In the simplest of terms, an AC generator supplies power directly to a 120-volt circuit to run AC accessories throughout a boat, as well as charge the boat’s batteries (through an AC-to-­DC charger).

The U.S. Navy has awarded UQM Technologies Inc. of Frederick, Colo., a $70,000 contract to design a compact, lightweight, diesel-driven generator for small unmanned military boats, the company said ...