There was an interesting exception to the rule that a sub had a lot of trouble maintaining depth at all stop. If the thermocline was enough different in temperature, there was a layer of dense cold water below a less dense layer of warm water. A submarine could set ballast to sink in the warm layer but still have enough positive buoyancy in the cold layer to sit there for a couple of days without power if they wanted to. A couple of times during the war that saved the subs' cookies, giving them the opportunity to shut everything down and affect repairs without worrying about depth-keeping or running out of battery power.
|