A 1982 Fourwinns inboard/outboard had left a local marina near the Susquehana River.  One hour later the operator heard a loud "pop" and saw the engine compartment rise up with flames coming out.  The operator ordered all 4 passengers to don PFDs and jump overboard.  The vessel sank as it burned to the waterline but no one was injured.  The operator admitted he did not vent when they started the engine.
Havre de Grace