Chainplate design, material..

Discussion in 'Sailboats' started by Robin Larsson, Jun 27, 2007.

  1. Robin Larsson
    Joined: Mar 2007
    Posts: 37
    Likes: 2, Points: 0, Legacy Rep: 17
    Location: Gothenburg, Sweden

    Robin Larsson Junior Member

    Hi everyone!

    I´m building a 44feet monohull, an old Swedish Wasa 55, in a bit modernized version.
    One of the biggest changes is that I´ve gone for a different mast, the original mast is i keelstepped, two pair of straight spreaders, double lower shrouds, forestay about 2.5meters from masttop, running backstays.
    The rig I have is from a the Swedish AIE35 sportsboat, got hold of a rig only used for 5weeks of testing, the former owner thought it was a bit to stiff and heavy, so he changed down. It´s a Seldén C211 alumast.
    It will be deckstepped, two pair of swept spreaders, single lowers, no running backstays, forestay 1.3meter from the top. The boom is 30cm longer, and the upwind SA will be 66sqm instead of 55. Only selftacking jib, and gennackers.

    But, there is one problem, I bought the boat half finished, most of the GRPwork is done, andus the bulkheads and frames for attaching the original chainplates ar already in place, and rather well done I´d sail. The problem is that my new chainplates cant sit right there. On the attached pics you can see the frames for the capshrouds and aft lowers, and the forward lowers should go to the bulkhead. The mast will stand inline with the original capshroudframe.
    The new rigs chainplates(only one on each side) should sit 41cm abaft the mastcenter, thats 9cm infront of the aft frame... And about 14cm in from the hullside.y

    My idea was to build something like on many new boats, a small fitting in the deck, coupled to a point lower down, like a stringer, but only I want to cables from the fitting, one to the forward frame and one to the aft, about bench level. Was thinking of using Vectran lines instead of stainless rods.
    That feels like a good way to not having to cut away the old frames and laminating up new ones.

    What do you think of that solution? or should I move the chainplates all the way out to the hullside, and bolting a stainless fitting to the hull?
    Or maybe laminate in a "Farrierstyle" Carbonchainplate to the inside of the hull?

    If I go with my first solution, the fitting in the deck could be made atleast three ways: A stainless fitting, cut from 100*10mm steelplate, and bolted to the deck.
    A mini carbonversion, imagine a very short Farrier chainplate, about 10cm, but with the stainless tube and pin in both ends. Laminated in to the deck.

    Or, a Equiplite dyneemaloop through the deck, a alu U-profile glued to the deck and in that I fix the ends of the two Vectranlines, and the watercup:)
    Instead of a standard thimble in the dyneemaloop I could use a Precourt deadeye directly in the loop and get rid of the turnbuckles altogether.

    Which one would you prefer?

    The forestay could use the same system, it will mount 130cm in from the bow, and have to be fastned to the stem. Was thinking a stainless fitting trough the stem, which will also take the bobstay for the articulating bowsprit:), and from there I run a Vectranline to a fitting in the deck. There is a bulkhead about 20cm abaft the forestay.

    Some more info on the boat, the hull is pretty thick chopped glassmat/polyester balsasandwich. The stem is something like 40-50mm massive FRP...

    Hmm, now this became a bit long, hope someone reads it all:)

    Hope for some advice here guys, how would you solve this?

    Best regards
    Robin Larsson
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