To get the fast sail, you need to go to Windfall Island at night, and participate in the auction. It takes place in one of the buildings on the right, in the path past the arch. The thing is, everytime you do the auction, you can't be certain that it'll be the fast sail thats up for sale. So you just have to keep doing it. And if your at the tower of the guards, you should NOT have 15 hearts, the