Encounter with an uber DD

[meduza]

I was passing through the Bay of Biscay, starting my new patrol. I was at 25m traveling at 2kt, ready to go to Schnorkel depth and resupply with fresh air, when my SO reported sound contact.

It was a destroyer, some 16km away on port bow. I didn't panick, because I had such an encounter so many times before without any problem.

The destroyer was on my port stern quarter when she drastically changed course, straight towards us. The distance was some 12-13km and I knew they can't detect me. As a precaution, I ordered silent running and went deeper.

Soon, the sounds of the pinging and depth-charging disturbed the water. Our stern was hit, and damage reports started coming. Heavy flooding, starboard electric engine destroyed... We started to sink fast, stern first, while the repair crews fought the flood.

At 250m the hull started to give way to the pressure. The lights flickered madly. The boat finaly stabilized at 285m and slowly started to rise. Momentarely unconcern of the DD, I ordered flank ahead to reach the safer depths while the hull still holds.

I brought the boat to 200m, the hull withstood the torture, but destroyer is still above, pinging and throwing cans. The saga continues...

How the hell did they manage to detect me from such a distance? :hmm:

[GoldenRivet]

you mentioned the snorkel.

were you using the snorkel at the time when he made the drastic turn toward you?

whats the year?

[Task Force]

1943 or later, he had a snorkel.

[GoldenRivet]

should have guessed that

so obviously the escorts had radar... so, if the snorkel was protruding from the surface of the water it is probably what gave him away.

[meduza]

No, I wasn't using schnorkel, I was 25 m below the surface. The year is 1944, April.

What's the range of the Allies' hydrophones at this time? I know that a few months earlier was no more than 7-8km :hmm:?

The bastards are still above me, I'm unable to shake them off... and I'm running out of air, both fresh and compressed...

You may have run into Johnny Walkers units.
:hmm:
I think that's correct.

If so, it's an elite unit based on fact.
Best of luck Mate!!

[meduza]

Thank you mate, I'm gonna need all the luck in the world! Maybe Johnny Walker himself is aboard this vessel.

I tried shooting her with a homing torpedo, but I miserably missed, and got another hole in the nose. I'm gonna wait untill she spends her ammo, and try to sink her, because my evading tactic is obviously not working.
At this depth I can dodge the depth charges, but it's getting hard to breathe. It's been more than 30 hours since we took some fresh air.

[Steeltrap]

At any sort of speed the passive detection array of a DD is next to useless. The fact is the overwhelming majority of sub hunting by escorts relied on active means (sonar/asdic).
The best active system had a range of about 4,000yds max (and I think it may well have been less than that).
The best radar could detect a periscope at maybe 4,000yds.

All these would be subject to weather - the heavier the seas, the worse the sensor performance for surface vessels. It would also be affected by operator skill and 'luck' i.e. a periscope might be able to be detected by radar, but that assumes the sweep passed over when the scope was raised - with doctrine calling for periscope exposures of fewer than 5 seconds, that's a very lucky combination for the escort (or unlucky for the sub).

I'm not sure it's included in the sim, but depth charges disturbed the water so badly that there would usually be up to 1 minute in which no detection was likely - the turbulence etc played hell with active systems (lots of 'false' returns etc).

[bookworm_020]

Are you sure that Bernard wasn't banging the pots together in the stern torpedo room???:hmm:

Stay deep for as long as you can and then have a shot at giving him one down the throat. Do you have any homing / patten torps left???

[Sailor Steve]

Originally Posted by Steeltrap

At any sort of speed the passive detection array of a DD is next to useless. The fact is the overwhelming majority of sub hunting by escorts relied on active means (sonar/asdic).

At speeds over 12 knots early in the war, and 18 toward the end, even active sonar is a no-go. It projects a high-frequency beam, but it's still limited to the speed of sound and subject to disruptions from the turbulence around the hull.

[Kipparikalle]

Just go to periscope depth and sink the bastard, just stay away from its direct front, hedgehogs are quite tickling I must admit

[meduza]

I finaly got rid of Johnny Walker. :rotfl:

After 7 hours of relentless depth-charging, destroyer spent the ammo. I went to periscope depth, she politely exposed her broadside, and I used the opportunity. Fired 4 torpedoes, 20 degrees spread, 2 of which found their target. The destroyer went down.

Originally Posted by bookworm_020

Are you sure that Bernard wasn't banging the pots together in the stern torpedo room???:hmm:

If I find out that this was Bernard's doing, I'll have him keelhauled.
Seriously folks, can anyone give me a rough estimate of the elite destroyers' detection range in 1944/45?

[predavolk]

Cold (i.e., not aware of you) = about 800-1000M
Hot (searching for you) = 1500M
Pinging = 2000M at best

The BIG problem with late war sonar is that weather and depth are no longer obstacles. So unless you have a XXI and can creep out quickly at silent speed, it's virtually impossible to avoid them. The few examples I've heard seem to have happened when luck lets you creep far in one direction AND the destroyer makes a bad run in the opposite direction, giving you enough time to make a gap.

Decoys work, but only in a very narrow band. You have to place them between you and the escort. I use them in one of two ways:

1- Let the sucker get right on you tail, and at 100-200M drop a decoy. Any closer and you get hedgehogs. Any further and it doesn't work. What you want to happen is for the destroyer to magically stop on a dime and ping away at that decoy. You quickly turn and launch a torpedo at it. Careful though, as it does tend to have some drift. Aim for the middle of the boat.

2- Leave a fan behind you. Something like:

S

X Y Z

DD

Where you are S, and the destroyer is DD. You leave a screen that blocks you out even as you leave. Do it by turning tightly and dropping decoys, then turning back into the screen. Marking you map as you do this can help. It's not always effective, but it's about the best I can come up with.

Otherwise, your only hope is homing torpedos. Late war destroyers are simply nasty with their better sensors and better crews.

[meduza]

Thanks, predavolk!

Originally Posted by predavolk

Cold (i.e., not aware of you) = about 800-1000M
Hot (searching for you) = 1500M
Pinging = 2000M at best

What speed did you had in mind when you mentioned those figures? Hopefully not All stop, Rigged for silent running?

My decoy tactic differs slightly from yours. I release a decoy when DD is above me, run at flank speed while in her buffles, then slow down. The DD will detect the decoy, make a DC run, and hopefully turn in opposite direction.
Using this tactic, I eluded DD for a while, but they soon reacquired my position.

You're right about mapping the decoy positions, it is helpfull. Here's a map of that attack:

The center of the circle marks my position when the DD turned towards me, the arrow of that circle shows the position of DD at the same time.

[Hanomag]

When you are in a U-boat ALL DDs are UBER!