All of the Moorings boats we've been on had the Y-valves zip-tied in the overboard position, and our last Horizon charter did as well. I think of this often when swimming in mooring fields. Blech. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Sick.gif" alt="" />

Edit: correction: when we first started chartering with them the tanks were usable, then that seemed to change later on.