I actually found the solution for that. Now air effects the sails.
But the other problem is that no matter how I play with nConstrains attributes I can't manage to keep the sails hanged to the the hooks. They resist air only to a very low strength level, then they detach an fall. But I need more than that in order to design strong air effect in my entire movie.
Hey! I do understand your problem, you only need to group your cloth with the rest of the object so that when you apply the air field it will affect and move the whole thing, just pick your cloth and the other stuff then press ctrl +g for windows or command +g for mac
I hope it works... good luck. =)