Trimaran with accomodation in the amas

Discussion in 'Multihulls' started by eiasu, Nov 23, 2012.

  1. eiasu
    Joined: Nov 2011
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    eiasu Junior Member

    Yes Oceancruiser, that's true, I remember I read this on Hughes' website.

    Another number that is strange for me is the weight of the Pahi 63,
    on Wharram's website I read 8ton, quite light no?

    Just another numbers of a beautiful large cat from Chris White,
    Atlantic 77
    Length / Displacement (m/ton) 0,7960247859
    Sail Area / Displacement (sqm / ton) 9,9194033865
    Length overall: 23,47 m
    Displacement: 29,48 ton
    Sail Area Upwind 292 sqm

    Ciao
    Eiasu
     
  2. El_Guero

    El_Guero Previous Member

    ROFL!


    I think Richard Woods should receive 'first right of refusal.'

    ROFL! ROOM for TWELVE .... is now room for thirty ....


    This one was beautiful ....[​IMG]

    I think what you want is a long cat with narrow hulls and a center 'hull' which almost touches the water. Giving the appearance of a trimaran while keeping the much better performance character of the cat.

    Now it is time to go from general skepticism to small scale modeling ....

    Overall length will still be about 108' (33 meters) producing shallow draft and increased speed for a larger number of total accommodations.

    I am thinking 4 king sized cabins. 6 queen sized. And 6 cabins with 2 pairs of bunks, yielding 24 single accommodations and 10 double for a total of 34 passengers. And 6 or 8 crew berths. Running two masts would allow 3 primary crew for manning the ship. And 3 for galley, scuba instruction, piloting the yacht tenders, etc. And still allow you two additional crew for special purpose uses.
     
  3. cavalier mk2
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    cavalier mk2 Senior Member

    The Pahi 63 isn't burdened with the weight of a large deck superstructure allowing the light weight and good performance #'s.
     
  4. eiasu
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    eiasu Junior Member

    This I would like to understand: "the much better performance character of the cat"
    better then a trimaran?

    Unlikely for all kind of EU rules we don't want to go beyond 24 meters,
    for the accomodations that could be an idea in the pic:
    a mix of atlantic77 and the Avatar of Crowtler
     

    Attached Files:

  5. Richard Woods
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    Richard Woods Woods Designs

    Some years ago I drew a 70ft catamaran for use as a sailing research vessel in the Indian Ocean and east African coast.

    It had a saloon-meeting area-conference room about 20ft square. Bunks for 20 scientists plus 6 crew. Plus of course diver changing rooms (with compressors) space for an small robot submarine and microlight seaplane

    The hulls were big enough for there to be standing headroom under the bridgedeck in the hulls. So the bridgedeck was taken out to the full width and bunks were fitted under the saloon

    It was a huge boat, designed as a work boat, not to impress people on the dockside, nor for regular charters which tend to be couples based (and thus most charter boats have double bunks everywhere and ensuite cabins)

    Maybe something like that would suit?

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  6. El_Guero

    El_Guero Previous Member

    Eisu,

    Richard can explain it better than I, I think he told me the reason originally.

    Each hull produces a 'shock' wave like an airplane would. These waves interact with other waves. Those waves produced by other hulls interact with each other.

    When the hulls are within a distance equal to about the length of the hull, there is what amounts to a parasitic drag between the hulls.

    At the distance between hulls in catamarans and trimarans, this parasitic drag is 'about' 20% for each hull.

    Like I said, Richard can explain it much better.

    And I think if you look aver what he has produced, you will find he not only can produce what works, he can produce what looks 'sexy.'

    Someday, I will get to meet him. But, that won't be anytime soon.

    Regardless of 'EU' rules, to do what you want and rent the ship out, you will need to make compromises.

    Either you will compromise when all your family shows up (most likely), or you will need a longer ship. 30 berths competitive with other upscale catamarans is gonna take some really goos design work to get it all to fit.

    Seriously. It will require someone like Richard who has a history of making the correct design choices to make small fit like it is big.

    Discuss his use of 'chines' with him. He has done this to get small catamarans and trimarans in the 16 foot length to carry a cabin and even bunks for people. I think. Our discussion was some time ago.

    He has been answering questions for you. And he is one of the top designers - that is my opinion reading up on him on the web.

    Just my 2 cents worth. Small change, yes. But, I think he can do what you want to be done.

    And he won't mislead you. If ugly works and beauty doesn't, he will tell you. If beauty will work as well as ugly, he will tell you.

    I think you will get much more done discussing your needs with an expert in the field.

    wayne
     
  7. rberrey
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    rberrey Senior Member

    You will have to add berth for a crew as well. Rick
     
  8. rberrey
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    rberrey Senior Member

    I think for the space you want you will need the Horstman trimaran concept. There will be more than one deck on a boat that size, and you can design the interrior to fit your needs. Use of the wings make more space not pay load capability. For a boat that size you can find a NA to design you a tri that makes use of ama and wing space. I,m sure Richard Woods would be willing to start designing big tris if asked. Rick
     
  9. cavalier mk2
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    cavalier mk2 Senior Member

    I thought Richard was suggesting Nigel Irens in a alternate identity post....The pros need to be paid to tri to come up with something. Even a study costs money. For a cat I'd send them to Barry Choy, though Richard's commercial design does sound sensible. There are a fair amount of large motor tris and ships now, even the Navy has some so 3 hulls in the water can't be all bad.
     
  10. mcarling
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    mcarling Junior Member

    I'm under the impression that Richard Woods has expressed disinterest in designing large trimarans. Please accept my apologies if I'm wrong on that (or any other) point.
     
  11. El_Guero

    El_Guero Previous Member

    Fair enough.

    But, Eiasu does not need a tri. What he has seen and thinks looks great is a tri.

    TWO different worlds there.

    He needs what works. And I think that is why Richard has moved towards the catamaran and away from trimarans for larger ships. Larger than about 15 meters.

    No matter how you design it, a large trimaran slows weigh down when you keep both amas in the water .... It will get sluggish and difficult even for a good crew. There are things to do to help with that. But, you can only override the inherent weakness of trimaran design so much.

    Even catamarans suffer from the same weakness, but with only two hulls, you can overcome enough of the weakness to gain from its strength.

    IMHO.

    At around 18 or so cabins, this will need some serious room. And that usually points towards a single or catamaran and away from a trimaran.

    wayne
     
  12. mcarling
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    mcarling Junior Member

    Sure, since the revelations about requirements, it is my opinion that accommodating 30 persons within 24 meters LOA is best accomplished in a catamaran (and I'm very much a trimaran fan). I would guess a beam of about 15 meters, one deck spanning everything, a partial deck above that, and a full-height deck within each hull. The only problem I see is that it would be quite spartan if the budget is 6M euro.
     
  13. Alex.A
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    Alex.A Senior Member

    Spartan compared to what? Hemisphere?
    6 mil is plenty for a decent 24m cat if you don't need too much bling.....
    Again - what requirements?
    Luxury hotel or Wharram make do?
     
  14. rberrey
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    rberrey Senior Member

    A large catamaran with one deck spanning everything with a partial deck above will have space in the two hulls below the deck covering everything . I would be willing to bet a large tri like an old style Cross, or Horstman, or any wing design will have as much or more space due to the center hull space adding to the 3rd deck, than the same length cat. There is more covered area bow to stern on this style tri than on most cats, horstmans are called roomarans for a reason. Rick
     

  15. Alex.A
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    Alex.A Senior Member

    And more wetted surface area.....
     
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