Two passengers were successfully launched from a parasail vessel for a ride aloft. As they were being winched in the winds picked up, and the parasail towline winch became inoperable and 800 feet of towline payed out stranding the passengers aloft. Additionally, the vessel was unable to make way through the water while battling rough seas and the strong winds, the U.S. Coast Guard said in a safety alert derived from a recent parasail casualty investigation. The cause of the winch malfunction was due to overheating of the hydraulic power system which occurred because of an inadequate oil cooling system (through hull fittings / scoop type system) that relied solely on the vessel's movement through the water.