RedactedNarrative: Vessel 1 had a tarp over the stern; the Operator removed the tarp, opened the engine cover, and did not smell fuel at this time.  The Operator waited 3-4 minutes before starting the motor, then closed the engine cover and backed Vessel 1 out of the slip.  Vessel 1 then travelled approximately 100 feet before exploding.  No injuries were suffered as a result of the accident, however the ventilation pipe of Vessel 1 was reported to have been on fire and Vessel 1 suffered heavy damage to the fiberglass throughout the vessel.