Seagull Striker angle

Discussion in 'Multihulls' started by bax, Aug 27, 2009.

  1. bax
    Joined: Feb 2007
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    Location: Massachusetts

    bax Junior Member

    In the process of designing a seagull striker for my 9m Woods cat, I have noticed that as best as I can tell, virtually all I have looked at are vertical and not slanted aft at all. I would think slanted aft as far as possible to more closely line up with the headstay while allowing sufficient room for a furled headsail would be optimal. Is there a good reason not to take that approach? (The configuration I am going for is the typical two posts joined at the top and spread apart at the bottom to allow for a low-mounted furler.)

    bax
     
  2. catsketcher
    Joined: Mar 2006
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    Location: Australia

    catsketcher Senior Member

    Gday Bax

    Quite a few cats have their strikers raked aft a bit. This can be a bit of a squeeze with anchors and furlers and it is probably a little easier to walk around on a foredeck where the striker is vertical. If you have a catwalk up front then this will take the slight vector pulling the beam aft but you should probably have a catwalk anyway.

    Interestingly this force will be less then the force from a tight forward net. I have known of a guy (whose boat had no catwalk) who pulled his nets really tight. Once they were finished they had pulled the forebeam into a banana that was really easy to see. With your (approx) 5m wide nets with lets say 5cm cells, that gives 100 tie downs at the back of the net, say you heave on each tie with 20kg of force - that is 2 tonnes of force evenly distributed along the beam. If your forestay takes a boat displacement - 3 tonnes and the angle to vertical is 20 degrees then the vector backwards will only be about 1000kg - about a third of the net force.

    I remember listening to one of the builders of Playstation. He said that they glued it all together and then worked out that the nets would have kept it all together anyway.

    cheers

    Phil Thompson
     
  3. bax
    Joined: Feb 2007
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    Location: Massachusetts

    bax Junior Member

    Seagull Stiker Angle

    Hi Phil,

    Thanks for the advice. I have been toying with the idea of whether or not to have a catwalk, and I think you have put me over the edge. One more thing to build! But it is most certainly the way to go. Your points about helping to overcome the aft vector from the headstay and the pull of the net are very good indeed. In light of that, I suppose it is more simple to just make the striker plumb.

    Now to decide if I want to split the nets in half and add a bunch of attachment points on the catwalk, or run the net over or under it. That will keep me busy for a while!

    Thanks,

    Lincoln Baxter
     

  4. jamez
    Joined: Feb 2007
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    Location: Auckland, New Zealand

    jamez Senior Member

    I have a catwalk on my Wharram and wouldn't be without it. The net is slung under it, which is the one thing I'd change in favour of a split net.
     
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