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63904Re: Single Gaff Halyards

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  • adventures_in_astrophotography
    Jul 9, 2010
      OK, Bruce,

      > (In my mind's eye I can imagine the forces.) The sail cloth is
      > pulling on the gaff. The peak halyard is lifting up on the gaff.
      > OK. But also, the luff leading edge of the sail is pulling down with
      > force of the vang. Probably, the critical element is whether there is
      > enough force to keep that luff edge tight. If the gaff gets long,
      > and/or horizontal, the luff edge will sag unless a throat halyard is
      > added to keep the leading edge of the sail taught.

      I'm following you, but the halyard I have in mind, like those shown on the Mackinac boat, has two attachment points on the gaff at the nominal throat and peak locations. The line is routed from the truck block to a block at the throat, then to another sheave at the truck block, and then to the peak attachment point. Theoretically, once all slack is taken out of the hoist (the leading edge of a gaff sail, but I think it would be called the luff on a lug), the peak should continue to lift as the halyard is hauled on, until all slack is gone from the leech.

      I'm still pondering Patrick's point about mast height. In a perfect system, the single halyard I've described "should" work with any resaonable height above the gaff jaws, but it also seems intuitive that more height would give better leverage and the arrangement would set better.

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