square top sail

Discussion in 'Multihulls' started by brendan gardam, Mar 16, 2020.

  1. brendan gardam
    Joined: Feb 2020
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    Location: east gippsland australia

    brendan gardam Senior Member

    Sorry to ask another dumb question...
    My mainsail has a 9mt luff. Can i get 1700mm cut off the top to make a square top sail. or is that too much?
     
  2. patzefran
    Joined: Feb 2011
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    Location: france

    patzefran patzefran

    Classic A cat with a 8.50 m luff use max 1 meter chord square top !
     
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  3. brendan gardam
    Joined: Feb 2020
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    Location: east gippsland australia

    brendan gardam Senior Member

    Thanks. I guess any more than that would be a gaff rig. I will measure my sail and see how it compares at 7.3 mt.
     
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    So you plan is to reduce sail area? Square tops are normally used to increase area
     
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  5. brendan gardam
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    brendan gardam Senior Member

    Yes gonzo. I am reducing beam on my cat.
     
  6. revintage
    Joined: Nov 2016
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    revintage Senior Member

    I actaully did the opposite and cut the lowest panel for a small dinghy for least work. Also cut the lowest panel of the A-class sail I needed to downsize as I wanted to get the best possible aspect ratio.
    But making a square top has been done before. See attached cut down plans for the first generation 49er. When making a square top from a pin top you will probably get a lot of work correcting the luff curve.
    49cut.jpg
     

    Attached Files:

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  7. brendan gardam
    Joined: Feb 2020
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    Location: east gippsland australia

    brendan gardam Senior Member

    Good work you did there. But i would lose too much area cutting the bottom off the sail. I will take it to a sailmaker to get the work done. I would not know what to do. May also price a new square top main as well. If I do this i can shorten the mast by 1500mm which will make a big difference when raising and lowering it.
     
  8. revintage
    Joined: Nov 2016
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    revintage Senior Member

    Hi Brendan,
    So the real problem is that you for some reason need to shorten your mast? If you want to cut 1,7m from the top of the mast you probably also have to move the hounds lower, cut the wires, etc, in order to make the rig work well together with the sail.
    If only size of the sail matters, you can cut how little you want from the sail foot to achieve the wanted area.
     
  9. brendan gardam
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    brendan gardam Senior Member

    its a fractional rig , 1.5 mt cutoff is above jib and spin halyards. don't have to modify anything. the whole idea is to make the mast easier to handle and reduce some of the sail area because i am reducing the beam of the boat. i am making the boat more user friendly and quick to set up at the ramp. as i sail alone the more i do to make the boat easier to ready for water the better , within reason.
     
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  10. waynemarlow
    Joined: Nov 2006
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    waynemarlow Senior Member

    Not really sure that 1.5mt cut off is really going to make much difference in mast handling. Better methods of mast handling maybe an answer, using the trapeze lines to stabilise the mast laterally and gin poles using the main sheet make even the heaviest of masts doable. I presently put up 9mtr aluminum masts on my own with a good simple setup that takes minutes to setup. Perhaps you may even want to think of purchasing a carbon mast rather than a mainsail, they do make life so much easier.

    As to your sail area, its better to have a larger sail which you can reef when needed, than to have too smaller sail when you long for a bigger sail when the wind is light for the majority of your sailing time. Have a look on the recent Everglades Challenge 2020 where it was mandatory to have reefing points and systems on relatively small boats.

    The other question to ask yourself is perhaps you may have the wrong type of boat for your needs, sometimes people forget the basics of you need to be in control of the boat rather than the boat being in control of you, downsize if that is the case.
     
  11. brendan gardam
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    brendan gardam Senior Member

    good points . but i don't want to downsize. the boat is the one i want and the modifications i am talkimg about are not hard to do and will turn ot into a much more user friendly setup. my mainsail does have reef points .
     
  12. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    How much weight are you taking out; maybe 3 kg?
     

  13. brendan gardam
    Joined: Feb 2020
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    Location: east gippsland australia

    brendan gardam Senior Member

    its a very heavy mast. i think 1.5mt will be around 10 kg.
     
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