Extending mast head fitting rearwards to allow wider sail to clear back stay.

Discussion in 'Sailboats' started by DennisRB, Feb 21, 2010.

  1. DennisRB
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    DennisRB Senior Member

    How do mono hulls usually get away with running square top or wider main sails? We tired to pull a beach cat up a trailer sailer mast and the sail is too wide towards the top and hits the rear stay.

    I have seen some mast heads with a rearward facing extension that allows the back stay to join further aft. Has anyone got any pics or info on this?
  2. TeddyDiver
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    TeddyDiver Gollywobbler

  3. DennisRB
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    DennisRB Senior Member

    Thanks. Used google image search but couldn't find much.
  4. The copper guy
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    The copper guy Junior Member

    Also look at Bahamas, There local race boats all have that fitting
    Just google race week in?
  5. Doug Lord
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    Doug Lord Flight Ready

    I was faced with that problem on a 16 footer I built. It had a tall narrow jib and I assumed I'd need a backstay to keep the forestay tight enough. I used a straight carbon tube to extend the backstay as far aft as possible which tended to bend the top of the mast too much. It turned out that a powerfull vang+ mainsheet was enough on this boat.
    Also take a look at the Melges 24 arrangement-click on the image for a clear illustration of the system:

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  6. powerabout
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    powerabout Senior Member

    A Mumm 30 also has a large fibreglass 'flicker' similar to the M24
  7. messabout
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    messabout Senior Member

    The horizontal thing at the masthead is sometimes called a mast crane. It solves one problem but introduces others like eccentric mast loading. If the mast is designed for use with a crane then all is well. Attaching a crane to an existing mast could be problematic because the mast will bend in places that the sailmaker did not contemplate.
  8. Brent Swain
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    Brent Swain Member

    It puts a forward bending load on your mast.
  9. capt vimes
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    capt vimes Senior Member

    why not just avoiding all the headache with a mastcrane and simply exchanging the aftstay with 2 running backstays...??
  10. The copper guy
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    The copper guy Junior Member

    If when it is don, You ever get a new mainsail? The sail maker can use a wider curved head board this will give you a lot more sail area and increase boat speed,
    Keep her bum clean
  11. ned
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    ned Junior Member

    i'd go for twin top mast back stays . i sail on a 30ft cainting keeler and thats what we use.
  12. DennisRB
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    DennisRB Senior Member

    Thanks guys. I missed most of these replies since I didn't get notifications for some reason. The whole point was that the trailer sailer did have a ripped main requiring a new one. I thought if I made a "mast crane" I could get a better sail made. Its too late now and the boat is sold, however I am still interested in this.

    When I was sailing out in the bay a fast racing type mono of about 30' sailed past me in the opposite direction. It had what looked like a large main with a lot of area at the top. I didn't get a good look but he had twin back stays of coloured rope (spectra?) The windward stay looked tight, and the leeward stay looked very loose. Does this sort of set up require that you adjust the back stays on each tack? Would you need to loosen the says just so the sail can get past on a tack? If so wouldn't this be dangerous to the integrity of the rigging in a jibe? I cant see how having 2 back stays would allow that much of a size increase of the head of the main without similar fouling problems compared to a single stay.
  13. Stumble
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    Stumble Senior Member


    We call them kickers around here. Basically all you need is an old batten and a small block. Secure the batten to the top of the mast with the projection haft, and run the backstay through the block. Then attach the block to the end of the batton. As you tack the batten provides enough lifting force to backstay to clear it over the mainsail, but is flexible enough to lay down when you crank on the backstay.

    if you really have the backstay on you might have to ease it through the tacks, but I doubt it unless you radically alter the size of the sail (There is a Melgus 30 here named Tiberon that has a 6' roach that has to do this).

    Cheap, simple, and it works.
  14. alan white
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    alan white Senior Member

    The windage of a crane big enough to do the job might approach the same windage of a mast extension----in other words, why not raise the masthead height in order to use the jibstay to counteract the backstay, which would then terminate at the masthead with a normal small crane? the mast is only in compression. The crane is a lever, and so its wind shadow is far greater per unit of length. It also needs a corresponding jib crane lever, another chunk of windage.
    The jibstay would be longer, true, but potentially higher aspect too.

  15. Typhoon
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    Typhoon Senior Member

    Google up Australian 12ft skiffs.
    If the main is built correctly, the sail itself and it's sheet loads will allow the mast to be supported and you will have gust response, that is, the head of the sail will twist off automatically to depower the rig.
    12ft skiffs run permanent side/backstays and conventional shrouds to the forestay as you"d find on a typical sailing dinghy with no backstay.
    There is no ned for a backstay, use vang and sheet/traveller to adjust mast tension. 12ft skiffs run big assymetric masthead spinnakers too, so if they don't lose a mast, it must work.
    A very good friend of mine worked on pioneering this rig and making the main work, I was working for him at teh time, so know a bit about it.

    Regards, Andrew.

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