Fantasy Trimaran

Discussion in 'Multihulls' started by FantasyTrimaran, Sep 11, 2019.

  1. FantasyTrimaran
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    FantasyTrimaran Junior Member

    Hello everyone, is it possible for me to make a thread in which to: Ask "101" questions; Edit the opening post successively through time with answers to those questions as the thread grows; And to also add cross-references or links of other "question-relevant" posts from this website in order to build up a comprehensive and in-progress locus of knowledge that I can refer to, ponder in and learn from?

    On the other hand maybe threads can't be edited past a certain time-limit? Or questions are spread out exclusively?

    Thank you
     
  2. gonzo
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    gonzo Senior Member

    If you edit the opening post, the answers will make no sense and thread will have no continuity. You can simply add requirements or questions as you go along.
     
  3. FantasyTrimaran
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    FantasyTrimaran Junior Member

    Alright, and thank you for your reply.

    So, my first question is then - what is the largest size trimaran, of plywood and epoxy and fibreglass cloth structure, that can be built?

    I am thinking about the structural limitations and whatever legal license or whatever it is that governs that part of the equation too. (Someone mentioned in a thread about the limit of a trimaran being 24metres under "European law", whatever that means? I don't know what it is in the UK and nor do I know anything about the legal side of things - it doesn't seem to make sense to me)
     
  4. gonzo
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    gonzo Senior Member

    What jurisdiction are you building under? The UK is more relaxed than say Spain. Are you asking for maximum size based on structural integrity? Ships of over 130 meters were built in wood with metal bracing, which would be somewhat equivalent to fiberglassing the wood.
     
  5. FantasyTrimaran
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    FantasyTrimaran Junior Member

    Yes - how feasible based on structural integrity, and, legal concerns.

    It would be the UK, in theory, it's just a fantasy so it's just ideas - daydreams in speculation but grounded in reality, just in case.

    130 metres is massive - would a trimaran made of plywood, epoxy resin and fibreglass cloth of somewhere between 30metres to 40 metres be buildable by non-specialists, non-professionals? Or down to 24metres (depending on the laws/whatever that I have no idea about at this time)?

    There seem to be a lot of people who have built pretty big boats of various sizes, like in their back yards or something with their own tools and that - ones that come to mind are 38feet and 40feet, so what's that - about 12 metres I suppose. Well what about something three times that length overall? 36 metres?

    36 metres built along the ORMA proportions? (but obviously somewhat larger scale, but not monstrous)
     
  6. Corley
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    Corley epoxy coated

    The problem is ply starts to become pretty inefficient as a structural choice past a certain point. You could say that Banque Populaire V was basically a very large ORMA and was about 30 metres, beam naturally decreases with size as righting moment increases, carbon/composite was their material choice to be competitive in round the world racing. I'm not sure why you would build a boat like that though unless to race. They are very expensive to maintain and have very little accommodation. Another thing to consider is the time required to build such a large boat which is enormous even a 12 metre multihull is a big commitment in time and cost of materials/labor. Bigger isn't necessarily better if smaller is adequate to fit your needs whatever they may be.
     
  7. oldmulti
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    oldmulti Senior Member

    I will give you the structure of the Piver Empress trimaran. The boat is 64 x 32 foot weighing 44000 lbs carrying 1500 square foot of sail in a ketch rig. This boat would displace 60,000 lbs. Piver sold home build plans and several were built by professional boat builders, No home builders that I know of. This boat was a charter machine with huge internal space 18 berths and 2 floors in the main hull etc. Float and main hull 15 mm ply sides 18 mm ply bottom. 30 x 140 frames on 12 mm ply at 70 to 950 mm centre lines. Stringers 30 x 140 mm on flat in main hull Float stringers 25 x 95 mm flat at 400 mm centre lines. Decks 12 mm ply with deck beams and stringers of 30 x 140 mm. Cabin roof and sides 15 mm ply with frames and stringers. Underwing 18 mm ply wood. Rudder shaft 1.5 meters long by 65 mm solid stainless steel. This boat is not fast. Or you could build a Cross 80 footer, better design faster boat if one was ever finished. It only took 18 sheets of 9 mm ply per bulkhead. These boats are massive and consume large amounts of material. For an Empress you would be using at least 500 sheets of 12 mm plus plywood and tons of timber let alone the several 44 gallon drums of glue etc. Anything is possible with enough money and time (20,000 plus hours or 10 years full time). Good luck.
     

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    Last edited: Sep 11, 2019
  8. gonzo
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    gonzo Senior Member

    Keep in mind that you will have to be moving and rolling over 60,000 lbs. Even each hull is probably about 25,000lbs. At the size you are referring to, the weights will at least triple. A very experienced and physically fit shipwright could do it, with a lot of difficulty. A first time project for an amateur is unrealistic. Every amateur I've seen, learns enough about boatbuilding mid-way through the project. At that point, he looks at the project and realizes that it is poor quality.
     
  9. FantasyTrimaran
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    FantasyTrimaran Junior Member

    When I say proportionally based on an orma - I mean only the ratios of LOA/BEAM/MAST. As far as shape - no, that narrow shape just as you say is for racing rather than accomodation and not at all what I had in mind - I ought to have been more specific. Shapewise I mean wider, more spacious, more of a cruiser and naturally that much slower. The AVATAR trimaran operated by Ozsail out of Queensland Australia is more the type of shape, maybe wider in the main hull even, but that one is I think somewhere around - LOA: 21-22metres BEAM: 16-17metres. I don't know it's mast height.

    What does it mean about the righting moment changing with .. what? Overall size? Is it due to the wave-size? I haven't grasped the fundamental reasons for optimal LOA-to-BEAM ratios changing due to scale. What is the principle behind it? Would it be a particularly inferior design choice to be "square" at such a size of 36Metres? (As a side note - I know that would never be feasible in a marina - but that wouldn't be the place for such a boat anyway.) I have read this before, but I just like the spacious width of more square trimarans, even though most of it is just net.
     
  10. FantasyTrimaran
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    FantasyTrimaran Junior Member



    36 Metres would be ideal, but I know that sometimes boats come in series. So let's shift over and look at the little sibling - the 24 metre version.

    What do you all think - along the same questions and so-on, about a 24 metre version?

    LOA 24m
    BEAM 24m

    Built square-based like an ORMA but much more spacious, more of a cruiser design, wider in the main hull - maybe 6 metres main hull width making the main hull one-quarter of the beam overall and the floats 2m or 2.5 metre wide each, which I know is much different than the thin hulls of an Orma. (What appeals to me about the Orma's are the length to beam to mast proportions or ratios - not their slender racing hulls - speed is a valuable quality in a boat to be sure, but at that scale those hulls are just too narrow to be comfortable.)

    So if an Orma is 18 metres LOA, 18 metres BEAM then a 24 metres trimaran, albeit in a much more bulky shape, wouldn't be unfeasable, no?
     
    Last edited: Sep 12, 2019
  11. FantasyTrimaran
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    FantasyTrimaran Junior Member


    That is a big boat, and that design looks hefty. I like the open netting for the wings though, rather than housed. Perhaps that makes my prefrerence a compromise between proper speed and proper comfort, but it's so. The smaller version that I am also considering would be 24 metres or 80 feet so not so far off on that one dimension, but I don't think that it would be quite so substantial owing to open wings.

    About the two floors of the Piver 80 - what sort of height is that? If the ceilings are too low then the boat can feel too claustrophobic to some people - if it's a height that one can stand up in and stretch their arms overhead without touching the ceiling, then all the better. I know that many boats are "compact" and that's just how it is for most of them, but space is what I am going for, atleast in some of the areas.
     
  12. oldmulti
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    oldmulti Senior Member

    Fantasy Tri. The basics are that a tri like Avatar is a $1 million build. Sideline, it nearly sent 2 people broke in the process and John Cadwaller had to fight in NZ courts to get it to Australia. Trimarans depend on their weight and width for stability (ability to hold sails up in stronger winds). The wider a tri is the more stability, the more strength is required in the cross beam structure to hold the boat together. A 24 x 24 meter trimaran displacing 40,000 lbs would require about 30 sq inches of carbon fibre on each of the top and bottom of each cross arm. This is not cheap or easy to build. ORMA tris take 30,000 plus hours to build well. Tris this wide take a lot of very good design work to get balanced correctly (sail consistently on one course) whilst sailing under a variety of conditions. The sail area to drive them fast is large and VERY expensive as is most of the deck gear if you want high performance. Main hull shapes with flair are very possible for accommodation. Look up Kurt Hughes multihull designer web site for his 71 foot trimaran design. It will give you the idea. Kurt Hughes Multihull Design - Catamarans and Trimarans for Cruising and Charter - 71' Tri w/ Flared Main Hull http://www.multihulldesigns.com/designs_stock/71tri.html
     

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  13. Corley
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    Corley epoxy coated

    Square trimarans are only really applicable to smaller, lighter platforms as a means of providing adequate righting moment. Consider as a basic means of calculating it as platform weight multiplied by half beam. Bigger platforms are naturally heavier so righting moment increases as a byproduct of that so the need for beam decreases. A 24 metre wide platform would be very heavy and the righting moment becomes excessive it's possible to have too much of a good thing and boat design is all about balance. A boat of that type would be very stiff in motion not to mention how impractical a square platform of that size is. The biggest square platform I can think of was the mighty BOR trimaran in the Deed of Gift match for the America's Cup which was a super specialised inshore racing trimaran for light weather usage 90' wide iirc but even in that case they extended the floats so the platform was undersquare.
     
  14. FantasyTrimaran
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    FantasyTrimaran Junior Member


    So are you saying that a plywood construction of 24 x 24 metres would splinter in the wings under it's own weight under any "flying" moments?

    Is carbon fibre something that is within the capability of an amatuer? Would plywood - or any other type of wood for that matter, be sufficiently strong in the estimated tensile and compressive strengths (I presume that is what you meant when you said about such a 24 x 24 metre trimaran displacing 40,000 lbs needing 30 sq inches of carbon fibre on the top and bottom of each of the four arms) to be a reasonable substitute? What about internal-structuring within each cross-arm, like bones have?

    How did you figure 40,000 lbs - how do I calculate the displacement of a trimaran?

    Do sails for a trimaran such as the 24 metres have to be particularly expensive? I can speculate that we are talking about materials that are very strong in order to resist tearing under the immense pressures of both the wind and the mast/ship that it's attached to, and that such material must also be as light as possible - but must it automatically be so? Are there heavier sail-materials that are cheaper or such?

    I don't suppose that the version - this 24 metre smaller sibling - would be state-of-the-art or anything, and it's not for competitive racing, though presumably it must have an okay speed.

    30,000 hours to build an Orma trimaran seems crazy - that's 1,250 days, of 24 hours... Something seems very inefficient there, unless it is because we are discussing the realm of high-spec, light-weight, racing trimarans. If we are then my mistake - I am meant to be talking about "home-built" cruising trimarans, of appropriately lesser speed expectations and lower-spec.
     

  15. oldmulti
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    oldmulti Senior Member

    Fantasy Tri. Some information. 40 foot trimarans take from 4000 to 8,000 hours to do well if home built. There are many people who will look at this thread who will verify that statement. An 80 foot tri would take at least 3 times as long. It takes a proffessional full production line cat builder 1500 hours to build a 40 footer cat and they have full moulds and jigs for everything. Orange 2 a 130 foot racing catamaran took over 100,000 hours to build. The lighter a tri is for a given size the more expensive and time consuming it is to build unless you are a very knowledgeable and experienced home boat builder. Yes an 80 footer can be done in ply and timber BUT it would be heavier and require additional fiberglass reinforcements in the cross arms unless the boats beam was significantly reduced to EG 14 meters. Their is no magic pudding. You can make a cheap big boat but it will not be fast. Here is what can be done on little money. Look up a boat called That Multihull Dynamics, Inc. - News Article http://www.multihulldynamics.com/news_article.asp?articleID=243 Mark Hassall had built smaller tris 30 and 37 footers and had one last build. It required logs of timber out of a jungle, second hand rigs of monohull sail boats, several helpers and 6 years and he was using a fast build technique and the boat is only 62 foot long. The boats sailed OK but could not be driven fast as the masts would have broken as they were designed for a 38 foot boat. Just moving the separate build components of this boat would take 50 people or a crane. The paint job on a boat this big is $10,000 plus using cheap paints etc. Carbon Fibre can be used by a home builder but it requires special build techniques that some times can take 5 hours to set up for a 20 minute "build" process. Look up Vacuum Bagging.
     

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    Last edited: Sep 12, 2019
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