The fair winds section of your sail is 75%. That means the wind is only against you 25% of the time. When its against you, you use a technique called tacking. Sail as close to the wind as you can get for a nice leg and then turn 90 degrees and catch the wind on the other side. You zig zag back and forth. Even when you calculate sides and the hypotenuse its always faster than paddling in the longboat, faster than paddling at wind speed greater than 1 in the raft, and faster than paddling in the karve at wind speed 3 or greater.