How did the depth settings work?

Once the approach officer identified the target and decided at what depth he wanted the torpedoes to run, he ordered that set into the torpedoes. This would typically be 15 to 20 feet for large ships and 7 to 10 feet for smaller targets. The depth setting was actually done in the torpedo rooms. The crew there used a crank to set the desired depth on a spindle.

Control of the depth after launching was originally done with a diaphragm and pendulum arrangement. After the depth problem with the Mark 14 torpedoes was confirmed, this was changed to an Uhlan gear, or planetary gear, system. This allowed the torpedo to recover more quickly and get to the desired depth. When the torpedo sensed that it was running too deep, the elevators at the rear of the torpedo would rise to point the torpedo at more of an up angle. (Torpedoes normally ran at a small up angle to compensate for its own weight.) Conversely, if the torpedo sensed it was too shallow, the elevators would lower so the weapon would run deeper.