran affects pitching in a seaway, so a central location is better for weight distribution. However, a watertight bulkhead between an aft engine room and main cabins can prevent major flooding in case of shaft or sail drive damage. Engines under bunks or accessible only from aft deck hatches are a problem for routine maintenance and underway repairs, especially in rough weather. Sail drives simplify installations but aren’t as robust as a traditional transmission and shaft installation. From a maintenance standpoint, ensure you can perform routine maintenance easily and remove the engine from the boat if necessary. I consider our amidships engines ideal, but my wife does not agree that the galley is a good place for an engine.
Stub keels vs. daggerboards: Most cruisers prefer stub keels over daggerboards because they allow for drying out on the keel bottoms, can give extra tankage and a double bottom, include a deep bilge, and protect props and rudders from grounding damage. Daggerboards allow slightly higher pointing ability and speed in a narrow, upwind steering angle. However, the trunk and board are hard to clean and paint, the board is vulnerable to grounding and floating debris, and it can get stuck. Most modern catamarans built for cruising feature well-designed stub keels using NACA foil specifications.
Rigging and sails: In order to help prevent losing the mast if a standing rigging component fails, doubled shrouds and headstays are better than singles. We prefer mechanical wire end fittings because in case of a wire failure overseas we would be able to replace it ourselves. There should be sufficient winches to handle all sheets, halyards and reefing lines in an efficient manner. Pay particular attention to how easily reefing is accomplished. Can a light-air sail, a boom vang and preventers be accommodated? Will the mast height allow passage under the 65-foot height restriction for the U.S. inland waterways?
Helm placement: The primary helm station should be well out of the weather, have unobstructed visibility to all four corners of the boat, be quickly accessible from the cockpit, and have all controls and instruments available. Double helm stations, especially those aft on the hull decks and flying bridges, as well as those requiring looking through the saloon windows to see forward, can all be problematic. We think the best option is a single helm station on the forward cockpit bulkhead, well protected from wind and water, and with a good view in all directions — especially forward. Some modern catamaran designs feature a single-level main cabin overhead and cockpit top, which may conflict with the above desirable features.
Chief engineer (author Dave McCampbell) comfortably at work on the port amidships engine. |
Galley location: For those subject to seasickness, galley location can be a personal issue. But for cats less than about 48 feet, locating a large galley with adequate storage in the saloon is a problem. A galley, navigation/office station, dinette table and seating, and three entry/exits are all competing for space there. Further, an adequately sized and located navigation station, galley clutter and light contamination underway are potential problems in “galley up” boats. However, ventilation, crew interaction and seasickness issues are sometimes improved. Ideally, a large refrigerator, pantry and significant galley storage would all be co-located and on the same level with the galley. “Galley up” may be attractive, especially on weeklong charters with guests, but for the other reasons, we prefer the “galley down” arrangement for full-time cruising.
Navigation station: When full-time cruising, the navigation station becomes important for navigating, communicating and office use. Additionally, the circuit breaker panel, most electronics and battery/charging controls should be located there. Ideally, it would be positioned forward in the saloon with a comfortable seat and a good view forward.
Ground tackle: As one of the more heavily loaded systems on a cruising boat, high strength and no weak links are important for all ground tackle equipment. Look for double anchor rollers, strong bridle attachment fittings and good ground tackle storage arrangements. One of the better bridle attachment points is at the bow crossbeam to hull fittings. These should be exceptionally strong, and many boats have specially designed attachment fittings here. Ensure bridle-to-chain attachment fittings are full strength, removal can be done quickly, muddy chain can be washed effectively and that the chain locker is deep enough to minimize chain castles. The windlass should be robust enough to handle the boat’s ground tackle in at least gale conditions. Choose your anchors carefully; large scoops, like the Spade or Rocna, perform much better than older designs.
Decks: Uncluttered and relatively flat decks are preferred for safety at sea. Nonskid needs to be aggressive enough to ensure no crew slippage when wet. Fittings should be very robust and of quality construction. At least six large cleats should be very strongly mounted with large backing plates to spread out heavy loads. Many modern cats have little or no exposed teak — a feature I appreciate.
Rain-catching hardtop with solar panels and boom crutch. |
Bows and rudders: Bows and rudders should be strongly reinforced on their leading edges and designed so as not to catch lines and logs underway. Modern vertical and reverse stems, as well as spade rudders, have more of a problem with this than traditional skeg-hung rudders and bow shapes. Both keels and rudders should be designed to NACA specifications in order to perform efficiently.
Liquid capacities: For full-time cruising overseas, we think an onboard fuel capacity for a 1,200-nm range on one engine and about three weeks of water are ideal. At our average use of about seven gallons per day, about 150 gallons gives us more than 20 days of water. That is enough for many long ocean passages if there is no rain and the watermaker quits. Many modern charter cats have a large water capacity but a small one for fuel.
Watermaker: A large-capacity (approximately 40 gallons per hour) watermaker makes good sense in order to reduce the unit’s run time and the weight of stored fresh water aboard. Simple mechanically driven units are far less expensive, are less of a maintenance problem and can have higher capacity than 12-volt electrical units. We almost always are able to run ours when otherwise underway, so there is little need to run it at anchor — and most of the time we can collect sufficient rainwater anyway.
Refrigeration: As full-time cruisers overseas, we prefer a separate front-loading refrigerator for its convenient and quick interior access. However, the freezer needs to be top loading to provide good thermal efficiency. Capacities of up to 10 cubic feet for the refrigerator and 4 cubic feet for the freezer will provide good long-term storage. These are manageable for electrical energy usage, provided good system design and proper insulation values are used. However, many refrigeration boxes are deficient in insulation. The closer the refrigerator is to the galley the better from the cook’s point of view.
An example of uncluttered flat decks and no teak needing upkeep! |
Cockpit covers: A well-designed solid cockpit cover should be able to prevent rain from entering the cockpit through the use of removable front and side curtains, facilitate access to the mainsail and the back of the boom, allow for mounting multiple solar panels, and be able to collect a significant amount of fresh rain water. Careful design will prevent water from entering the cockpit during rains while still allowing some ventilation. Ensure the edges won’t drip on the cockpit seats or instruments. Lightweight construction is a plus.
Dinghy davits: Some dinghy davits are incorporated into an arch or tubular support for the cockpit top. These need to be very strongly constructed because the dinghy usually lives there at sea. It should allow hoisting of the dinghy well above the water to help prevent theft and wave slap.
Saloon windows and doors: Extra strength and careful design are required to prevent large breaking waves from flooding the boat and easy entry by an intruder. Thick polycarbonate/Lexan or safety glass is best; acrylic/Plexiglas should not be used. Inspect the window mountings and door hardware carefully for adequate strength and watertightness. Consider main cabin window designs that limit heat entry from the midday sun.
Ventilation: Multiple opening hatches and ports should ventilate every space, especially the saloon, galley, sleeping quarters and heads. We have 14 hatches, six ports and two escape hatches — all opening. Escape hatches provide excellent ventilation, should be large enough for you to pass through, and should be located at least 18 inches above the waterline to prevent flooding while open at anchor. All should be of quality manufacture with tight replaceable seals. Provisions to prevent intruder entry are a plus. Consider how well ventilated the cockpit is in light wind conditions.
Crash bulkheads: Modern catamarans have crash bulkheads located forward and aft in each hull to prevent collision flooding. They should be well sealed from adjacent spaces and have door lips well above the waterline. Obviously, these are not places for heavy gear. Installation of large holding tanks, which are usually empty at sea, can provide a double bottom in the bow.
Good escape hatch location above the DWL. |
There is plenty here to consider before purchasing a cruising catamaran. Many modern cats are built for the lucrative charter trade and have features that may not work well — like minimal fuel storage capacity — for full-time ocean cruising. Some of these can be corrected or improved, some cannot. There is much good information on the Internet, but be suspicious of dealer hype. Ask specific questions and request proof of anything that doesn’t seem right. Make a list of what to look for before going aboard a potential purchase. Although most cruisers spend 90 percent of their time in port, due consideration should also be given to features that enhance safety and comfort at sea. Most catamarans are optimized for tropics cruising and are probably not the best choices for high-latitude voyaging.
There is no perfect catamaran with all the features you will want, so be prepared to compromise somewhat. Photos and more detail are available on our website below, under a slide presentation titled “ Evaluating Modern Catamarans .”
Dave McCampbell is a retired U.S. Navy diving and salvage officer with over 40 years’ cruising and eight sailboats’ worth of maintenance experience. He and his wife, Sherry, have recently cruised the eastern portion of Southeast Asia, including the Philippines, Raja Ampat, Papua New Guinea and the Solomons. Earlier, they spent eight years slowly crossing the Pacific. After 19 years aboard their CSY 44 monohull, they bought a St. Francis 44 Mk II catamaran in 2015.
Open for discussions and opinions (1) Interested in comments from Catamaran owners re Bridge deck clearance. I have heard reports about low bridge deck clearance causes Slamming and pounding of significant proportions when sailing to windward. Comments please. (2) Some designs have .500m clearance others .700m and I notice the latest designs on some are rising to .950m and 1.2m bridge deck clearance. Comments please. (3) I have noticed quite a few catamarans stay in port while Monohulls make passage to their next port. When asked why they are staying in port I,m told waiting for for less wind and a better wind angle. Supposedly this has something to do with Slamming and pounding? Comments please. ( 4) Galley preference. Main bridge deck or hull. As a interested cook and have cooked on numerous vessels I ponder the merits in having the galley within the bridge deck. Re heat transfer- Condensation- Moisture- the heat generated from the galley causing condensation on the ceiling, moisture gathering in drapes, upholstery plus smells and vapours, books in library pages being affected and absorbing the moisture. As usually with most modern designs the chart table and electricall main board and electronics are also positioned in main saloon - bridge deck, I wonder the wisdom re this. I would have thought the galley in the hull would be preferable with higher head room - hatches and extractions fans and more ventilation - thus removal and moisture control would be more efficient, plus providing a larger lounge area in the main saloon. After all the kitchen in most homes is not in the lounge. Plus normally in the tropics if one does not have air conditioning one gathers with chilled drinks in the cockpit area with sea breezes and a view and possibly to be a nosey parker while the cook cooks. Comments please. Below are some hyperlinks to a new design with increased bridge deck clearance. How ever I,m would have thought for offshore passage and in moderate to heavy seas a clearance around about 1.6m to 1.8m would be needed to avoid constant bridge deck slamming when going to windward or even slightly cracked sheets. Comments please. http://www.schionningdesigns.com.au/1700c http://www.schionningdesigns.com.au/gforce-1800 http://www.schionningdesigns.com.au/1200 Thanks in anticipation. http://homepages.ihug.co.nz/~philclarke/flag%20ETIQUETTE.htm -------------------------------------------------------------------------------- __________________ "Let the sun shine, let the rain cease, let the lakes and rivers run dry so 2012AD, 2013AD & 2014AD are good vintage years and gold, elite gold medal winning years for N.Z.wines" Now!! :chaser :chaser
Why wouldn't bridgedeck clearance be a function of size?
It's not a function of size, just look at some of the condomarans with 40' loa and 10 inches of clearance. I seem to recall reading somewhere that the absolute minimum bridgedeck clearance you want is 19", from the lowest point of the bridgedeck to the water. This includes any Nacelle (spelling?) hanging down from the bridgedeck. If you really want to understand this issue go to boatdesign.net and do a forum search, there is lots and lots of data, much of it from NA's and designers (richard woods posts there frequently) and you will get a fuller understanding of the issue.
peterchech said: ...If you really want to understand this issue go to boatdesign.net and do a forum search, there is lots and lots of data, much of it from NA's and designers (richard woods posts there frequently) and you will get a fuller understanding of the issue. Click to expand...
I don't know enough about the bridge deck issue to comment on specific heights but insufficient height is a major problem from what I do know. Regarding the interior, I'd favour a downstairs galley. My biggest complaint about catamaran layouts is the restricted seating space in the saloon where much space is taken up by the galley and/or nav station. Must say I do like the layout of the Schoening 1320 though I know nothing about the boat itself. The 1700 is for my money absurdly large, but then I only think about space for a couple plus very occasional guests. The way I figure the galley is this. Down below gets it out of the way with one major drawback being heat in warmer climes. For me that is negated by the fact that in summer we always cook outside and with a cats cockpit even preparation outside is simple. Others might say that the galley in the saloon allows more interaction twixt the cook and the crew. Fair enough I guess but I still don't think that outweighs the other issues.
tdw said: I don't know enough about the bridge deck issue to comment on specific heights but insufficient height is a major problem from what I do know. {Thanks} Regarding the interior, I'd favour a downstairs galley. My biggest complaint about catamaran layouts is the restricted seating space in the saloon where much space is taken up by the galley and/or nav station. [Agree my thoughts exactly] Must say I do like the layout of the Schoening 1320 though I know nothing about the boat itself. The 1700 is for my money absurdly large ,[ I think you need it if your doing offshore passages and have extra crew to help with watches so one does not get tired and irritable, and depending on your age.] but then I only think about space for a couple plus very occasional guests. The way I figure the galley is this. Down below gets it out of the way with one major drawback being heat in warmer climes. For me that is negated by the fact that in summer we always cook outside and with a cats cockpit even preparation outside is simple. [ Most boats these days have a BBQ,s hanging from the stantions or pushpit.] Others might say that the galley in the saloon allows more interaction twixt the cook and the crew. Fair enough I guess but I still don't think that outweighs the other issues.[/QUOTE ][ Good point agree.] Oceancruiser. Click to expand...
Most any catamaran will pound in certain sea states. If you're looking to eliminate pounding, buy a monomoran. I dont have rules of measurement that I can help you with but common sense should prevail. If the bridge deck clearance looks low, its going to pound more that one that does not look low. Galley down works for us. Its open and inclusive of folks working in the galley with those living in the saloon. When I was chartering catamarans for vacation sailing, I prefered galley up. Living aboard, galley up is a deal breaker. I dont want to cook in my living room. We comfortably seat 6. 8 is a push, but doable for dinner.
My comments about Bridge-deck clearance comes from the lips of designer comments I have read. They also come from a Cat sailor who owns a Catana 381 that has 2' 6" clearance and it does not slam, I know because I sail it like the Tornado Olimpis Cat I used to race. I am just about to Launch my Website which tell you what Cat NOT TO BUY, depending on your requirements of course, if you want a Condo, have one, if you want to sail sideways have Skegs, if you like Hobby Horsing or slow Cats there are thousands out there, mostly from the Production boat department. Watch out over the next few months when I launch my Web site, type in Catamaran and you will find me. As for the topic in question: there are 6 main things you need in a good Cat design and one of them is NOT low bridge-deck clearance. Most Cats have none of the 6 requirements, they either have Fat hulls, Skegs, reduced Sail area, bad Bridge-deck clearance, too heavy and wide open slot and they all sail like floating Homes. I have 200 Cat listed on my database all with designer calculations saying which one is capable of sailing well, assuming 'well' is whats wanted. I'm looking at 6 Cats I might buy in the 45-48' range, they must have at least 4 to 5 of the 6 design requirements listed above, if they don't I move on. I have been told my requirement is very high and most Cats don't have what I want, that is true. I can find only 10 Cats that come into my top ten for sailing ability and the all have High Bridge-deck clearance. I sail at 35deg to wind beating of Monohulls who try to get near me, to windward of course, I sail higher than them. I don't want to give too much away in Loo of my Web site Launch. There is a small fee but it's worth it. Regards Barry Parkinson Ex Tornado helm and Catana 381 owner.
Quote: I can find only 10 Cats that come into my top ten for sailing ability and the all have High Bridge-deck clearance Interested to see your top 10 sailling ability Cats and the hights of there respective bridge deck clearance. I also notice from the Catana Web site there new design has reversed bows and they have increased there bridge deck clearance. Not to dis-similar from the design above hyperlinked. Interesting !! Be interesting to see how yourwebsite goes-- Fee/ pay by credit card. I don't think so
I am interested to see those 6 requirements as well. The problem with catamarans is that in order to retain the excellent performance that multis are capable of, the catamaran has to have certain features such as narrow hulls, low windage (ie minimal bridgedeck), daggerboards, etc. These very features mean that to have comfortable accomodations the cat has to be very big. Otherwise something has to give. And once you get big, most boat owners get priced out. You need bucku bucks to buy a 50' catamaran, and even more to find a place to keep it. So, as with everything in life, compromise is required. Some compromise better than others, but since the charter market seems to drive catamaran sales, the accomodations are favored over the performance/safety in most commercial designs. I personally am a sailor, not a on the hook cruiser or live aboard, so even when cruising I can't tolerate a poorly sailing vessel and would never get a condo maran. But others, particularly those who charter, may have different priorities. For this reason I think a trimaran is the way to go if sailing performance is what you want. Most trimarans are not built for anything but true sailing ability. Those who buy a tri generally want to go fast and have fun. The arms fold up so you can find a spot in a marina. The accomodations are more like a smaller loa monohull, and way less comfortable than a cat, but that is the kind of compromise I am willing to make personally. If you want that standing headroom bridgedeck, the compromise is high windage and poor bridgedeck clearance, at least until you get to a really big cat IMHO. BTW, "The Cruising Multihull", by Chris White, is an excellent book on this subject, and is available as a pdf download or else used on amazon for $10 when I bought it. It's a wonderful book and you should def read it before buying any multihull, it addresses all these issues and compromises from the standpoint of a designer and full time cruiser. Great read too, not overly technical and very enjoyable.
peterchech said: ... For this reason I think a trimaran is the way to go if sailing performance is what you want. Most trimarans are not built for anything but true sailing ability. Those who buy a tri generally want to go fast and have fun. The arms fold up so you can find a spot in a marina. The accomodations are more like a smaller loa monohull, and way less comfortable than a cat, but that is the kind of compromise I am willing to make personally. If you want that standing headroom bridgedeck, the compromise is high windage and poor bridgedeck clearance, at least until you get to a really big cat IMHO. .... Click to expand...
Hi petercheck, I have read your thread and I bet you are interested in my top ten Cats and the 6 requirements for quick Cat sailing, thats why I am launching My 'What Cat not to buy and why' Lots of Cat buyers are sold up the river by Brokers who say 'have a nice day' but don't mean it. I got fed up listening to the garbage Brokers talk over the past 5 years, and that is the main reason for Launching my Website. The other one is because a Great Cat in the West Palm Beach in the Cracker Boy Yard, has been butchered by the Loving owners, I wanted to but it until I put it through my Spreadsheet to get a 'Bruce number' (Power to weight ratio) and it sucked. I asked the Architect what was in the original design and found they had cut the Dagger-boards in half and poss the rudders as well, loaded the weight up from 10 Ton to 12 Ton, reduced the sail area and generally messed up a very good Cat that cannot sail well anymore. I wanted to expose people and Brokers like this to the budding Cat sailor who has a lot to learn about Cats and end up buying things that float, thats why it is called a boat, but it does not sail well because the production Cats do not have any of the 6 requirements I talk of. I could talk for a week on Cat design but this is not the place to do it. All I want to do is give potential Cat buyers somewhere they can go to ask questions about potential Cat purchases they might make, before they make a mistake, like so many Cat owners who are disappointed with what they bought, for one reason or another. I know the answers, with 200 Cats on my database I should do, and soon I will be able to let the Cat buying public know what Catamaran/Multihull not to buy. Give me 2 weeks and I should be Online with my Website but, there is a small fee, but you said you did not thinks so, I take it you don't thing buyers will pay $50 to find out what I know, we will see. It's been great talking, no doubt we will do more. I am looking forward to helping cat buyers choose the correct boat before they buy. Best regards Barry Parkinson
Bazcatana said: Hi petercheck, I have read your thread and I bet you are interested in my top ten Cats and the 6 requirements for quick Cat sailing, thats why I am launching My 'What Cat not to buy and why I asked the Architect what was in the original design and found they had cut the Dagger-boards in half and poss the rudders as well, loaded the weight up from 10 Ton to 12 Ton, reduced the sail area and generally messed up a very good Cat that cannot sail well anymore. I wanted to expose people and Brokers like this to the budding Cat sailor who has a lot to learn about Cats and end up buying things that float, thats why it is called a boat, but it does not sail well because the production Cats do not have any of the 6 requirements I talk of. . All I want to do is give potential Cat buyers somewhere they can go to ask questions about potential Cat purchases they might make, before they make a mistake, like so many Cat owners who are disappointed with what they bought, for one reason or another. Give me 2 weeks and I should be Online with my Website but, there is a small fee, but you said you did not thinks so , [ No that was me] I take it you don't thing buyers will pay $50 to find out what I know, we will see. I am looking forward to helping cat buyers choose the correct boat before they buy. Best regards Barry Parkinson Click to expand...
giving someone $50 for the same 2 cents you can find elsewhere on the internet seems a tad unrealistic to me, but I wish you good luck none the less!
Hi again petercheck, CREDIBILITY was my first requirement 5 years ago when this all got going. I extracted the design mathematics for my 'Power to Weight Ratio' spreadsheet (Bruce number) from the design pages of a top quality Catamaran designer in Australia, there on the web for all to see. I built my Spreadsheet using this information that they use when designing Cats/Multihulls to establish what works and what does not. I am not preaching MY thoughts and feelings, I am preaching THEIR design knowledge, not mine. I am not presumptuous enough to think anybody is interested in my views, that is just like another Blogger saying what he thinks, and whats the value in that, it's not credible. Your right, nobody knows who I am, I could be any old Blogger voicing his opinion, it will take time for my reputation to filter through but, I can tell you it stops the Brokers dead in their tracks, when you ask the questions I ask and request the data I require for my 'Bruce number' calculation. The method of payment I will use is via PayPal which I am told is secure, I don't see the Credit Card details, only the payment. Then I send my report to the potential Catamaran/Multihull buyer, telling them what NOT TO BUY if there is something that shows up in my calculations, and you can't get that for 2 cents on the Web anywhere. I have met hundreds of new Cat owners who are disappointed with their purchase. They think all Cats are fast, it's a misconception that many fall into, blinded by Broker and Press garbage they talk and publish. Try me out for FREE, send me some details of a Catamaran you would like to buy, send it to my [email protected] Email and I will send you a Form to fill in. Return that to me and I will tell you what I think. Don't play around, try and be serious, I am trying to HELP buyers choose a Cat that they will be happy with, I'm not selling anything, just helping buyers find the ideal Multihull. Regards Barry Parkinson
Bazcatana said: I have met hundreds of new Cat owners who are disappointed with their purchase. They think all Cats are fast, it's a misconception that many fall into, blinded by Broker and Press garbage they talk and publish. Try me out for FREE, send me some details of a Catamaran you would like to buy. Regards Barry Parkinson Click to expand...
Try me out for FREE, send me some details of a Catamaran you would like to buy, send it to my [email protected] Email and I will send you a Form to fill in. Return that to me and I will tell you what I think. Don't play around, try and be serious, I am trying to HELP buyers choose a Cat that they will be happy with, I'm not selling anything, just helping buyers find the ideal Multihull. Regards Barry Parkinson[/QUOTE] You will have 11 after viewing this Cat Young Yacht Design Be interested to know if it passes you scrutiny.
Where is a site to get complete specs on various cat designs ?
Where is a site to get complete specs on various cat designs ? Click to expand...
Thanks.
I have paid a great deal of attention to the cats cruising the Antilles over the last 3 years. 90% of them are just floating condos, without the ability to go to windward or down wind well, unless the have down wind sails specifically built. Few have 1/2 enough clearance under the "bridge deck" to be comfortable in a 3' chop, let alone an average tradewind day down here. Most are rigged so you can't let the main out far enough to comfortably sail on a broad reach, and almost every single one we see sailing interisland has at least one engine on, even on a breezy tradewind day. Most have a very sharp, jerky motion which must be horribly uncomfortable under way or in a rolly anchorage. There are a few designs which have dagger boards and enough freeboard to quite possibly sail decently, but they still don't seem to have the speed to make up for the difference in the pointing ability of a good monohull. As for trimarans, there are good ones and bad ones, like any other type of boat. If we exclude racing tris and concentrate on cruising tris, none have the speed or agility to sail safely through pirate filled waters (pirates usually operate on calmer days, certainly not in the gale force winds it would take to get away). Unless you have several very, very experienced crew on board a tri at sea, most cruisers would not be able to maintain the 16 to 25 knots it would take to out run a storm. It certainly would not be prudent to put her on autopilot or a windvane at those speeds, IMO. I do think a well designed cruising tri is a far superior sailing vessel to any cat out there, and a much more stable platform from which to set sails. I sailed a Brown Searunner 37' from Pago Pago to the VI, crossing 1/2 the Pacific, the Indian Ocean, the Red Sea, the Med and Atlantic. I sailed her out of a hurricane in the Indian Ocean, 1200 miles hard to weather up the Red Sea and through many a gale without any problems. Inside the reefs of New Caledonia, I had her up to nearly 25 knots, but that was flat water in perfect conditions. At sea, I would never let the mindless machine (the windvane) sail the boat above 10 knots, period. Best of all, I could sail in light air, when every monohull and cat was motoring, usually making around 5 knots. It was the most wonderful cruising boat I've ever sailed, but they must be kept very, very light. Pretty much bare bones sailing with few mod cons, which is why I've gone back to a monohull in my old age. If you want to SAIL, then you are better off choosing a monohull or trimaran. If you are just looking to move to a mobile house on the water, then the majority of the cats out there are the perfect choice. Every boat is a compromise.
Strange. I sailed on a Chris White 56 ft tri ocean going . No problems reaching 12 knts boat speed 12 knts slight cracked sheets, wind speed. 18 knts, boat speed at 19 knts wind speed. At 12 knots forward cabin berths uncomfortable to sleep and at 16 knts had to be strapped on. Although no lee clothes or straps where standard equipment. I rightly or wrongly put this due to the chine design main hull near waterline bow to mid ships. We either slowed the boat or move aft. Had a turbo charge engine and at cruising revs 66 2/3 12 knts at full revs 16 knts. At 6 knts wind speed achieved 6 knts boat speed. Most watches where single person watches and usually on auto pilot. So I guess if people are going to sail through pirate territory a chris whit tri should give some self confidence and added safety as a worth while consideration. Thanks for your comments.
Well, there's the 'rub', so to speak. Unless you've bought yourself a new America's Cup class catamaran, a catamaran sailor isn't going to be arguing his boat goes to weather better than a monohull. But the question is ... is that how you define the boat you want own? How high she points? That doesn't even make my top ten list. Finding a boat that my lady can't wait to sail on rates a lot higher, as without her, I'm not going anywhere. Comfort while cruising is high on he list as I just can't picture her standing on a bulkhead for days at a time. And whether you sail one hull or two, sailing (relatively)small FRP boats is all about picking a weather window. I'm at that stage of life where I know how to pick my battles... and boats ...like life ... are all about compromises, right?
With a cat it's not so much how high you can point but VMG. The cat may sail 5 or so degrees more of the wind but will reach their destination quicker. True, the trend nowadays is for the condo cat, but there are still some performance oriented cats still around. It's been my experience that we usually sail past the monos that are motor sailing. The cats must have some appeal as a lot of the experienced mono hullers are transitioning toward cats. Not everybody's cup of tea though.
Thanks, but I'm really looking for owners with Cats to confirm slamming re their owned vessels and the designs bridge deck numbers and owners that have sailed to windward with 36 knts on the nose wind with no slamming and the bridge deck clearance numbers. On a long passages there is always on the wind part sailing even to enter port on most occasions. VMG is important unless you want to change your port on entry. I have known mono hull sailors vessels to do so to the protests of the crew. His argument he did not like to sail on the wind. The crew argued "you guaranteed the place as a stop over and we accepted your vessel as crew and are paying $30 per day other wise we would have chosen another vessel". As for sailing not so high I would respectfully disagree. Some years ago a racing cat design By David barker and the fastest cat around at the time, Auckland to Suva just under three days 1300 nms did the numbers. Had a girl friend at AMP computer room feed all the points on sail from hard on the wind to reaching to determine the increased speed he would have to achieve to be ahead. The computer print he stated stretched the entire width of Sydney harbour. He spent days trying and never achieved any of the speeds that where required according to the computer results. Thanks for you expanding comments. Kind Wishes. http://homepages.ihug.co.nz/~philclarke/SAILING%20MECCA.htm
Yes, someone is going to beat into that. Well, it was 30kt, not 36. It was a Gulf crossing/delivery, and we didn't have the luxury of heading off. Boat is a 1992 Catana 40S. In this vid, we are motorsailing. By this time the wind had cocked slightly east of exactly, directly, in front of us, so we did hang some laundry, but for probably 8 or more hours before the wind had been directly on the nose (frontal passage) and we just doused and engined into it. Despite the high bridgedeck, and believe me I don't load my boats down, she did some banging, although I believe had the wavelengths been longer, banging might have been less. The Gulf of Mexico has a surprisingly short wave pattern, short and steep. Apparently TropicCat is quite lucky to be able to make the choices he apparently does. As for the rest of us, sometimes you just gotta get there.
Multihullgirl said: Yes, someone is going to beat into that. Well, it was 30kt, not 36. It was a Gulf crossing/delivery, and we didn't have the luxury of heading off. Boat is a 1992 Catana 40S. In this vid, we are motorsailing. By this time the wind had cocked slightly east of exactly, directly, in front of us, so we did hang some laundry, but for probably 8 or more hours before the wind had been directly on the nose (frontal passage) and we just doused and engined into it. Despite the high bridgedeck, and believe me I don't load my boats down, she did some banging, although I believe had the wavelengths been longer, banging might have been less. The Gulf of Mexico has a surprisingly short wave pattern, short and steep. Apparently TropicCat is quite lucky to be able to make the choices he apparently does. As for the rest of us, sometimes you just gotta get there. Click to expand...
If you don't have speed you have nothing let alone safety. Firmly believe boats should have enough speed to sail around a cyclone or a storm or get to port before the storm arrives at your sailing course / path. NOT ONE FOR WAITING FOR 42 DAYS OR MORE FOR A WINDOW TO SUIT A SLOW CROSSING. berth age fees for multihull vessels are far to expensive for long port stays and one seems to spend the time when waiting for a weather window partying, which is also expensive during long stays at ports. WITH RESPECT AGAIN, WHEN I'm IN A HURRY I catch a commercial airline jet.
Sailed a 44' aluminium cat to India from Thailand. Sometimes you couldn't put your coffee cup on the table for the slamming. Got real tiring. Condensation was bad and ventilation at sea minimal or wet. Great on the hook for entertaining and lots of storage space on board as long as you don't put anything in it. Saw another cat (sleek Italian job) with a bloody big gen set in one hull and a washer/dryer/freezer in the other. Neither of these vessels sailed worth a damm. And didn't even have the classic good looks and comfort of my homebuilt gaffer.
piclarke said: After all the kitchen in most homes is not in the lounge. Click to expand...
Thanks for your comments. I do not like cleaning and the kitchen is my domain also for hygiene reasons, so parting at the kitchen is a no no. Use the Cockpit BBQ when parting. I have and always try to party at the cockpit area as the guests quite correctly are not asked to clean the mess they leave when parting. Accordingly the bucket and lanyard or pressure hose does the trick especially when some can't hold their drink and vomit. Best regards.
I've said before: I'd just as soon not have the burny bits in the floaty bits. Bridgedeck galley for me.
I don't know how high my bridge is, and to be honest, it really doesn't matter. I may stand corrected here, but I'd bet that there is no such thing as a cat which doesn't suffer some slamming, if the conditions are right for her to slam. Of course, the lower the bridge, the more often that slamming will occur. It's fairly obvious which cats are low and which aren't, just by looking. A few cm one way or the other ain't going to tell any tales. BTW, the answers you seek are already discussed ad nauseum online, and there are plenty of books on the subject. If you find it painful to Google, I find it painful to repeat freely available information.
quote=Multihullgirl;2300938]I don't know how high my bridge is, and to be honest, it really doesn't matter. I may stand corrected here, but I'd bet that there is no such thing as a cat which doesn't suffer some slamming, if the conditions are right for her to slam. Of course, the lower the bridge, the more often that slamming will occur. It's fairly obvious which cats are low and which aren't, just by looking. A few cm one way or the other ain't going to tell any tales. BTW, the answers you seek are already discussed ad nauseum online, and there are plenty of books on the subject. If you find it painful to Google, I find it painful to repeat freely available information.[/quote] Thanks for your comments. A proven and now accepted as the best and fastest cruising catamaran designer states his Catamarans do not slam. His designs have bridge decks clearance between .950 and 1.2 meters and he states bridge deck clearance does matter and I attend to agree. The numbers have not been discussed ad nausea online as can been seen from the posts so far. Even your posts do not quote the numbers. Been to the manufacturer Catana website which does not quote a 40s model and the length vessels that are their models, custom built vessels specifications bridge deck clearance are not mentioned on all the designs. With respect I'm actually trying to find a Catamaran owner with bridge deck clearance .950 or more that can state / verify his vessel does not slam going to windward sailing or motoring with heavy seas or confused seas / or heavy confused harbour waters. Is this not what forums are for. Trying to establish what the manufactures claim to be correct or incorrect. http://homepages.ihug.co.nz/~philclarke/americascupstats.html
piclarke said: With respect I'm actually trying to find a Catamaran owner with bridge deck clearance .950 or more that can state / verify his vessel does not slam going to windward sailing or motoring with heavy seas or confused seas / or heavy confused harbour waters. Is this not what forums are for. Trying to establish what the manufactures claim to be correct or incorrect.... Click to expand...
Gavin le Sueur, MULTIHULL SEAMANSHIP Rudy Choy, CATAMARANS OFFSHORE Chris White, THE CRUISING MULTIHULL Derek Harvey, MULTIHULLS FOR CRUISING AND RACING Rob James, MULTIHULLS OFFSHORE that should get you started. BTW, manufacturers don't really lie outright, but they stretch the hell out of the truth... I reread my post. I'll clarify my point: when I said 'it doesn't matter,' I mean, the numbers don't matter. I can see the difference between a high and a low bridge cat. That isn't the only consideration for a seagoing cat. I believe there is no such thing as a cat with a high enough bridge that will never, ever slam. I believe it is best to get a high-bridgedeck cat to avoid slamming, but I find it hard to believe that there is a cat that will not find itself doing some slamming at some point. I went to the Miami show and looked at the new cat designs, and with one exception, I'd be damned if I'd go to sea in them, frankly. And the bridgedecks weren't the worst problem these boats had IMO.
QUOTE and with one exception, I'd be damned if I'd go to sea in them, Care to name the design and provide a hyperlink to the designer. Interested as to what you would choose to sail across oceans. Plus other members would also be interested I presume. I look forward to your reply. Worldwide Best Yachting surf beach harbour entrances and ocean sea conditions with Web Cams reports and weather swell reports marine data resource links site business accommdation directory guide lists base including new zealand australia south pacif
What Makes a Good Catamaran?
As we (Stephen and Estelle) self-isolate during this pandemic aboard Zuri, our Bali 5.4, we thought we would share some insights about important features you should think about when buying a catamaran. We started out with 5 then at the end, Stephen threw in another 3. What are your thoughts? What are important features on a catamaran. Let us know below in the comment section.
Like all marine vessels, certain characteristics make some catamarans better than others. You will not find a perfect catamaran because no boat is perfect. Compromise is always required. But with forethought about how you will utilize your multihull, and matching your requirements to high quality design, you can get pretty close to your “dream” catamaran.
Crucial attributes to consider for a cruising catamaran are:
We will explore each of these catamaran characteristics, and how they affect performance, comfort, and, ultimately, safety.
Early catamaran designs were heavy by today’s standards. The multihulls were designed with a narrow beam, high freeboard, and inefficient underwater design. They were prone to hobby horsing and pitching. Today, with the technological advancements of lighter, stronger composite materials, catamarans performance has greatly improved.
In the last 20 years or so, boat builders have painstakingly studied and resolved the issues affecting catamarans, effectively increasing their seaworthiness by leaps and bounds. Constant reform and transformation of even the basic tenets of catamaran design continue today as is evident in the radical catamaran designs in the 2013 America’s Cup Challenge. (The foiling Gunboat G4 designs spring to mind). In fact, many of the problems of the older multihull designs have been eliminated altogether.
The new generation of cruising catamarans offers exciting, fun sailing vessels with great livability, space, comfort, and safety. This was made possible, in no small part, by the early multihull pioneers.
WEIGHT: Unlike the monohull design that can carry weight without much loss of performance, an overloaded catamaran rapidly loses performance and, eventually, safety. In order to counter this, multihull manufacturers are continually looking for ways to reduce construction weight to increase the potential payload capacity while retaining optimal performance.To select a light catamaran, look for hulls with cored construction and interiors built with lightweight materials. Lighter construction enables catamarans to carry more weight and perform faster, so this characteristic is very important when selecting a cruising catamaran.
Monohulls can heel and spill wind when the sails are overpowered. But a catamaran’s only available response to pressure of a wind gust is to accelerate. So the boat has to be very strong to hold together. Cored construction makes the catamaran strong and very stiff. Stiffness gives a catamaran good performance.
Consider that the catamaran’s hulls are actually two boats joined together by a bridge deck. These “boats” are constantly fighting each other and trying to go in their own direction. The boat structure must be strong enough to counter this and, at the same time, deal with the downforce of the mast in the center of the bridge deck. The catamaran performs an amazing feat contending with all the opposing forces inherent in the multihull design. For that reason, it is critical to ensure the design and manufacturer are reputable with a track record to demonstrate structural integrity.
STABILITY: Unlike monohulls that rely on a heavy lead keel to keep it upright, a catamaran relies on the beam of the boat and the buoyancy of the hulls for stability. Typically cruising catamarans will have a beam to length ratio of roughly 50%. So a 45-ft long catamaran will be about 22-ft wide, providing a very stable platform. Good stability in a catamaran is when the righting forces and healing forces are in balance. So if the righting moment is greater than the capsizing moment, the boat stays upright. When the capsizing moment becomes bigger than the righting moment due to an increase in wind, the boat starts to capsize. <
This diagram and article by James Wharram, king of “self-build” catamarans, offer valuable insight into catamaran stability. Also, read this article by Shuttleworth “ Design Considerations for Seaworthiness “.
Bridge deck clearance is a key factor in predicting the slamming level of a catamaran design. A higher clearance produces less slamming. My rule of thumb is; 4% of the overall length is low, 5% is acceptable, and 6% is good.
When it comes to slamming, another important factor is weight. If the boat is heavy due to construction or payload, it will tend to go into a wave. This slams the chest of the boat into the wave. A lighter boat with more buoyancy will rise on the wave reducing slamming substantially. “ The Space Between ” by Sackville Currie, explains in detail the different options, problems, and compromises.
Catamarans with dagger boards are able to point much better than catamarans with keels. The claim is that a catamaran with dagger boards is safer because if the boards are up and the boat gets sideways on a wave, it will skid down the wave sideways. Dagger board proponents believe a keel trips the boat as it tries to navigate down the side of a wave causing capsize.
I can only speak from personal experience. I was caught sideways on a 20-foot wave a few days out of Cape Town on a 40ft catamaran with keels. The boat was hit by successive three waves before we could get it back on track. The boat skidded down the waves and there was no capsize, but it took some nifty maneuvering at the helm. My personal belief is that both types are safe and acceptable provided they are operated correctly.
Older designs often have decks with two levels from the coach roof windows to the gunnels which form a side deck with a trip hazard. Most modern catamaran deck designs are now one flat surface being wide enough to walk unhindered from the cockpit to the mast.
The cockpit and the saloon should be on one level with no step down into the saloon, if possible. Modern designs have achieved this and it really makes a big difference for ease of movement and safety while at sea.
The steps on the stern should be wide and easy to climb with a reasonable angle. If the steps are too steep or narrow, they become a hazard and lose space for recreation. The stern should be easily accessible from the dinghy.
Visibility from the helm is also very important. All round visibility while underway, maneuvering, or docking is key to safety of your boat and others’ property and life. When standing at the helm, you should be able to see both bows or, at the very least, the pulpits. The center of the crossbeam where the anchor is handled from should be visible as well as both sterns for when you dock “stern to”. If all these stations are not visible while standing at the helm where the engine controls are, you may encounter problems because of blind spots.
Modern catamaran designs are much more advanced than the early models that were slower, heavier, and underpowered. Problems like hobby horsing, burying the bows, and underpowered rigs have been largely eliminated.
Even though composite construction technology gives a huge advantage in lighter materials and sleeker designs, no one design element or piece of high tech gear should dominate the vessel to the detriment of others. With some compromise, a good naval architect can design a vessel pleasing to most people and the result can be very exciting, safe, and seaworthy.
Which compromises should you make when selecting your catamaran? It all depends on how you will use her. Catamaran Guru helps new and veteran multihull owners select the right boat for their dreams at no cost! The yacht seller pays broker commissions so our advice from gleaned from thousands of boat-buying transactions is free to you. We will help you find right boat, the right program, or the right situation. If you want to explore more on your own, visit our buying a catamaran section.
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The Catana OC 50 Catamaran, the latest addition to the Catana Ocean Class series,
For more than 30 years, we have been a part of the catamaran community and created Catamaran Guru™ to encourage and educate all the aspiring sailing out there. We understand the dream of traveling the world by catamaran and created a one-stop-shop to make that dream a reality for you.
Gemini sailing catamarans of Yacht A Fun’s 1997 vintage were designed such that small wave ripples are caught in the square shoulders of the inner hull transition. When at sea, the small sounds are masked somewhat by the boom sound of the bridge deck being pounded by full sized waves and swell.
On a mooring, or at anchor, small waves reach the hull shoulder’s combination of bow to stern slope having 90 degree horizontal profile- and creates loud popping sounds as the wavelet ripples catch air pockets which explode with “plop, plop, plop” voices. Some Gemini catamaran owners refer to it as “wave slap”.
Blue Marker helped outline the area before taping up the guide line
One CAN get used to the sound- kinda like living next to an airport! Diann and I swore we’d do an up fit modification similar to the one effected by Jim Faughn on his Gemini named Freedom. Thanks to Jim’s emailed coaching, our up fit is under way.
New epoxy doesn’t bond onto gelcoat with lasting results. Therefore one has to grind / sand the gelcoat down to the underlying fiberglass. Sounds simple doesn’t it.
Our up fit affects only six lineal feet of added 45 degree filler foam and new epoxy / fiberglass. How long did it take me to sand out 1 ½ inch ribbons (which totaled about 26 lineal feet) ? Try 12 hours while wearing a Tyvek suit, head sock, goggles, and respirator mask.
The Rockwell vibrating mult-tool’s triangular “hook and loop” head didn’t hold up to the task. So, off to Lowes we went to acquire a cheap pointy ended Black & Decker sander. The B&D sander held up- though I used over two dozen sanding pads!
Some surfboards are custom made with polystyrene. We chose the denser version called blue board. Each board, from that 4 by 8 panel, had to be successively custom fitted to the hull shape. To work through the process we re-purposed fifty drywall twist-function anchors as screws.
Once boards one and two were temporarily laminated via the “screws” we could hold them in place to mark board #3- and so forth thru six ½ inch foam board/strips.
Once comfortable with the laminated fit, the screws were removed, Gorilla glue added to areas of foam which had been sand paper scuffed, and the screws re-placed as guides and pressure points for the glue.
When both sets of slap stopper foam had been glued, we put small sections of plywood on top to press the glue joints as firmly as we could- and let it sit all night.
One inch by 2 inch furring strips were used to support the sections while being attached using 100% silicon adhesive. The adhesive’s purpose was to keep the foam in place:
while being dressed down to the final shape;
while being “faired” with West System epoxy 105 resin, 206 hardener, and 410 filler; and
while having three layers of fiberglass cloth laminated (over the faired foam) onto the hull’s
fiberglass ribbons.
Once the fiberglass / epoxy has cured, gelcoat will be applied; and bottom painting can be completed.
Conceiving a boat improvement project, “priceless”. Executing the project- very time consuming!
The story / blog of Yacht A Fun, a Gemini catamaran sailboat, traveling the ICW and east coast with insights to the extended cruising life. Bridge deck slap
I’m a recent new owner of Gemini hull #828 and I’m very interested in how effective your bridgedeck slapping fix turned out. The slapping & pounding are very frustrating so I’m trying to find a fix to reduce these wave effects.
Mike Krattli Maple Valley, Wa.
Slap fix seems to be effective. More use in July should help confirm the results.
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Brix Marine 3814-CTC-Offshore-SWA 2023 Brix Marine Hammer Catamaran now available! Twin Mercury V12 600 HP Length 38' Beam 14' Self bailing aluminum decks BEACHCOMBER landing gear for foot traffic...
COMMENTS
The bridge deck is essentially the part of the catamaran that you stand on. It is the space between the hulls. It's not just the saloon but also the cockpit and the forward anchor lockers. ... So those are the priorities. A high bridge deck underneath, a sloping front that starts as far back as possible, and a higher cockpit then is a good thing.
The potential of the catamaran hull form, which is so impressive when sailing at 8 to 10 knots in 20 knots of breeze in protected waters, can be quickly reduced to 5 knots by pounding. Yes, a very low bridgedeck cat can lose 3 to 4 knots of boat speed with a major pound. Read more about bridge deck clearance.
Avoiding slamming or pounding of waves against the underside of the bridgedeck, can make all the difference for the comfort of the crew and safety of the vessel. The slamming phenomenon can both be nerve wracking for the crew and damaging to the boat. As a rule of thumb, we believe that clearance of between 5 and 6% of the LOA of the catamaran ...
Part 3: Building a Bridgedeck. Building the bridgedeck is the key piece of fiberglass catamaran strength. To be able to build a boat which can handle all these twisting and torsion forces, creating that "box" to add the strength, catamaran builders take one of several approaches.
I would love to have a higher bridge deck clearance, but taking stuff off the catamaran involves people giving up some of their stuff. Not easy. I would love to have a higher bridge deck clearance by getting a bigger cat, but then there are all sorts of new challenges sailing and taking care of a larger yacht, not to mention the much bigger ...
The cockpit contains navigation and steering equipment and is from where the sails, rudder, and engine are controlled. Deck; is the top part (roof) of a catamaran covering the hulls and bridge deck. The deck is made hard enough to walk on. To the deck, attaches lifelines and other equipment.
The Space Between. An In-Depth Look at Bridgedeck Clearance for Catamarans. CurrieBridgedeckclearance (the height of the bridgedeck above the water) is crucial for cat-amaran seaworthiness and cr. w comfort at sea. Because bridge-deck clearance can be seen at a glance, and is easily measured, even an inexperienced sailo.
The WALLER 880 Cat is a full length bridge deck catamaran designed for family coastal cruising, with the occasional foray further afield. Full length bridge decks have several advantages in smaller cats, in that they provide a stronger hull structure, more deck space, are easier to construct and eliminate the need for expensive bow beam structures.
Bridge deck clearance ratio (BCR) starts to be good from 6% of LOA. On our models, the bridge deack clearance is as follows: ORC50: 37,4 inches. ORC57: 42,1 inches. Should you have any questions about other measures, or want to know more about our boat specs, please let us know! Speak to you soon. Fair winds,
Cruising catamarans should have a high bridge deck clearance. If the bridge deck clearance is too low, the waves may pound against the bottom of the bridge deck. This pounding can cause discomfort and fatigue for the passengers and crew and potentially reduce the catamaran's speed. The height of the bridge deck clearance needs to be ...
I have put together a design for a catamaran to meet my list of requirements: 1. catamaran, max 34 ft. LOA, 21 ft. beam. 2. good bridgedeck clearance…32 inch minimum. 3. minimum open bridgedeck, well back from bow and stern. 4. center of gravity at or below bridgedeck, with all tankage, engines, food storage near waterline.
The WALLER 880 Cat is a full length bridge deck catamaran designed for family coastal cruising, with the occasional foray further afield. Full length bridge decks have several advantages in smaller cats, in that they provide a stronger hull structure, more deck space, are easier to construct and eliminate the need for expensive bow beam structures.
Strike 15 trimaran at speed. 28ft Skoota in British Columbia. 10ft 2 sheet ply Duo dinghy. 24ft Strider sailing fast. 36ft Mirage open deck catamaran. Bridgedeck Slamming. People are right to be concerned about bridgedeck slamming on catamarans. Having said that, it is usually a comfort problem rather than a structural one.
Bridge deck clearance (BDC): BDC affects the amount of noise in the boat from wave slap, especially while going upwind. We think a catamaran with about 30 inches of clearance is ideal. Increasing the BDC means more windage, which is a negative. Much less than 30 inches, and wave slap becomes a problem in rowdy sea conditions.
(1) Interested in comments from Catamaran owners re Bridge deck clearance. I have heard reports about low bridge deck clearance causes Slamming and pounding of significant proportions when sailing to windward. Comments please. (2) Some designs have .500m clearance others .700m and I notice the latest designs on some are rising to .950m and 1.2m
HOW MUCH 40-50ft ! Bridge-Deck clearance on a Catamaran. Lets face it guys, most of the Production Cats do not have enough clearance or the have many shelves, bumps, and things that should not be there. If it is slamming, it is causing Drag as well. My 381 Catana does not slam with 800mm of clear space between the hulls.
Rotten deck core. How detrimental? gansett: Construction, Maintenance & Refit: 37: 02-07-2020 23:56: Ocean-Going Catamaran Size and Bridge Deck Clearance: tallboy: Multihull Sailboats: 18: 05-10-2014 17:12: Rotten Deck Core Around Windlass: Philip R. McGovern: Deck hardware: Rigging, Sails & Hoisting: 18: 14-10-2010 06:16: Rotten Deck & Cabin ...
Catamaran Bridge Deck Clearance. ALL catamarans slam (waves hitting under the bridge deck). The noisy and sometimes disconcerting slamming takes getting used to. The first catamaran I ever sailed an ocean passage on was a Shuttleworth 44. In the early 90's and even today, it is considered to be a good design. However, after a few hours of ...
Posts: 11,832. Re: Lifting a catamaran from under the bridgedeck. All you have to do is make sure they catch it at the main structural beams. Those are the bulkheads that go all the way across the boat from port to starboard. One is located all the way aft. The other is located typically underneath the mast.
Bridge Deck Slap- Gemini Catamaran. Gemini sailing catamarans of Yacht A Fun's 1997 vintage were designed such that small wave ripples are caught in the square shoulders of the inner hull transition. When at sea, the small sounds are masked somewhat by the boom sound of the bridge deck being pounded by full sized waves and swell.
Brix Marine 3814-CTC-Offshore-SWA 2023 Brix Marine Hammer Catamaran now available! Twin Mercury V12 600 HP Length 38' Beam 14' Self bailing aluminum decks BEACHCOMBER landing gear for foot traffic... CL. chicago > north chicagoland > for ... Custom Fly bridge bench covers 1-port, 1-stbd, Stamoid Black c/w SS fasteners & PTFE thread.
Location: Kingston / Thousand Islands, Ontario. Boat: C&C 35 Mk.II. Posts: 343. Re: Ocean-Going Catamaran Size and Bridge Deck Clearance. Regarding bridgedeck clearance: Recommendations vary, but the consistent advice from most sources is along the lines of "the bridgedeck shouldn't slap on the wave crests".
Join Date: Nov 2023. Posts: 10. Rotten Bridge Deck Catamaran? I'm considering buying a 1990s catamaran - first boat so please help! It has balsa cores above the waterline. Solid fiberglass below. The outside decks all feel strong no sponges bits.BUT the bridge deck cabin sole is spongey and lifting the carpet shows the below.