Answer: sponson

AnswerCrossword Clue
SPONSONCanoe's air chamber.
SPONSONDestroyer's gun platform
SPONSONProjecting gun platform on a warship
sponsona projection from the side of a ship
sponsonstructure projecting from the side or main deck of a vessel to support a gun or the outer edge of a paddle box
sponsonbuoyant appendage at the gunwale of a canoe to resist capsizing
sponsonprotuberance at the side of a flying-boat hull, designed to increase lateral stability in the water