Technique for getting range with hydrophones

[PurpleCity]

When I play with map contacts on, my sound man appears to know the approximate range and bearing of any sound contact. He also seems to know if the contact is closing or moving away.

Is he sending an active sonar ping, or is there another technique for estimating the range?

[Soundman]

He is pretty good huh? No, he is using passive sonar. The bearing is easy, but yes, they are also pretty good at estimating range.

[PurpleCity]

Thanks.

Is this realistic, could a sound man actually estimate range just by listening to the screws? I'm assuming they're comparing amplitude and pitch against memory.

[Fish40]

I might think a skilled soundman may be able to make a pretty good guestamate as to the range of a target by listening to how far away/close the ship is. A more reasonable and accurate way would be to actively ping a target, and get the range that way. I've done this myself on several occasions. But beware!! If you use active sonar with escorts present, they can and do hear it! I make it a habit to only ping lonely merchants.

[RSColonel_131st]

In my opinion (without knowing too much about how those old hydros worked), the sound you get from the speaker/headphones is an electric current. It will be louder (more current/voltage) when it's closer, and less when it's further away. Does that sound plausible?

If so, I wonder why they didn't match the hydrophones with a pair of calibrated volt meters, going of known volume levels for near/far away merchants and warships.

[Hitman]

If so, I wonder why they didn't match the hydrophones with a pair of calibrated volt meters, going of known volume levels for near/far away merchants and warships.

They did. That's represented by the green lamp that lights when a contact is made.

Is this realistic, could a sound man actually estimate range just by listening to the screws? I'm assuming they're comparing amplitude and pitch against memory.

Well more or less yes, sound intensity obviously increased in principle when the sound source is closer BUT the sound transmission in the sea water is a real headbreaker when it comes to giving exact solutions. A good proof of it is how even today submarines can still stay unlocated if properly hidden below thermal layers and such. That means that you could hear a strong contact for a distant target if the proper sound conditions happen, and inversely not even hear a close contact.

As a 688i/Sub Command/Dangerous Waters player I have readed a lot about the matter, and the only conclusion I have comed upon is that you hardly can draw any conclussions at all , so variable and strange is the sound propagation thorugh water.