Tri with central hull smaller than side hulls

Discussion in 'Multihulls' started by Kuter, Dec 23, 2021.

  1. Kuter
    Joined: Dec 2021
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    Location: Kłodzko

    Kuter New Member


    my post concerns cruising multihulls.

    I've been thinking about a trimaran with its central hull smaller than its side hulls. The result would be a trimaran looking almost like a very wide catamaran. The side hulls would have dimensions (layout) of typicall catamarans' hulls so they would provide better living space but the central hull would be knife shaped - very narrow and probably shorter as well (no living space at all). The role of such narrow central hull would be to improve upwind performace etc. As a storage place the central hull may provide for example some liquid storage space. It would be really narrow.

    I don't have any experience in designing sailing vessels. My question is: does such a multihull make any sense?

    I haven't found existing trimarans or concepts like this so I'm also curious if there are any.

    Fair winds and following seas!
  2. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    You are describing a feature with wetted area but no volume -it makes no sense to me why this would improve upwind performance. What you describe reminds me of extreme high-performance catamarans that have a deep central ridge that is really just fairing for a deep kingpost. A deeper kingpost allows for a stiffer boat/weight. It is not uncommon to run the kingpost down to the waterline at rest because it will be above when heeled sailing as long as the series has a minimum wind speed for racing.
  3. BlueBell
    Joined: May 2017
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    BlueBell . . . _ _ _ . . . _ _ _

    Hi Kuter, welcome to the Forum.

    I like your idea. It's in use now in many racing boats.

    Do you have any drawings or sketches of your idea?

    DogCavalry likes this.
  4. Kuter
    Joined: Dec 2021
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    Kuter New Member

    Hi BlueBell,

    No, I don't. It's only a concept in my mind for now. Could you give me some links or names of vessels?
  5. BlueBell
    Joined: May 2017
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    BlueBell . . . _ _ _ . . . _ _ _

    Check out the Sail GP boats and the America's Cup boats.
  6. oldmulti
    Joined: May 2019
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    oldmulti Senior Member

    Kuter. This may not be exactly what you are looking for but it will give a guide. The AYRS booklet 59 "Multihull design & Catamarans 1966" Page 63 and 64 features a design called "Del Ray Tri-Cat". Go to Booklets – Amateur Yacht Research Society Scroll down to 59 and hit the download button. A PDF of the above will be delivered. The image below will not take you to the book. Also you can google the title and you will probably be able to access the PDF.

    Attached Files:

    BlueBell likes this.
  7. upchurchmr
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    upchurchmr Senior Member

    This is useless except for extreme racing boats.
  8. fallguy
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    fallguy Senior Member

    What exactly would be gained here in a regular cruiser?

  9. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    Narrow yes but only in the immersed portion. These designs are usually to accommodate a cuddy cabin or a pilothouse. It is best not to be touching the waterline to reduce drag. Variation of this design is a central hull way forward, ahead of the outboard hulls and not touching water. It acts as a shock absorver when the nose pitches.
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