Square top mains?

Discussion in 'Sailboats' started by kenwstr, Dec 6, 2005.

  1. tspeer
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    tspeer Senior Member

    I'm not sure if you're talking about the vertical or horizontal CE. I suspect you can stand a little higher CE with the square top because it will twist off more as the wind picks up. As for the horizontal CE, I think you have to be prepared to adjust the balance once you see how it works out.
    I don't see why they'd be any worse than vertical battens, except that they are closer to the luff.
    You'll have to determine that based on how the cloth stretches and the battens bend. I wouldn't expect to get the sail right the first time. You may end up having the batten pockets taken off and rearranged.
    I don't think you have any choice if you're going to support the square-top.
     
  2. edvb
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    edvb Junior Member

    Thanks Tom

    I guess the last question is is it better for the battens to key off the mast even if it is a angle of 10 to 30 degrees or do you think it does not matter much?


    Hey, if it was horizontal there is enough data to support it so to speak. Ha Ha

    [​IMG]
     
  3. Munter
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    Munter Amateur

    edvb - they are going to be some very long battens. The middle one in particular is around 2/3rds of the mast height. Do they really need to go all the way to the luff or could the roach be supported with somewhat shorter battens?
     
  4. edvb
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    edvb Junior Member

    Munter

    I had played with the Hobie Bravo rig and found the 3/16" round battens held the sail shape yet were flexible enough not to alter the shape. Some of those were over 12' long. The longest one on mine would be about 16'. It is like a RAF windsurfer sail without the camber inducers. The battens are so light and thin that I was not worried about the weight. With the full length battens installed and tensioned slightly just the slightest wind would fill the sail and the battens would bend in one direction stiffening and supporting the leech helping give it the shape needed for the light air work.

    It is a different approach but seems to work well.

    I thought by keying three battens off the mast and two off the foot would be a good balance for sail shape reefed or not.


    Those are some of the reasons I thought it might work well.

    There are many of you that have more skill and experience to give ideas that can help with the design before final layout and cutting of the sail.

    Thanks for any input on this.

    With the five battens the whole sail is supported.

    The three on top being closer together would support the roach better where it is needed the most.
     
  5. brian eiland
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    brian eiland Senior Member

  6. edvb
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    edvb Junior Member

    Brian

    That is very interesting.

    After all the years tweaking my Raptor I ended up with the following.

    I made changes in the length and stiffness of the carbon mast with the final length being 19'. The original was 18' went up to 22' but ended up with 19' being the most balanced for oveall sailing performance and ease.

    The sail went through a lot of changes and recuts to end up what I have pictured now. It is funny how after all the changes I ended up with the five battens as shown on the original sketch.

    It is very well balanced at any reefing point and has good sail shape.

    [​IMG]

    [​IMG]

    The stays were removed as they did not help much after beefing up the mast. They just got in the way when reefing.
    [​IMG]
     
  7. Perm Stress
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    Perm Stress Senior Member

    How this sail is reefed?
    Battens as they are seen in the pictures would prevent any form of reefing.
     
  8. rapscallion
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    rapscallion Senior Member

    that boat looks like a lot of fun! Did a raptor ever compete in the everglades challenge?
     
  9. edvb
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    edvb Junior Member

    Perm Stress

    Here is a video so you can see the reefing. The current configuration is much more easy to do.

    http://www.youtube.com/watch?v=gHR7mg5LBz0
     
  10. edvb
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    edvb Junior Member

    Hi Chris

    No. The husband and wife team had trouble on one of the two boats and both decided to drop out.

    Mark just had too much sail area and had rudder problems so he dropped out after checkpoint #1

    There was one other guy that just did the race to checkpoint #1.

    My boat is highly beefed up with the active water ballast so it is different than the original concept. Here is
    a picture of draining a full tank of ballast in the ama. That is the lowest the ama will sink with a full tank.

    [​IMG]

    It does not affect handling but does slow the boat a bit if the wind strength is too low for the amount of ballast in the tank. It is the same as your Gougeon 32 when you sailed it but just on a smaller scale with pumps for both fill and drain instead of drain only. The pickup sits lower and has a streamlined fairing. No flaps and scuppers to worry about.
    It also can be manually filled or drained by removing the tank level/port cover on top of the Ama

    [​IMG]


    This was before removing the foil as it was no longer needed and was slower that the ballast system
    [​IMG]


    I believe it would have no problem completing the race. As you can see it even has a backup steering system with a rudder lock for a poor man's autopilot.

    [​IMG]
     
  11. Perm Stress
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    Perm Stress Senior Member

    Do you use "folding" battens?
    I mean battens from two metal tapes, shaped like tape measures?
    They are used for in-mast furling mains to make traditional short horizontal battens possible.
     
  12. edvb
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    edvb Junior Member

    Perm Stress

    No they are 3/16" pultruded fiberglass rods similar to what a Hobie Islander has for their sails. It roller furls very easy. The hard part was batten placement to get good sail shape and when have it furled to the sizes most needed the batten would not hang out or be in such a way to affect that. The shape is even better that the video shows as I have made improvements along the way.
     
  13. Perm Stress
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    Perm Stress Senior Member

    :confused:

    I would never think it could be possible.

    :confused:
     
  14. edvb
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    edvb Junior Member

    It looks just like a barber Pole when furled. The battens do not bend much as they are going around the mast pretty much straight up.

    Get a thin dowel or plastic rod and wrap it around a 2" diameter tube and you will see how it works. The max angle is critical I think 20- 25 degrees max. The way the sail furls the battens get more vertical before getting rolled up.

    Here is a video of a Hobie Bravo to get a better idea how fast you can furl.

    http://www.youtube.com/watch?v=0BGHJvDKL8s
     

  15. Perm Stress
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    Perm Stress Senior Member

    Yes, it is all quite understandable (and obvious, when you see it done), but takes quite a bit of lateral thinking to go in that direction :).
    congratulations
     
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