What if you ran out of fuel?

The boats were very careful not to. There were no fueling stations other than our forward bases and there were few of those early in the war. There was no plan to refuel at sea. Although there is no apparent documentation of a boat running out of fuel, it would have been possible to rig something up to refuel it or even tow it to the nearest base if necessary.

Inside the boat, there were clusters of small black valves. Those were used to tell how much fuel is left in each of the fuel tanks. The result isn’t an exact number of gallons remaining, but it is a good indication if the crew had been paying attention. They always did. The least bad thing to happen if they weren’t paying attention to fuel levels, and ran out, was serious embarrassment. The worst would have been to find themselves stranded, adrift and nearly helpless in hostile territory.