Abstract: The device of the present invention, an enclosure for partially submerged boat keels, rudders and lower units, is a box-like structure constructed to enclose those described parts extending downwards from the hull of a boat when the boat is lifted from the water on a hoist in such a manner as to prevent direct contact with the water. The device is positioned about the submerged portion of the keel, rudder or lower unit and then emptied of water, resulting in flotation of the upper portions of the enclosure to a level above the surrounding waterline. By thus preventing continuous direct contact with water during periods of storage, the adverse effects of bottom growth and gelcoat blistering are reduced or eliminated, thus enhancing performance underway and reducing maintenance.