TAMUmpower wrote:
Would it really pull aft on the foot more? Wouldn't the traveler car position be the only thing that can change the pull on the foot? If I left the car in the same position then I could see moving the hole changing the foot tension but it seems like the leech is the only thing it would be changing.
I think for a mainsail, you're right about the outhaul being the primary factor in foot tension. On a jib, however, changing the hole on the clew plate changes the angle of the jib sheet, and therefore the angle of the force you're putting on the sail. Pulling down more = tighter leech, pulling aft more = tighter foot, looser leech.
Like mmiller said, on an H18, clew plate doesn't make much difference on the main, and the jib fairlead cars are used to change the angle of the sheet rather than a clew plate. My jib just has a single grommet at the clew!