Built-in tank lockers should be located above the static waterline. The lid should open from the top, and the hatch must be gasketed and capable of being securely latched. Ideally, the lid should open directly to the atmosphere; however, if that's not possible-if, for instance, the L.P.G. locker is located in a lazarette-then its lid should be as close to the hatch opening as possible. The locker's vent and drain must be installed at the lowest part of the locker; they mustn't trap water, and the drain must be, again, 20 or more inches from any opening, and it, too, must be located above the static waterline. The locker should be used to stow only gas. Spare tanks must be stored in the same fashion as those being used, which means that they may not be kept in sail lockers, the lazarette, or the cabin.