As a sonar operator, you will have a most important job. On a patrol in
enemy waters the lives of your shipmates may be in your hands.
You must know your gear and what it can do. You must be able to recognize and interpret the sounds that you hear. You must be able to operate the
controls the way you drive a car - automatically without thinking.
Most of these things you cannot learn from books. Only long hours of
practice on the gear itself will make you proficient. There is, however, a certain amount of background knowledge which will prepare you to make the
most of your practice time.
This manual supplies that background knowledge. It is all solid meat.
You can well afford to know every bit of it by heart. Study it thoroughly from
cover to cover.
The manuscript for this publication was prepared by Columbia University Division
of War Research, at the U. S. Navy Underwater Sound Laboratory, Fort Trumbull, New
London, Connecticut. Illustrations were prepared by the U. S. Naval Training Aids Development Center.