Historically, how hard was it to hear a uboat with hydrophones?

[Pillar]

I'm curious what passive sonar technology was capable of in WW2 on the destroyers and destroyer escort vessels. If a Type VII or IX was operating at slow speeds, say 3 kts, in otherwise calm conditions how close would a destroyer need to get to hear the uboat?

Does passive sonar at this time rely on human ears or do they have any kind of electronic detection of sound assisting them? How big a bonus is an electronic broadband? (Obviously, technology detecting specific frequencies, i.e., narrowband, is a huge step forward.)

Anything that can be said about passive sonar vs WW2 era submarines would be helpful and interesting, please share your thoughts and wisdom.

Thanks!

[Oneshot/Onekill]

Originally Posted by Pillar

I'm curious what passive sonar technology was capable of in WW2 on the destroyers and destroyer escort vessels. If a Type VII or IX was operating at slow speeds, say 3 kts, in otherwise calm conditions how close would a destroyer need to get to hear the uboat?

Does passive sonar at this time rely on human ears or do they have any kind of electronic detection of sound assisting them? How big a bonus is an electronic broadband? (Obviously, technology detecting specific frequencies, i.e., narrowband, is a huge step forward.)

Anything that can be said about passive sonar vs WW2 era submarines would be helpful and interesting, please share your thoughts and wisdom.

Thanks!

From what i've read, under the conditions you set forth, about 3000 meters.

Passive sonar is the technical term for LISTENING sonar. So yes it is simply listening with the human ear, thats it.
Now days, it's a bit more technical on modern submarines and ASW vessels, as they use sensors in the sonar housing that pick up vibrations which are then fed into a computer which use's a certain algarythim to identify what the vibration is.

But in WWII, that technology obviously did not exist yet.

Active sonar in WWII was your basic ASDIC. Sending out a beam of electric energy and waiting for the return. Which by doing so also gave away your own position. Now days very few submarines or ASW vessels use active sonar, because they lose their advantage of suprise by giving away their position.

[Damo]

Originally Posted by Oneshot/Onekill

Now days, it's a bit more technical on modern submarines and ASW vessels, as they use sensors in the sonar housing that pick up vibrations which are then fed into a computer which use's a certain algarythim to identify what the vibration is.

So basically, you fart, you're dead...?

[Lt.Fillipidis]

The Passive sonar depends on how good ear the sonarman has, as Oneshot/Onekill said but the detection range also depends on other factors too.
Noise that the destroyer itself produces, angle of the destroyer compared to the uboat and possible other factors.

[Jimbuna]

Give thanks it wasn't as efficient as the ingame sonar which can hear 'through' land

[comet61]

I have read here and other U-Boat websites that sonar was also directly affected by layers of different temperatures of water. Haven't thought too much on that. Not sure if SHIII is modeled for that scenario.

[SeaWolf U-57]

Originally Posted by Damo

So basically, you fart, you're dead...?

Yes and if you had been eating beans and eggs the night before it was probably at the hands of you own ship mates.

[flag4]

Originally Posted by Pillar

I'm curious what passive sonar technology was capable of in WW2 on the destroyers and destroyer escort vessels. If a Type VII or IX was operating at slow speeds, say 3 kts, in otherwise calm conditions how close would a destroyer need to get to hear the uboat?

Does passive sonar at this time rely on human ears or do they have any kind of electronic detection of sound assisting them? How big a bonus is an electronic broadband? (Obviously, technology detecting specific frequencies, i.e., narrowband, is a huge step forward.)

Anything that can be said about passive sonar vs WW2 era submarines would be helpful and interesting, please share your thoughts and wisdom.

Thanks!

dont know much 'bout sonar but found this on wiki http://en.wikipedia.org/wiki/Sonar

also Ducimus did an excellent post with pics of this coz i have it printed off but cant find the thread. Date: 01.24.2007: 05:43 it is entitled GWX's "uber" AI demystified.
maybe its on record still somewhere. one of the moderators maybe able to dig it out.......over to you Jim!