Sonar

The system to raise and lower the sonar dome

Sonarman Trade Badge

Water temperature can bend sonar waves. Submarines hides under thermal layer. The solution was Variable Depth Sonar VDS shown below.

Variable Depth Sonar System on the stern of a DDE

Aircraft, Sea King Helicopters, Grumman Tracker aircraft and long range Argus and Orion aircraft used sonobuoys

A passive sonobuoy. Basically a floating transmitter and a hydrophone attached to a long cable

There was an  other sonobouy system that I don’t recall ever seeing in operation. It was an active sonar transducer  housed within a sonobouy. That system was called “Julie” named after a stripper familiar to the development team, because she “made passive Bouys go active.” Honestly I haven’t made this stuff up.