Never tell the flight crew of a 57 or 67 that the slot effect does not exsist! For the wing (horizontal sail) to achieve the same amount of lift at slower (landing/take off) speeds, the leading edge slats/ slots (jib)'accelerates' the air mass thereby further increasing the P differential.

This may sound silly, but if one pinches the end of a hose, does not the water come out faster?

I know, it's confusing the heck out of me... I think I'll take Pete's approach and ignore it all... And for somebody (me) who forgot to put the bungs in the back of their boat last night and almost sank, perhaps it's all a bit premature... Not only that, I lost my wallet and left my wife's car boot open all evening in the rain... Given that she hates the sails in her car anyway, she was not amused... Boy am I taking some stick down the club...

I sailed a Laser there for a year-ish in about 1990. I was the guy who turned with a limited edition Timex Laser bought straight from the Worlds and everybody thought I was a professional... until I hit the water

Regards,
Colin

From Whidden, 'The Art and Science of Sails',

"Addressing the big picture, a correctly trimmed headsail slows the wind in the slot just the proper amount, so the air on the lee side of the main does not separate when it is trimmed at a tight angle. A correctly trimmed main places the jib in a lift, meaning the boat can be pointed closer to the wind without the jib luffing. A correctly trimmed main also speeds up the leech velocities of the jib, making it a much more effective sail. This speeding up of the flow and the fact that the Kutta requirements are satisfied in a high speed flow region mean that flow around the jib is less likely to separate. Again, the theme of sail trim is to avoid separation."

Whidden does a good job of expanding Gentry's explanation of sail theory and interaction and the gist of it all is in the quote above. I recommend the book in general as a good read for those who may not already be familiar with it.

Chris