Convoys' Passive Sonar (detection range)

[Azgrim]

Hello, everyone.
I've read lots of tutorials and threads about convoy approach tactics, googled my eyes out, but still couldn't find an answer on this one:

My passive sonar picked a convoy. I've estimated their course and speed and figured out that I should round this convoy to make an ambush further on their course. So I should hit Ahead Full or at least Standard to have a speed advantage.

Now here's what puzzles me:
If I can hear the convoy, can they hear me as I'm steaming for interception?

What is the range of DDs passive sonar? Or maybe other warships?

Any enlightment on the matter would be much appreciated.

[fireftr18]

If you can hear them, they can hear you. When I have to do an end around before radar, I get out of sonar range and parallel the course, then get back in range on occasion to check progress.

[Crannogman]

I cannot recall ever being detected by passive sonar while surfaced. But it is likely mod-dependent

[Azgrim]

Originally Posted by Crannogman

I cannot recall ever being detected by passive sonar while surfaced. But it is likely mod-dependent

Well me neither. The convoys don't even change the course or speed as long as they don't have a visual on me while i'm surfaced.

[Crannogman]

Originally Posted by Azgrim

Well me neither. The convoys don't even change the course or speed as long as they don't have a visual on me while i'm surfaced.

Once you visually ID a ship, its map marker will have arcs that represent its various sensors' ranges. Hydrophone is usually represented as a fairly short-ranged arc that excludes the 45degrees astern. That said, their hydrophones seem to be able to hear at least 1000y.

In answer to your original question, you generally hear them a lot farther away than they hear you, and a surfaced run to intercept should not be detected if you stay outside visual range

[nionios]

Originally Posted by Crannogman

I cannot recall ever being detected by passive sonar while surfaced. But it is likely mod-dependent

So when in heavy fog, it's better to stay surfaced than submerged in order to approach a convoy? In those conditions the visibility is a few hundred yards...

[Crannogman]

Originally Posted by nionios

So when in heavy fog, it's better to stay surfaced than submerged in order to approach a convoy? In those conditions the visibility is a few hundred yards...

I wrote a patrol log recently about a convoy drive-by, in which I approached a convoy in heavy fog and rain. The ships began zig-zagging and the escort ran at me long before I was able to make visual contact, but I didn't start receiving gunfire until about 700y. I don't know quite how they detected me at ~3500y, but (since they weren't shooting) I suspect it was by radar or hydrophone. I believe I was at decks awash

[Armistead]

They cannot pick you up on the surface with sonar.

As far as submerge, mods do vary what settings they use for each sonar, however numerous other values come into play, mostly weather, but also running silent, under the thermal, etc. With active sonar, the profile of your sub has great impact.

As far as your crew, they will only call out sonar contacts within the range of type of sonar, but a game flaw is you can always hear contacts from the start of the war once they enter the zone. Simply, even if your crew doesn't respond or you don't, once a group enters in the zone, the limits of the best equipment available the entire war, the game spawns the group. If you pay attention you'll notice game lag when the game spawns a group in the zone, larger the group, the more the lag. You can take advantage of the by going to sonar and listening yourself as you aren't limited.

Only danger you'll have on the surface is radar, which you'll notice when a escort comes at you fast. Some later escorts and DD's have radar later war, so you'll see some in some convoys. Obvious, attacking on the service in a storm with fog, you can't see. I usually with the APR see what ship has radar if any and start at the end of the convoy he isn't on. Almost ways they try to run up behind you. If a large group, I'll get to about 600 yards and shoot the deckgun or 40's by bearing out of site. Usually u start a fire or a light blinker comes on making it a easy target in the fog. Be careful getting too close, you sink a ship loaded with fuel or ammo, the blast range can reach out and damage you or even blow you up. If a radar ship gets within 2000 yards I'll got to radar depth, usually they go back to their station, then pop up and go back at it again, sometimes dodging in and out between ships using them to block. It's rather easy to take out a complete convoy on the surface in a storm.

[nionios]

Fortunately, by the time you can get APR, there are few Japanese ships equipped with radar.