Are Japanese destoyers too good at detecting your sub??

[groomsie]

Originally Posted by Rockin Robbins

Now, just because they are pinging you, that doesn't mean they know where you are. Yes they automatically will ping you every time, but no, that doesn't mean they detect you and will react to your presence. Plenty of times in TMO I have just ignored a pinging destroyer and snuck right by or right away. Patience is your friend. Flinch and hit the jets at the wrong time and they'll detect you for sure. Be very slow and deliberate about your decision-making.

Thanks RR. Yep, I've done same and in fact last night in the end the escorts were pinging away and dropping cans as I crept away until I got...blessed silence.

BTW, last night was the first I've experienced a k-gun attack, took me by surprise.

[tater]

In RL, the IJN pinged too much. Many times they lead US to their targets since they'd drive around banging away with the active sonar.

[Steeltrap]

Originally Posted by tater

In RL, the IJN pinged too much. Many times they lead US to their targets since they'd drive around banging away with the active sonar.

Fact is low frequency sounds travel much further in water than high frequency ones, so the sounds of merchants pounding away at 7-10kts would, realistically, be much more evident than some pings being fired off in comparitively tight cones. They would only generate a return echo out to a few thousand yards at most (the more advanced ASDIC models had ranges of around 2,500 yards, and they were far more effective than Jap stuff).

I'm aware of many instances of ships being detected by sound out to many miles, but not aware of many instances of many escorts being detected outside those ranges due to pinging.

Mind you, USA's radar would detect ships at huge ranges later in the war, so they were better off on the surface in most respects. I found it very interesting to read just how little time Dick O'Kane spent submerged when patrolling - his default was to be on the surface from what I've read in Clear the Bridge.

[doulos05]

Originally Posted by Steeltrap

Fact is low frequency sounds travel much further in water than high frequency ones, so the sounds of merchants pounding away at 7-10kts would, realistically, be much more evident than some pings being fired off in comparitively tight cones. They would only generate a return echo out to a few thousand yards at most (the more advanced ASDIC models had ranges of around 2,500 yards, and they were far more effective than Jap stuff).

Mind you, USA's radar would detect ships at huge ranges later in the war, so they were better off on the surface in most respects. I found it very interesting to read just how little time Dick O'Kane spent submerged when patrolling - his default was to be on the surface from what I've read in Clear the Bridge.

Yeah, the more you think about it, at least for me, the more it makes sense that they would just ping the hell out of the water. Besides, as an escort, their job is to protect the convoy from threats on, above, and below the water. If you can use radar (or RDF technology, which the Japs had at a much higher level than we thought at the start of the war) for surface and air threats, it only makes sense to use active sonar to protect against submerged threats.

Otherwise, you're basically sailing along blind as can be to what's going on around you. Sure, you may get lucky and hear a sub with your passives, but why not pound away with your actives as well since your already making too much noise as a convoy of 8+ ships cruising at 8-9 knots to hide. No sonarman worth his salt is going to mistake 16 propellers making rotations for 8 knots for a false transient.

And, at the point where they're close enough you can find them with active.... your passive sonar isn't going to give you nearly enough information, that sub is Danger Close and you need to be tossing enough ash cans on his head that he thinks it's the 4th of July.

Realistically speaking, convoys don't try to hide from their predators, they're trying for strength in numbers (although hiding is nice ). There's so much other sound going on in a convoy that pinging isn't going to significantly impair your OpSec, unless they're pings heard 'round the pacific.

[SteamWake]

The vast majoirty of convoys were located by airel recon.

Sailing about pinging away may have been some deterint but I dont think they intended it this way. ASDIC was kind of new technology at the time and the best way to use it was not self evident.

[Nicolas]

So then, japanese destroyers in sh4 pings all the time, (because no way they can detect if not) but why i not hear the ping until the dd is very close and detecting the submarine

[SteamWake]

Originally Posted by Nicolas

So then, japanese destroyers in sh4 pings all the time, (because no way they can detect if not) but why i not hear the ping until the dd is very close and detecting the submarine

First off you can hear the pings regarless of wether or not they have 'detected' you.

Secondly active sonar has a range after a certian distance the amplitude of the signall falls off dramatically following the inverse square law. Its sound waves not radio waves.

Game wise I think it is just a certain range if you are within the range you hear it if not well you dont.

[Nicolas]

The pings can be heard when they search, (already detected) from 1000 yards...

[SteamWake]

Originally Posted by Nicolas

The pings can be heard when they search, (already detected) from 1000 yards...

News to me... can anyone confirm this?

[Nicolas]

SteamWake, actually the ping can be heard from 1200 yards...
I dont like being detected by a game thing without reason (unless japs had ultrsonic or something)

[Rockin Robbins]

Repeat: hearing the ping says nothing about whether you were detected or not. It happens all the time that a pinging escort may not detect you at all.

[Nicolas]

I know RR, i have read your comment before, its true, i just dont like this 'magic detection' i wish it could be modded.

[doulos05]

The key to remember is they may not actually be detecting you when pinging. They're pinging away trying to detect you. You've been made when the pings suddenly start occuring closer and closer together. In that case, you may want to have a listen at the sonar station yourself and see if it sounds like he's increased speed and is closing (or press "Report nearest sound contact"). If he's increasing speed and closing, it's time to go deep.

Try to hold off your turn until after you're under the thermal layer (if there is one) then lay over hard to port or starboard (I try to turn towards the convoy) and rig for silent running. Of course, if you hear him pass right over your sub, it's time to turn regardless of depth. Take advantage of the fact he can't hear immediately in front of him, directly below him, or at any range in his baffles and lay over towards the convoy and make max speed. Once you hear the detonations, rudder amidships and silent running, continuing the dive if you haven't passed a thermal yet.

Verify your bearing relative to the convoy (using the sonar contact lines) and you may still get a shot with the stern tubes once you've passed under them (or even come up in the middle and get them with forward and aft tubes).

[Galanti]

Originally Posted by Rockin Robbins

Repeat: hearing the ping says nothing about whether you were detected or not. It happens all the time that a pinging escort may not detect you at all.

No, but in my experience, and please correct me if i'm wrong, pinging destroyers mean that they suspect there's a snake in the grass, and are taking appropriate measures.

Which unfortunately means the convoy or TF they're escorting is taking evasive action (ziggzagging and increased speed) and your attack has been effectively foiled.

[PFK]

I guess using the depthsounder is a bad idea. I was on photo recon approaching the coast. There was a destroyer stationary at 2500. Looked like it was getting shallow so I checked the depth. Suddenly the destroyer revved up and came charging over for me. I suppose its reasonable that his hydrophone could have picked up my ping