Multihull Structure Thoughts

Discussion in 'Multihulls' started by oldmulti, May 27, 2019.

  1. rob denney
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    rob denney Senior Member

    Apart from the old Enza, do you have any details of these boats? In particular, performance numbers and photos of them sailing in a breeze?
    Ta.
     
  2. oldmulti
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    oldmulti Senior Member

    Rob, beyond the 25 foot test tri and old Enza, I cannot find other boats. I got confused with the Beneteau Wingsail which was developed from Mati Brieu (?) schooner that a french guy spent several years of ocean crossing.

    A few interesting things I found are: Laser 2 part wing sails in 2014. Wingsail Laser World Championships | Tropical Boating https://www.tropicalboating.com/2014/02/wingsail-laser-world-championships

    A 18 foot norse boat with a 2 part reefable wing sail Prototype de voile aile souple à deux volets (AC 18) : Ailes souples / Soft wings http://www.voiles-alternatives.com/viewtopic.php?f=3&t=136

    An interesting study of rigs for ships “Wing Sails for Hybrid Propulsion of a Ship” https://pdfs.semanticscholar.org/583a/c683c731cd1aa229c1938cb352953c4e3ed1.pdf

    The final 2 are just general information.

    https://www.boatindustry.com/news/2...-is-no-longer-confined-to-competition-sailing

    AYRO chooses Caen in Normandy to produce its Oceanwings®, wind propulsion system for maritime transport - Workboat365.com https://workboat365.com/commercial-marine-news/power-propulsion-news/wind-propulsion/ayro-chooses-caen-in-normandy-to-produce-its-oceanwings-wind-propulsion-system-for-maritime-transport/

    I will search further for jpegs and info.
     

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  3. peterAustralia
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    peterAustralia Senior Member

    In regards to that large 90ft trimaran, I suspect those windows close to the waterline create a degree of lesser structural integrity, plus a possible place for waves to enter if by chance they broke, I am sure they are very sturdy. The wide stern would appear to be some weakness in a following sea. Apart from that, appears reasonable for what it is
     
  4. rob denney
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    rob denney Senior Member

    Ta. The laser looks interesting, pity there is not more info available.
    There are others that I know of, including an Etchells on Pittwater, but none appear to have resolved the ability to reef/lower the sail with a leading edge that doesn't dimple in a breeze. The exception is the WISAMO rig, but it requires fans to pressurise the wing.

    Keep up the good work.
     
  5. Flotation
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    Flotation Senior Member

  6. oldmulti
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    oldmulti Senior Member

    The following is a modern high performance cruising tri that is currently being built in France. The design is by Philippe RIVIERE and is initially called “Objective Rhum 39”. The tri is 39 x 32.9 foot with a weight of 6720 lbs and a displacement of 9000 lbs. The 50 foot rotating carbon mast carries a 565 square foot main, 182 square foot staysail, 330 square foot jib and a 685 square foot code 0. The mast was moved further back during the design period. The main hull length to beam is 12 to 1 and the float length to beam is about 16 to 1. The draft over the main hull daggerboard is 8 foot. The T foil rudders on the float hulls as are the C lifting foils. Are you starting to understand the name of “Objective Rhum”.

    The main hull is U shaped by Philippe RIVIERE to get very good performance with larger and more flat hulls. The shapes of the back of the main hull have already been modified with more volume, the concave shape has been removed to a flatter stern. The floats are large and full. The design, with slightly V-shaped bottoms, should encourage a more comfortable passage in the rough sea and above all should be more tolerant of over sailing.

    The above numbers indicate a very high performance tri for its conservative rig. The thin hulls and light displacement helps improve its performance. To match the concept the accommodation is limited to 2 double berths, a galley, seating and toilet. The cockpit will provide an excellent sail handling and steering area. The cockpit is indeed very wide, deep and secure, a bit like on racing boats. And it will be possible to add an articulated bench seat along the rear beam.

    The Trimaran 39 intended to be built in foam sandwich or strip planking by a shipyard (Technologie Marine are planning on launching the production of the first example) or for amateur construction foam sandwich or strip planking. The jpegs show the first build which looks like strip plank foam. No mention of resin system but I am assuming at least biaxial, triaxial glass and vinylester resin on the shell with carbon fibre unidirectional reinforcements in the foils and cross beams. I would not be surprised if the tri was all foam carbon fibre with this weight.

    This is a very high performance simple cruiser that can be built at home by a good amateur builder. Well done (Philippe RIVIERE / Yacht Designer | ARCHITECTE NAVAL http://www.philipperiviere.com/wp/)
     

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  7. garydierking
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    garydierking Senior Member

    Cruising tri...right. The coral heads will love all those appendages.
     
  8. oldmulti
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    oldmulti Senior Member

    I need to update the threads indexes. My apologies if this is a repeat. The MX 88 Volante is designed by Adam and Vlad Murnikov of mxDesign as an attention seeking design concept that I hope someone will spend $12 million to build one. The MX 88 Volante is 88 x 31.5 foot and displaces 55,100 lbs. The 2 freestanding 2 part wing sail with a total sail area of 3014 square foot. The wings are power actuated for chord adjustment and are computer controlled if required. The hulls length to beam is 11 to 1. The draft is 4 foot over the rudders and up to 15.75 foot when the curved C foils are fully down. As you will see later the boards can serve multiple functions.

    An interesting statement is “To be feasible for an offshore performance cruising catamaran, the wings need the ability to reduce area in heavy weather. One way to reduce area is to have the back sections of a two-part wing retract into the forward sections. Another option is to have part of the wing surface flexible so that it can be furled.” And “Engineering of the ‘reefing’ devices is still ongoing as we strive to find the most simple, rugged and reliable solutions. With modern techniques and advanced composite construction, all of these goals can be achieved.”

    The cats beam is relatively narrow but due to the MX 88 size the stability will be sufficient to handle the sailing loads. As the wing sails will be computer controlled. Adding to the MX 88-Volante performance are also advanced hydrofoils, main C-foils and rudder T-foils. They decided that for a cruising offshore catamaran full foiling is a liability and could prove dangerous. Instead they designed foils to offset up to 75% of the boat’s full displacement, significantly reducing drag and improving performance.

    The designers said. “Several foil configurations were explored, one of them utilising an articulating mechanism, which allows us the ability to place the main foil closer to vertical while sailing upwind to increase lateral resistance, and closer to horizontal for reaching legs to increase lift. We expect an upwind speed of 15-20 knots, depending on the sea state, and reaching speeds up to 35 knots.”

    There is a nicely appointed guest suite in the starboard hull aft and two smaller cabins forward that could be used for crew or occasional guests. The entire port hull is one big owner’s suite, with plenty of storage and lavishly equipped head featuring double sinks, large shower and even an enormous bathtub. The bridge connecting two hulls is one large open area featuring a spacious galley, salon with an entertainment center and huge wheelhouse up forward, equipped with comfortable captains chairs. All boat’s functions can be controlled from this command center. A vast lifting swim platform, essentially your own private “beach’” spans the entire width between the hulls, creating an ideal area for sunbathing, swimming and launching water toys.

    Construction would be all carbon fiber infused over a foam core. Using pre-preg carbon (carbon fiber combined with heat activated epoxy) would further reduce weight but add very considerably to the build cost and complexity.

    The jpegs give the idea of this very interesting design.
     

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  9. oldmulti
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    oldmulti Senior Member

    An update on Running Cloud, one of the first foam glass trimarans built in USA. Richard Flint designed and built over 4 years and was started in 1968 and the tri was finally finished in 1972 after being built as a part time project at his boatyard The tri is 52 x 31.75 foot displacing 14,000 lbs with a 55 foot mast that carries a 475 square foot mainsail, 231 square foot staysail, 540 square foot lapper, 850 square foot genoa and 137 square foot storm sail. The main hull length to beam is 12 to 1. The float length to beam is 15 to 1. The boat has 2 daggerboards one in the fore peak in front of the forward crossbeam and one in the cockpit. This was to help balance the boat and provide more space in the main cabin.

    Richard was 25 when he designed it and 30 when he launched the boat. He spent $20,000 (in 1973 $) building the boat. He made nearly everything himself including the mast, sails, blocks, steering gear etc. Richard extended the tri 3 foot to 55 foot after initial sailing to improve reaching and off wind speed.

    The internal accommodation is generous with a rear cabin double berth, a double and a wide single in the main cabin and a good galley and dinette with a proper bathroom forward.

    So why do I like this tri. This boat made a California to Hawai'i passage in eight and a half days in 1977. It also in 1986 crossed the Atlantic in under 14 days in a “cruiser rally”. He cruised many global miles. Richard Flint died in 2005 and the boat was sold to a new owner. The new owner comment was “I did not race Running Cloud until the Kings Cup in Asia which we won in 2006 and 2007 in the biggest most serious race in Asia. One of the best regattas in the world for any cruiser or racer to be in. I also raced for two seasons in all of the other races in the area from Langkawi and Singapore. I returned to the US going around south Africa in 2008-2009 and raced in Antigua race week 2009 and won.”

    In 2013 Running Cloud was in Beaufort, NC and sailed the Atlantic to land in Cork Ireland in 2014. A real engine and drive system was put in Running Cloud for the first time, allowing it to actually motor over 4.5 knots. Not that it is usually needed. Then it was Scotland, Caledonia canal, east coast of England, Amsterdam, up the Rhine across the alps in the MDK and down the Danube. Right now (2019) the boat is in Varna Bulgaria waiting for Europe to allow Americans to re enter the continent. If you wish to follow Running Clouds current travels use the following Google Maps web address: Running Cloud - Google My Maps https://www.google.com/maps/d/viewer?hl=en&mid=1x_J04zBAaWzm-29G3f_kIBI0U0ABqoT6&ll=52.09424720000001%2C5.080625900000015&z=10&fbclid=IwAR3JjJ3AqJhnJqS_Dy7jxC8EWRbzEZAXmuJHfMH7mvl8h5Z54mX0lIw9aa4

    The jpegs give the idea of a competitive 50 year old trimaran that will still embarrass many modern designs. You just need a good basic design, a moderate rig with light weight and you will have a 20 knot tri that has no problems with 250 mile days. A very impressive boat.
     

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  10. Scuff
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    Scuff Senior Member

    Bitchin' Oldmulti.
     
  11. guzzis3
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    guzzis3 Senior Member

    12:1! Goodness. It couldn't help but be fast ..
     
  12. oldmulti
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    oldmulti Senior Member

    This is a story about a trimaran designed by Andrè Allegre (designer of Pen Duick IV/Manureva 65 foot racing tri) and put in production in February 1969. 60 of these tris were built. Now the fun stuff. The trimaran started out as a 26.3 x 15.75 foot cruising tri claiming to weigh 2460 lbs. Magazine articles at the time said the weight was wrong and the tri weighed at least 2900 lbs. The next version was 27.4 x 15.75 foot followed by a 30 x 16 foot version. The tri we will discuss is Allegro which is a 30 x 16 foot version with a weight of 2900 lbs and a displacement of 4000 lbs. The 39 foot aluminium mast carries a 183 square foot mainsail, a 86 square foot jib, a 269 square foot genoa and a 320 square foot spinnaker. The main hull length to beam is, if sailed at the correct displacement, is about 8 to 1. The submersible floats have a length to beam of 14 to 1. The draft varies between 1.3 and 4 foot over the centre board. The rudder should be a kickup but some are fixed on the stern.

    The tri was designed to be trailable with floats and part of the wings able to be disassembled from the main hull. I would consider the tri transportable more than trailable. The cross arms are actually bolted on aluminium tube structure with a fiberglass walkway covering.

    The accommodation is a double berth forward, small toilet and the main cabin contains 3 single berths and a small galley.

    The construction is listed as polyester e-glass with no indication of foam. In 1970 single skin solid glass was not uncommon in this size. There may be some balsa in the decks (I am guessing). The floats and main hull ends are filled with foam to provide flotation. The aluminium cross arms are bolted on with 8 x 18 mm bolts per cross arm onto backing plates in the main hull.

    The performance of the tri is reasonable with one skipper saying: “The tri in force 2-3 reaches 6 to 7 knots at full load and it is a pleasure to overtake all monohulls of the same size! You have to be vigilant about the settings of the sails, bear down and gain good speed after a tack before tackling the wind. In moderate wind (force 3-4), the tri tacks between 90 and 100 degrees with between 6 and 7 knots close-hauled. In calm seas, with force 3-4 the speed climbs to between 8 and 9 knots.” “In rough weather and waves we tack through 120 degrees. On the positive side, although the ALLEGRO is relatively low on the water, the cockpit does not get wet and we remain sheltered. On a reach, I have hovered at 12 knots for 2 or 3 minutes. The record measured was 14.83 knots on reach with a swell of 2m.”

    Good so far, then you find this series of comments: “One of them capsized at Cap Fréhel by force 5 (because of the sea). This fairly fast boat, it is true, can turn out to be very dangerous in heavy seas and a wave abeam very easily turns it over, I know what I'm talking about, alas. This boat is dangerous in rough seas because in this case its submersible float downwind sinks into the water and causes a kind of trip to the boat which quickly causes it to overturn. This submersible float system has long been abandoned by other builders.” And “My boat Allegro capsized in the English Channel at night, overturned by a crooked wave (the leeward float sank into the water and caused a kind of trip which caused this overturning). You should know that I am unfortunately not the only one to whom this has happened.”

    As you can see in the jpegs when this tri is pushed hard you need to be very careful. Relatively narrow beamed submersible float tris were thought to be safer by giving you more warning. Unfortunately, most sailors understand the lifting of the main hull more than they understand the reducing stability of a float submersing under the waves. If sailed conservatively any tri will be OK. But big waves, relatively narrow overall beam and submersible floats are a bad combination.
     

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  13. bajansailor
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    bajansailor Marine Surveyor

    Re Running Cloud, she was in the 1986 Atlantic Rally for Cruisers (ARC) from Las Palmas in the Canary Islands to Barbados.
    I crewed on an American cruising yacht (a heavy displacement CSY 44 cutter) in that Rally, and it was brilliant, with an excellent camaraderie amongst everyone.
    I seem to remember though that the American couple who sailed Running Cloud were a bit aloof, and didn't really 'fit in' with the 'cruisers' - I think that Running Cloud won on elapsed time of about 14 days (an average of about 200 miles a day). And then they didn't stick around afterwards for the parties and the camaraderie - they had made their point, won the 'race' (it was a race, rather than a rally, to them, absolutely) and then absconded.
    But it is good to see that RC is still going strong, excellent! Thanks for the update about her.
     
  14. oldmulti
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    oldmulti Senior Member

    The Windelo 50 is a new performance cruising cat designed by Christophe Barreau and Frédéric Neuman was designed and built to be environmentally friendly. The Windelo is 50 x 26 foot with a weight of 25,000 lbs and a displacement of 33,400 lbs. The 69 foot mast has a 990 square foot mainsail, 463 self tacking jib and a 1732 gennaker. The length to beam is about 9 to 1. The lower hulls are angled out 6 degrees which provides a better waterflow on the lee hull as the cat heals. It also provides slightly more stability. The draft over a fixed keel is 5.1 foot or the daggerboard option has a draft of 7.6 foot with a draft over rudders of 4 foot.

    As a comparison the Outremer 51 is 51 x 24.8 with a weight of 25,000 lbs and a sail area of 1409 square foot compared to the Windelo sail area of 1453 square foot with main and jib. The Outremer 51 is a real performance cruiser. Translation the Windelo 50 should have very good performance especially with the daggerboard option. To quote the builder: “You have a yacht capable of munching up the ocean miles at anything up to 20kn under sail.” A test of the Windello 50 produced “With eight knots of wind, we were able to match windspeed and boat speed provided we used the big gennaker. Sail handling was very simple and at the helm you had a really good view of the sails thanks to the forward cockpit and twin helms.”

    For maximum performance a Sport version of Windelo 50 have saved 500 kg by removing, for example, the crossbeam forward, and replacing it with a longitudinal fore beam. All the materials used have been carefully chosen to limit weight.

    As per usual you have many accommodation options in the hulls which can contain up to 4 double berth cabins and attached toilets. The main cabin focus is different. The forward part of the cabin directly behind the mast is a enclosed steering, navigation and mast rope handling area. There is a “window hatch” that allows access to the foredeck if required. Behind the forward enclosed cockpit is the galley, dinette, entertainment and seating area in a integrated cabin cockpit combination.

    The structure and build technique are interesting and this is where the real environmental gains are done. The structure is made from a new environmentally-friendly robust composite sandwich, mixing basalt fiber and PET foam from recycled plastic bottles. The basalt fiber is spun in Russia and woven in Belgium and provides an impressive mechanical resistance with a black carbon-like finish. This new innovative composite cuts the carbon emission footprint by almost half compared with traditional GRP composite manufacturing methods. Basalt is a natural volcanic fibre which offers vibration resistance and durability while still maintaining a high strength to weight ratio. The other great asset it possesses is that it is naturally produced and has no toxic additives. PET [Polyethylene Terephthalate] is made from old bottles which is crushed into very small pieces then melted again in order to create the PET foam. During the fabrication process, the PET core produces half CO2 than other PVC cores. It’s light and environmentally friendly and used in the hull construction and many of the wood laminates in the interior are cored with PET. The company has filed patents on their new sandwich with alternative fibres to glass. They’re still working on the resins to get the best environmental outcomes.

    The classic construction of a cat mainly uses female moulds. This solution imposes costly investments and makes production less flexible. "When they talked about the Windelo project with the boating industry, they always talked about moulds. It blocks them. So, I thought of an assembled solution, with very large developable panels built on marble, a technique that already exists. I am convinced that models must change quickly and this makes it possible to adapt." For finer water intakes, Windelo keeps a bottom of hull mould, but the rest of the sailboat is made of assembled panels. The manufacturer thus limits the environmental impact associated with unnecessary tools and retains the possibility of customized boats.

    This is a very good design, with a good environmental approach to building. A lot of the materials could be used by a home builder if you wanted to reduce your environmental impact. The jpegs give the idea.
     

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  15. oldmulti
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    oldmulti Senior Member

    Part 2 of Windelo 50. Mainly the build.
     

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