an inflatable catamaran which may be constructed principally of plastic sheet stock and plastic tubing and be easily assembled for use and disassembled for storage and shipping . a catamaran with inflatable pontoons having fore and aft pockets on each side thereof and spreader members with depending ends spaced laterally for inserting into the pontoon pockets joining the pontoons and spreader members in a rectangular catamaran configuration . a deck may be formed between the spreader members , and mast and keel are attached to one spreader member and a rudder to the other spreader member .