Cat or Tri with Lee Pod

Discussion in 'Multihulls' started by BMP, Jun 15, 2022.

  1. BMP
    Joined: Jun 2022
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    BMP Junior Member

    I have been reading a lot about proas trying to wrap my mind around the concept and many of the proponents tout certain proas' ability to avoid (to a point) capsizing and easier self recovery when they do when compared to other similar multi-hulls which seems to be a function of the lee pod (either a small flying hull or pard of the deck/house extended to leeward). My question is couldn't a cat or a Neelesk tri have a similar pod with similar righting characteristics? And if so, why arn't they used?


    Here is a good explanation of the proa lee pod function (scroll down a bit):
    Pacific Proa Company | Frequently Asked Questions (FAQ) http://www.pacificproa.com/faq.html

    And one on cats:Sailing Catamarans - Stability Part 3 https://www.sailingcatamarans.com/index.php/articles/12-to-be-published-mainly-technical/56-stability-part-3

    Both are interesting, A big thanks to the authors for taking the time write all the helpful.
    Thanks,
    Ben
     
  2. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Multihulls are more stable than the monohulls but from there to think that, in addition, they recover, more easily, the righted position after a capsize ( "easier self recovery"), there is a great distance.
     
  3. BMP
    Joined: Jun 2022
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    BMP Junior Member

    I was referring to different multi-hulls not to mono vs multi hull questions.

    Specifically could lee pods or over hanging cabins be added to cats or tris to improve righting characteristics?

    I'm thinking that since proas usually have the masts in the vaka and that the ones that self right use mast bouyancy to help with RM that the width of cats and especially tris would make it less effective. Proa at 90 deg lay a lot of the mast in the water where as with a cat the mast will not touch till well past 90 making very difficult to keep the RM positive. Pods should still help with lengthening stability curves but unless a biplane rig with very bouyant mast is used self righting seems unlikely.

    Does that seem roughly correctish?
     
  4. TANSL
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    TANSL Senior Member

    I don't think a multihull can be self righting, if that means recovering to a righted position after a capsize. It can be recovered with more or less difficulty, but self righting???
    Maybe I'm wrong, I don't know.
     
  5. BMP
    Joined: Jun 2022
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    BMP Junior Member

    You are right, I should have said self rightable. It seems that proas and perhaps other multis could right themselves from ~120 deg knockdown using mast bouyancy and lee pods, but 180 deg would require flooding a hull/ama.

    But again, could lee pods work on boats other than proas? or is that a feature unique to them?
     

  6. BMP
    Joined: Jun 2022
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    Location: PNW

    BMP Junior Member

    Here is the article that got me wondering about this, it was somewhat poorly translated but is pretty understandable:

    http://www.multihull.de/down/ndrua-gb.pdf

    He is making the case that proas and nduras are the way forward for multi-hulls but I don't see why the same design features couldn't be applied to more standard (and saleable) craft as well.
     
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