How bout this..? ?
This has a name but I forgot it.
Starboard Side Sheet
Point A: connect a block with becket on the aft gunnel deck cleat. (use soft shackel)
Point B: mount two Double blocks (total four sheaves) to underside of boom at or near aft end.
Point C: Mount a
double Ratchet block forward on underside of boom. located forward on the boom where ever you like. Or mounted using a track so it is movable.
Next:
Connect sheet to the becket at Point A. Eye splice here would be good.
Run sheet through sheave at Point B and back to Point A
Run sheet through sheave at Point A and back through block at Point B
Run sheet forward along boom to point C
Bring sheet tail down through Point C. This is the starboard working tail.
Port Side Sheet:
Above is for ONLY ONE SIDE. So repeat the above for the other side -- utilizing the remaining Double block at Point B and double block at .Point C
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The above configuration meets Hunter216's wish to utilize the existing aft deck cleats:
BUT.. I think that makes the connection points (POINTs A) too far apart. Perhaps a better location for POINT A is an Eye Strap mounted on the top or side of the seat.
View attachment 169560
This is the same
concept as the mainsheet system I had on a 40' Leapord Cat. It took no time at all to learn having separate mainsheets for Starboard trim and Port trim. This can give you the same motion as a traveler -but without a traveler. You use the active sheet for trim angle - the lazy sheet for leech tension/sail shape.
If the mainsheet tails dangling from the boom are offensive, you could run the sheets forward to the mast, then turn them back to the cockpit. You could even use a cuddy-top ST Winch there, I suppose.