Comparison of sonic and supersonic listening
Since enemy ships make sonic and supersonic sounds, both types of gear
are necessary for efficient listening. Each has its own particular advantages
one is incomplete without the other.
Sonic gear is useful for picking up targets at great distances
because sonic sounds travel farther. Also, on the JP gear sounds
appear more natural and are more easily recognized. Therefore,
you can identify not only the machinery noises of enemy ships,
but also any telltale noises your own submarine is making.
Supersonic gear is useful for picking up the important supersonic noises that sonic cannot get. Supersonic gear is especially
superior for catching the bursts of supersonic sound used by
enemy escort vessels in searching for our submarines. (In addition, QB and QC gear can be used to send out sounds into the
water to determine the range of an enemy ship.)
The WCA Installation
The WCA Installation on a submarine includes all the sonar gear that
handles supersonic sounds. Much of this equipment is grouped in the conning
tower, where it is known as the "WCA Stack." To locate all the various units,
let us subdivide WCA into its two main parts:
QB Gear has its receiver-amplifier and remote-control unit in
the conning tower. The projector is mounted on the starboard
shaft and extends just below the keel under the forward torpedo
room. The electric training mechanism for turning the projector
is in the forward torpedo room.
JK/QC Gear also has its receiver-amplifier and remote-control
unit in the conning tower, and its training mechanism in the forward torpedo room. The double-faced projector extends just below
the keel on the port side, opposite the QB projector. A range indicator, used with either QB or QC, is also part of the WCA stack
in the conning tower.
NOTE: The WCA Installation also includes NM gear (in the control
room), which is used for determining the depth of the water beneath the keel.