How long did it take a US fleet submarine running on the surface to recharge its battery fully for maximum duration submergence?
I realize that the answer depends on how many engines were being used for recharging, versus propulsion — I imagine that in a really tight situation that anticipated an imminent need for long submergence, all four diesels would be thrown into recharging, as fast as possible.
In Edward L. Beach's novel Run Silent, Run Deep, at one point the protagonist/narrator Lt. Cmdr. Richardson indicates that with two of his four engines recharging the battery, every 10 minutes gives them another hour of submergence, if that becomes necessary. But 10 minutes for an hour submerged running time, even at only 2 knots, seems very optimistic. Or am I wrong?