Self-Righting / Rightable Trimaran

Discussion in 'Multihulls' started by Doug Lord, Mar 21, 2011.

  1. Doug Lord
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    Doug Lord Flight Ready

    I just discovered this:

    "At the Gougeon shop construction also started on Flicka, another plywood cruising trimaran. Jan spent four long days on the capsized Flicka in the Atlantic Ocean during a qualifier for the next OSTAR challenge. He had plenty of time to think about rightable trimaran designs before a passing freighter rescued him. Flicka had to be abandoned at sea.

    In 1980 Jan designed and began to build Splinter, a developed plywood trimaran designed to be rightable after an offshore capsize. Splinter was the second boat, after Adagio, the Brothers launched with a wingmast. She is now owned and raced by Bob Struble (father of A-Cat and DN champ Matt Struble) in Saginaw Bay competes against Adagio and another noteworthy Gougeon built boat, Ollie."


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    I didn't know that the Gougeons had designed rightable trimarans-is anybody familiar with these boats or how the righting system worked?
    Also, I'm doing as much research as possible on "self-righting" trimarans should one exist. I'm doing a model now* to test my own concept and would appreciate any leads on other proven systems.

    * http://www.boatdesign.net/forums/mu...-self-righting-trimaran-test-model-36058.html
    Thanks, Doug
     
  2. Corley
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    Corley epoxy coated

    You might like to search up Len Surtees re: self righting trimarans. He has one available as a stock plan personally I don't agree with "smart keels" on multihulls as it's extra parasitic weight but he is a huge believer maybe they are ok on cruising boat.
     
  3. Doug Lord
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    Doug Lord Flight Ready

    ==============
    Thanks , Corley I appreciate it. Never heard of "smart keels".
    I am , though, 100% convinced that a keel is not ,necessarily, bad on a multihull-even a high performance one. If you consider, say, an 18' tri designed to have two 175lb. crew sit in the center cockpit with 20' beam and loads of SA( about 267 sq.ft.) then take one of those crew and put "it" on the bottom of the daggerboard you still have a very high performance little singlehander. I think the possible uses of ballast for high speed little tris that could safely be sailed by disabled or physically restricted people have been dramatically underestimated. I think its possible to use innovative design to come up with a self-righting tri and I'm going to find out.
    Don't discount ballast completely.......
    Thanks,again.
     
  4. Doug Lord
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    Doug Lord Flight Ready

    Self-righting Trimaran

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    I just read about Len Surtees-quite a talented guy. Seems that his self-righting tri idea was one that you yourSELF right-not one the automatically rights as per a "self-righting keelboat".
    I'm hoping to find any info about designers that have created a truly self-righting(automatically) trimaran.
    --
    Maybe I missed it but I didn't find Surtees mention of a "smart keel"-any links?
    I'll look some more....
     
  5. catsketcher
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    catsketcher Senior Member

    Get the old book - the Capsize Bugaboo published by Multihulls mag. It has a few self righting designs in it.

    I think that they often need compromises in capsize prevention to make it work though.

    cheers

    Phil
     
  6. Doug Lord
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    Doug Lord Flight Ready

    Thanks, Phil.
     
  7. Gary Baigent
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    Gary Baigent Senior Member

    Splinter is Jan Gougeon's great looking little trimaran (whereas Splinter and Ollie look a bit boxy/clunky to my eye) and Splinter's rigging stays are block and tackle with the high block maybe a couple of metres up. The mast is a wing and the main hull is flush decked and guessing, Jan designed the boat so that the buoyant wing mast would halt the platform going much past 100 degrees - then the rigging would be slackened/tightened so the platform came upright; then the mast would be winched vertical again. Doesn't look like a self righting design; such a beast would be as rare as rocking horse defecation. Horrible Misty Miller would be one but the keeled cat has bad trade offs: double keel weight and draggy buoyancy bag at mast top. Splinter looks almost square beam to length so the boat has to be a powerful performer, unlike MM. There is a neat photograph of Splinter in the Gougeons' book.
     
  8. DaveJ
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    DaveJ Senior Member

    I don't know if this helps, But Ian Farrier does talk about righting his tri's on his web page.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    ========
    Thanks, Dave-I'll check it out...
     
  10. luckystrike
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    luckystrike Power Kraut

  11. Doug Lord
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    Doug Lord Flight Ready

    Self-righting Trimaran

    ==============
    Thanks, Michel. That looks like a good righting system. But it is another one of those that claim "self-righting" for a system that requires the crew to take action to right themselves. It isn't "self-righting" in the sense that term has been used most of my lifetime meaning "rights itself automatically with no crew intervention". I wonder if they use the term in that way as a marketing ploy?
     
  12. catsketcher
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    catsketcher Senior Member

    different ways of capsizing

    Doug one of the methods in the Bugaboo book relies on the floats being submersible and the boat going over sideways. It seems to me that this is a little bit cute as the mechanism could not work if the boat went over its nose.

    This method is probably more useful for older narrow tris. As tris got wider pitchpoling became a more common way of falling over. Splinter is one of these go over sideways tris. She would probably not self right from a pitchpole.

    I think this is a bit like the quest for the holy grail and without trying to be disrespectful, probably as futile. The huge flurry of re-righting ideas propounded in the 70s and 80s died out when the boats stopped capsizing as much. Monos need self righting because they can get laid over even in a nice day by a bunch of gorillas with too big a kite up. Then everyone giggles as the boat pulls up and sails away. As multis are so stable they don't often capsize, therefore they don't need to self right.

    cheers

    Phil
     
  13. Doug Lord
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    Doug Lord Flight Ready

    Self-righting Trimaran

    ============
    Phil, I don't agree- at least for the time being. My interest is not in cruising tri's or in tri's over 20'. I'm interested in seeing if it is possible to design a small , relatively high powered trimaran that will self right automatically. I want to find all the info I can on schemes that have been tried to create a self-righting tri-not one you right by yourself. I am not adverse to using a ballast keel because it will not significantly slow the boat if the weight can be kept within the range of the weight of one person or a bit more.
    I think it can be done- I'll probably know more from my own testing in a while.
    Thanks for the info....

    PS- I do agree that any real "self-righting" system must work from a pitchpole or capsize. The type of boat I'm considering is far more likely to pitchpole than capsize....
     
  14. catsketcher
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    catsketcher Senior Member

    Okay then Doug here are my quick ideas

    You have to include a wing mast, maybe even some kind of thickened inflatable head to the main like kitesurfers have. Say it is there to stop tip vortices - get it to do something else as well.

    Then inverted buoyancy will be the killer. Upside down is stable with normal boats. So maybe some trick where the back half of the float and main hull will fill up with water and the big wing mast pulls itself up to the surface. Then you need a very cleverly thought out amount of buoyancy low in the floats and main hull to clear the water out.

    The floats could look like normal floats but just have a watertight self bailing floor - just self bailing. Of course they would have a normal deck for normal sailing but they would bleed water if needed. The cockpit in the main hull will do the same. The mast and main have to overcome this floor buoyancy and then the floor buoyancy has to rotate the platform from nose up in the air to flat. Mast rake, flotation and CB and CG are all very tricky.

    In terms of energy you have to make the upright state a lower energy state than upside down. That will be hard.

    have fun

    Phil
     

  15. Doug Lord
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    Doug Lord Flight Ready

    Thanks, Phil. I think on an 18 footer with buoyancy at the masthead and a sealed mast you don't have to consider the upside down case(for self righting). The boat would be nearly vertical-with the mast close to parallel to the water post pitchpole. The dihedral of the cross arms could be such that the buoyancy of the ama bow would actually become RM. The ama+ crossarm buoyancy would be just a bit less than the total weight of the boat: in the unlikely event that the boat were to capsize-it would be only momentarily because the buoyancy of the whole ama+ cross arms would be acting to right the boat along with the keel ballast. The pitchpole case is more difficult which is why I'm building a test model.
    That, coupled with the keel may do the trick. The system would rely on the rigs' integrity post pitchpole/capsize. My interest is in a self-righting system from a capsize or pitchpole of 90 to about 110 degrees only. I have no interest in a system that "self-rights" from a turtled position. The design I'm interested in would not be able to turtle in the conditions in which it would be designed to be used.
     
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