This site hosts copies of WWII US military submarine manuals, now declassified:
Rapid search
1. From the bearing at which the hydrophone was left by the previous watch, sweep through 000 degrees and continue on to 180 degrees.2. Then, reversing direction, sweep back around the full circle to 180 degrees. If no suspicious sounds are heard, shift to …
Progressive search
Sweep forward two full turns of the handwheel and then one turn back. Continue up the same side, two turns forward and one turn back, until you have crossed the bow. Then train rapidly down the opposite side to 180 degrees. Reverse direction and train two turns forward, one back, two forward, one back, until you have crossed the bow again. Then train rapidly down the other side … and so on. Continue this procedure for the duration of your watch, unless ordered to do otherwise.
(Thanks, MrBigStuff247!)
