One of my father's friends [back in the 1950's] had a surplus PT Boat [Plywood hull, built in Oyster Bay NY]

Originally it had 4 Packard copies of the Rolls Royce Merlin engine, driving two shafts.

He made some serious modifications, ultimately to three shafts. The original transmissions and props were modified to work with a pair of marine diesel engines, and one Packard was retained with a new transmission and prop shaft [forward only] to provide just enough oomph to get the hull up onto the step. [Much lighter than the wartime fuel and ammo load]