I have a 1:16 downhaul with two blocks at the sail, doubling the standard 1:8 system. The whistle was audible more downwind and on a reach (i.e. when the boat was fast), and downwind we used no downhaul, so I suppose it's not from the downhaul. There's this saying "Only a silent boat is a fast boat" that worries me, the sound I like a lot <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />