Self righting multihull?

Discussion in 'Multihulls' started by bjn, Feb 27, 2018.

  1. bjn
    Joined: Jul 2014
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    bjn Senior Member

    Hi!

    I'm starting up this thread in an attempt to learn about, and discuss self-righting multihull designs and righting aids/systems.

    Is there any production multihull which is self-righting?
    Is there any production multihull which can be singlehandedly righted after a capsize? (Small beachcats and scale models excluded)
    Which are the best aids/systems on the market?

    I have a Hobie 14 and have flipped it many times, both to its side (110 degrees), and completely upside down (180 degrees). For me (175cm, 65kg) it is quite exhausting to right it myself, especially in heavy weather, where it can easily get caught by the wind and rotate 270 degrees around centerline, so I have to start over again. And without the trapeze harness on me, or if it had a slightly larger beam, I wouldn't be able to do it. I can imagine the fear after flipping a large catamaran in the middle of the ocean.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    I think the use of a ballast keel on a "normal" multi or multifoiler is probably underrated. After seeing how Hugh Welbourns Quant 23 works with a ballast keel I was convinced that ballast could work on a foiling multihull. Might cost a little topend speed but a 20'(or so) foiling multi with ballast could still be designed to take off in light air--and be self-righting.
    It's a matter of careful design and building but it will work. It goes against the grain with some people like the first foiling keelboat does, but so what?
     
  3. bjn
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    bjn Senior Member

    If we leave lifting hydrofoils, experimental monohulls, and unproven design dreams aside for a moment (we can discuss those later), which self-righting or singlehandedly-righteable multihulls are sailing on the oceans?

    Would it be possible to go from 180 to 110 degrees by winching a floating object (fender for example) up (well, down) the mast?

    How to go from 110 degrees to upright on a boat where your own weight is just a small fraction of the boat?

    Are there any multihulls on the oceans with a ballasted keel? Wouldn't that add a significant amount of surface area and drag, due to the keel itself, and the larger wetted surface?
    Which would demand an increase of sail area, which would then demand a larger keel... and so on.
     
  4. UpOnStands
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    UpOnStands Senior Member

    the best preventative aids appear to be fear of dying, fear of drowning, fear of capsizing.
     
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  5. alan craig
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    alan craig Senior Member

  6. Doug Lord
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    Doug Lord Flight Ready

    =========================
    Thats why I mentioned the Quant 23-a well proven production boat thats been sailing since 2015 and is the first foiling keelboat in the history of mankind. There are lessons there..........
     
  7. BlueBell
    Joined: May 2017
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    BlueBell Ahhhhh...

    Doesn't Hobie make buoyant bulbs for their mast tops?
    Easy, effective solution.
     
  8. Angélique
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    Angélique aka Angel (only by name)


    ‘‘ Development, Design and Construction of the G-32 Sailboat. - This article was contributed by Meade Gougeon, Gougeon Brothers, Inc. ’’





     
    Last edited: Feb 27, 2018
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  9. Angélique
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    Angélique aka Angel (only by name)

     
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  10. Doug Lord
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    Doug Lord Flight Ready

    Great stuff Angelique-thanks!
     
  11. hump101
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    hump101 Senior Member

    Harvey Bowden had a setup to self right the Firebird Orion with masthead buoyancy and shroud release. Someone in the comments to that video has written that they have a similar system on a Reynolds 21, so looks like a viable system. You might want a self-inflating masthead float so you aren't lugging around the windage of a permanent float on the top of the mast, and you would also need to make sure that the mast could support the boat on its side in waves (most rigs on boats above about 10m length aren't strong enough to cope with the shock loads the water applies).
     
  12. UpOnStands
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    UpOnStands Senior Member

    Quick question. Assume a 40 foot cruising cat flips in heavy weather offshore. The wind is 30-40 knots and waves are 2 meters same direction as the wind. The boat is 110 degrees and the mast is holding
    The wind and waves will push the boat keel first or mast first?
     
  13. bjn
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    bjn Senior Member

    Nice, looked like an simple and effective system.

    Does it have to be a bouyant masthead, or could it be a sealed and floating mast?
     
  14. hump101
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    hump101 Senior Member

    Depends on the boat, but typically in anything other than a beach boat size, the volume of the mast alone won't be enough to hold the boat up unless the mast is a really large section sealed wing. In any case, to submerge enough of the mast to resist the overturning moment leads to a greater angle of static heel, and hence more energy required to right the boat.
     

  15. hump101
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    hump101 Senior Member

    If the centre of wind drag is nearer to the hull than the centre of water drag, then keel first (this is typical) otherwise it will be the other way around. Waves don't apply much motive force to the hull in that configuration unless they are breaking. If they are, then the equilibrium position will depend on relative drag from wind and water combined, and their locations, and would likely not be stable, i.e. the boat would rotate depending on how and when it is being struck by the waves.
     
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