RedactedNarrative: Vessel 1 was having engine trouble and being operated back to the ramp under the power of a small trolling motor. There were many boats on the small lake which resulted in choppy water. Operator of vessel 1 turned his vessel which caused waves to come over the stern. He tried to hook up his bilge pump but could not do so quickly enough, and the vessel swamped, capsized, and sunk. Operator was OK and the vessel was towed back to shore and removed from the water.