self righting motor trimaran

Discussion in 'Boat Design' started by jonr, Jan 1, 2010.

  1. jonr
    Joined: Sep 2008
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    jonr Senior Member

    Catamarans and trimarans have some advantages, but I wouldn't want to roll over in one - very likely that it would remain upside down.

    What if the center hull were free to rotate in the roll direction? Ie, it would be weighted such that it would always orient itself to be right side up, even if the outer hulls were upside down (assume they are sealed and symmetrical so it doesn't matter). There would be a swivel at the bow and stern of the center hull that would allow it to roll 360 degrees wrt the outer hulls.

    Could it work? Has anything similar been done?
     
  2. Luckless
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    Luckless Senior Member

    Isn't one of the points of a wide body multi hull like a Cat or Trimaran that it is harder to flip in the first place?

    It sounds complex and is a major system that could be prone to failure.

    I think a safer design would be one that is intended to stay afloat when flipped. If you want a manually controlled self-righting function built in for half way clam weather (as in you can survive in the upturned craft till the storm passes) then a water ballasting system may be your best bet. Basically a series of controllable ballast tanks that you start flooding at one end or the other of the boat till it stands up right in the water, then over balance it and start empty the tanks.

    You have to remember to consider the structure of the craft when it comes to righting. Most multihulls, from what I have read, are best flipped end over end because it reduces the chance of structural damage. However there is one unmanned Trimaran I came across a few months ago that is designed to flood one ama till it sits on its side, then flood a tank in the bottom of the other ama while emptying the top ballast tanks on the flooded side.


    I personally vote for the "Just don't get yourself in position to flip it in the first place" option. It isn't the safest option, but I like it better than wondering if the rotation rig is going to fail and I find my boat doing funky things.
     
  3. apex1

    apex1 Guest

    The headline is a contradiction in itself already!

    Multies do┬┤nt self right, they are cuffins!
     
  4. Stefan H
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    Stefan H Junior Member

    Good idea! I think it could work if the center hull had round sections fore and aft with grooves. The crossbeams would have rings similar as giant ballbearings around the central hull. It would not work for a sailing trimaran though since the mast would get stuck...but for a motor trimaran, why not?

    However, a motor trimaran with ballasted center hull dont need the floats in the first place...or maybe as a sundeck?
     
  5. apex1

    apex1 Guest

    A mono would need less thoughts and provide more safety................
     
  6. Stefan H
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    Stefan H Junior Member

    Apex, what a creative idea...a mono. It is a design forum, new ideas should be encouraged.
     
  7. apex1

    apex1 Guest

    After some three cicumnav.s and about half a dozen of newbuilts (for my personal use) I would claim to have at least a idea how a boat could look like.
    another idea how a good boat could look like.

    But no idea how it could look like a multihull! Not when given for free and all expenses paid for 50 years, I would sail a multi for more than a afternoon trip in sheltered waters,

    They are coffins! Fast moving coffins! No experienced sailor ever sails a coffin.
     
  8. Luckless
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    Luckless Senior Member

    So, if they are so dangerous, and all experienced sailors would never sail on one,... Then why are they still being made and experimented with? And used by experienced sailors?

    Do you have any data to back up the idea that they are 'coffins'? Statistics to show that they are actually more dangerous, and analysis on why they are more dangerous? After all multihulls have been used in the pacific regions for how many hundreds of years?

    Are modern super fast sailing races really any more dangerous in Mono vs Multi configurations?
     
  9. Doug Lord
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    Doug Lord Flight Ready

    =======================

    Thats among the most ridiculous comments I've yet seen on this forum.
     
  10. apex1

    apex1 Guest

    You see, one can learn every day................
     
  11. apex1

    apex1 Guest

    That is a wide spread lie! The native outriggers have NOTHING in common with a contemporary multihull!

    Sail them, and you know what I mean.


    A multi is a fast sailing coffin period!

    And every racing event involving these coffins prooves how much I am right, and you are wrong!
     
  12. Typhoon
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    Typhoon Senior Member

    WHy not have one outrigger you can fill with water, then blow down with air?
    Theory goes, when capsized, fill one hull then when vessel is at around 90 degrees, blow water out and it rights.
    Of course, you'd need a small lever or something to start the airborne hull in the right direction, but the forces wouldn't be great.
    Tri's are particularly hard to capsize when you don't have sail loads acting on them......

    Regards, Andrew.
     
  13. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    From: http://docs.hydrofoils.org/vallejo.pdf

    Conclusions
    Inherent advantages of multi-hull ships in the deck area, speed/power performance,
    seaworthiness, and safety
    can provide reliable fast passenger transportation in regions characterized
    by high sea states and austere harbors. New concepts, such as small water-plane area ships with
    outriggers and wave-piercing trimarans with aerodynamic unloading, can offer a step change in the
    capabilities of marine vehicles and are economically more efficient than contemporary ships.
    ========
     
  14. apex1

    apex1 Guest

    Yes I agree CAN.
     

  15. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Andrew, some flotation in the mast could assist. There is a trimaran that does right itself, a link to a video was posted a while ago. It looked like it worked pretty well.

    Come now Richard, we're not opening the mono vs multi thread again and not here. Next you'll want to ban all sailboats and only talk steamers.

    Besides, mono's spill more beer than any other boat and my wife won't get on half a boat :D

    My opinion is capsizing on a multi is not even an issue if you sail it within safe limits. Only in racing where the limits are pushed then may be. Other than that they seem to be some of the safest boats around.

    No, you won't convince me otherwise.
     
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