Anti Capsize / Damage and Sails

Discussion in 'Multihulls' started by Fanie, Dec 8, 2007.

  1. GTO
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    GTO Senior Member

    I have a 16' sharpie and originally sailed it without a boomed mainsail, or jib boom for that matter. Even with sheets loose, the flapping sails created a great deal of heeling force in higher winds. When I added booms to the main and jib, releasing the sheets depowers them nearly completely. For a small recreational sailboat, I would not have boomless sails.

    This effect may not be a problem for a cat. Just my experience.
     
  2. tuks
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    tuks Junior Member

  3. Fanie
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    Fanie Fanie

    That's it Tuks, only your cleat lets the line out so the rudder doesn't get damaged. Same idea with the round rotating cleat... if the sail gets hooked onto a hard piece of wind the rope could give same way a fishing reel would.
     
  4. masalai
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    masalai masalai

    Tucs, I like the graphic but in the bounce of a seaway and experiencing a lift/knock could prematurely release the sheet. then you would be in deeper ****/ er water. OK for the rudder blade as it would partially lift, and in a mono-hull, induce a natural tendency to point to windward (on a balanced rig).

    Not on sheets! What is wrong with having the tail loosely in your hand or over your knees, so that with a flick it can be freed off. Remember KISS!
     
    Last edited: Dec 10, 2007
  5. tuks
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    tuks Junior Member

    I fully agree, the capsize risk is one of the things that has stopped the domination of sailing by multihulls. Alot of really smart people have tried to solve this problem, and if it was as simple as an automatically releasing cleat every multihull would have one. The fact that they have been developed and dropped by multihull sailors suggests that the problem is more complex.

    I think the common solution in cruising multihulls where rigging is spec'ed to fail before the boat goes over might be the best solution.

    Unless, Fanie is a bit windgat, this should not be a problem.:D
     
  6. masalai
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    masalai masalai

    Ahhhh, It's not the cat that is unstable, just the mono sailers who try to get it to lean "just a little bit more". Cats fly best when mast is near vertical.

    I have seen recent converts sailing with all canvas up in winds they would be down to a storm jib and shitting themselves in a mono. Probably thinking something like "No sweat so far, goes very fast and hasn't started to lean yet - - - OOps over we go"
     
  7. Petros
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    Petros Senior Member

    A sheet release would not help most multi-hull capsizes. The forward part of those skinny hulls bury themselves in a swell, the thrust of the sail plus the forward momentum coupled with the sudden drag increase causes the multi-hulls to pitch pole forward. This is the most common type of capsize on a multi-hull. There is almost no counteracting force after the forward hulls are buried since there is not much flotation up front, unlike a mono-hull (though they can pitch pole capsize as well, it is less common).

    There is no additional load on the sail, so a sheet release would not get triggered.

    The only thing that might prevent this kind of capsize would perhaps be a wing-like foil on the top of both hulls, if the hulls go below the surface these these little wings will generate a lot of up-lift at the bows. You would still slow down in a hurry, but it might help keep the mast pointing skyward. Likely the crew would also get thrown forward as well, hopefully not overboard.

    Now that I think of it, these little wings on the top of each bow might be worth a try. By keeping the bows from burying in a wave, it might also help keep you from losing as much speed.
     
  8. tuks
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    tuks Junior Member

    Petros that sounds like a good idea. I recall them on some local monos many years ago, Thunderchild, a 50footer in Cape Town, and Zulu Dawn, Anthony Stewards TLC 19, spring to mind. Does anyone know if they were common on boats of that era? I see that they have since been removed from Thunderchild.

    [​IMG]
    You can just see them on this picture.
     
  9. masalai
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    masalai masalai

    Petros when was the last one and how often. Not heresay, documented please. Aside from kids having fun in the surf with a beach/surf cat.
     
  10. Petros
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    Petros Senior Member

    I do not know where you would find a statistic like that, it happens all the time. If you talk to anyone who has raced cats you would know what I am taking about. You might also search the archives of the catsailer.com mailing list you will see how common this is. Below are a few pics I found on the web, not of cats, but you can see they were running downwind with spinnakers flying.

    I had this almost happen while racing cats in a very large regatta. We were flying a hull in large chop and we buried the lee bow, we slowed down in a hurry. I thought we were going over, but luckily we did did not. Not once did I ever experience almost rolling a cat the other way (which is not true of small mono-hulls).

    [​IMG]

    [​IMG]
     
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  11. masalai
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    masalai masalai

    So far all monos, so where does the condemnation of cats come in? I wouldn't consider the "dingy" as they fly and have tenderness from other influences as well.

    That larger blue yacht is a "ball-tearer" and deserves a point. Thanks
     
  12. Alan M.
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    Alan M. Senior Member

    Pitch-poling is a function of speed, which is why cats are more likely to do it than mono's.

    Better hull designs, with more bouyancy in the bows and less rocker, are reducing the likelyhood of it though.
     
  13. tuks
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    tuks Junior Member

    If pics will help I have many

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    When Silk II(Corrected) Pitch Poled(Pink Spinnaker) I heard it was because there was alot of water in the boat.
     
    Last edited: Dec 12, 2007
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  14. Pericles
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    Pericles Senior Member

    Nice pictures. Increasing forward volume in catamaran hulls, in a similar manner to the Carolina Flare on Jarrett Bay beauties might be worth exploring.

    http://www.jarrettbay.com/home/index.php

    Pericles
     

  15. Fanie
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    Fanie Fanie

    Te-he... I like the way the guys are hanging in the rigging :D

    Tuks, looking at those pics it seems too big a main sail and too small a jib to keep the hull noses in the air (flying) instead of the rudders... I get the impression the main sails are pushing the rig into the water, then as drag becomes more than the sail pressure the sail wants to overtake the rig. The problem is not the hulls

    It seems a tilt switch in a rig like that to let some sails out is needed. A release function with my round cleat would have saved all those crafts from rolling ;)

    Imagine an oversize jib instead... the front of the rig would be lifted out the water and you may lose some bearing that could be corrected, but the rudders should stay in the water. Alsmost like these kites the lunies fly/sail with.

    That also proves it then - tha sailor is not always quick enough or in a position to save the rig from going out of control. Had these rigs had a revolving cleat that would let line out under a certain set tention this may well have saved the rigs from capsizing (and ruined the pics for that matter :D)

    The harder the hulls pushes in the water the more drag (instead of more speed) and the higher the force on the sails, letting the sail out when reaching a certain force should/could prevent this.

    Still, the problem is not the hulls, it's the sails.
     
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