Sonar fundamentals

[I'm goin' down]

I understand how to turn the sonar on. It makes a ping. There is another device next to it with a handle. What the heck is that? What does it do? What does sonar do, and what are these contraptions supposed to tell me?

[Zero Niner]

That handle turns the hydrophone, which is a passive listening device.
Turning the handle turns the hydrophone, allowing the operator to pick up screw sounds from whichever direction it's pointing at. The green light will light up when sound is picked up.
That way, a sub can 'listen' for contacts (via the sounds the ship's propeller makes as it rotates in the water) and get the relative bearing. However no distance information is obtained, although in game one can get a rough idea from the hydrophone line drawn on the map.

[Sailor Steve]

At the hydrophone station you can actually listen to the screws (propellors), and hear the different sounds that different ships make. That's pretty cool. It's also sometimes called "Passive Sonar", because it doesn't do anything but listen.

'Sonar' is an acronym for SOund NAvigation and Ranging. Active Sonar sends out a beam of ultrasonic sound, which makes the distinctive 'ping' noise you hear in the movies. When it encounters an object in the water it bounces back, and the operator hears a 'return echo'. In the movies you'll hear it go "ping.....pock", "ping...pock", ping.pock"; with the two sounds coming closer together as the target gets closer. A good sonarman can tell you the range to the target with great accuracy.

[I'm goin' down]

That really helps. Thanks.

[banjo]

Use your Home and End key to rotate the hydraphone (listening) gear.

[I'm goin' down]

on my 1941 porpoise class the sonar works. I used it too! Thank you all.

I am finally getting better and have sunk some freighters and even took out a cruiser in a convoy at long range and at night. Then I was depth charged by a destroyer. I was counter attacked so quickly that I forgot to watch torpedo impact on the cruiser or see is sink! But I got credit for the sinking!!