by kahle67 » Mon Apr 24, 2006 12:22 am
Just thinking out loud but the only problem in the theory above is that the slot should be measured in the direction of the air flow, not across the deck. Therefore, your slot adjusments are of course your jib sheet and topping lift.
In the real world, an overlap of the main and jib is desirable to help the air flow over the top of the jib connect with the air coming around the leeward side of the main. Obviously, with a self tacking jib on a boom, an overlap is not possible and in light air, you really don't want the leech of the jib dragging across the front of the mast anyway.
I think the main reason some might have more space between the jib and the mast is the topping lift. The jib booms are sometimes longer than needed (for proper sail set) to accomodate the topping lift. Remember, the leach of the jib is not a straight line, there is some roach, so the sail needs to clear the TL when tacking. Also, the closer the topping lift runs to the mast, the more likely you are to have it get caught on the spreaders due to improper rig tension or elastic failure.
After measuring one of my rigs, the clew of the jib is around 2" from the mast (as Carl suggests in his tunning guide)which leaves the upper portion of the leach at max roach right around 1/2". I can live with that, but once again the positioning had nothing to do with the slot, it is because of my topping lift configuration.
Reichard Kahle
Charleston, SC
Oops! Where is spell check when you need it?