ASA and PSIA Instructor
Join Date: Apr 2000
Thanked 38 Times in 38 Posts
Rep Power: 18
The main largely serves to affect the angle at which the boat sits to the wind...partially trimmed and you sit close, eased out and you sit broadly..except if the main is trimmed in close it is likely to overpower the jib and tack the boat (regardless of rudder angle).
Certified...in several regards...