After a battle, Blankenburg remembers feeling relieved. Even though not all of the ships that the U.S. submarines sunk during World War II were combat-ready, feelings of culpability still did not transpire. Some of them were civilians, fishermen. The best way to remain undetected was to hide under the surface of the water. You re better off staying deep water is like the atmosphere.
Different altitudes mean different temperatures.
Since temperature changes deflect other submarines radar equipment, it was wise to stay under a couple of temperature layers. A downside to lurking beneath the surface was that the submarine could not exceed 11 knots, and even then, it could only travel at that speed for short periods of time. On the surface, the Bugara could travel double that speed, at 22 knots. In addition to a faster speed, while the Bugara was on the surface, her electric motors could be charged in case of an emergency. The Bugara was powered both by electric and diesel engines.