Not entirely aircraft related but the there was a further prototype before the Commercial Jetfoil. When I was a member of the Boeing Seahorses SCUBA Club, we were shown the production line for the PHM (Patrol Hydrofoil Missile) boats at Renton. Just outside was a ChrisCraft cabin cruiser with an APU mounted on the aft deck to drive the water jet pumps and foils under the hull. As a Boeing club, we could technically obtain any surplus item but when we asked we were told it was already claimed by one of the Directors.