Escort see me without pinging
 

I'm running under water on silent but when I come close to escort like 1000m I'm not stealth anymore and soon after that start pinging.
I tryed to turn off engines but anyway can see me.
Some kind of sonar or what?

The British called it ASDIC (acronym for Anti-Submarine Detection Investigation Committee), the Americans called it sonar. During WW2 it was the main ASW detector against a submerged U-boat of Allied escorts. To evade it, there's a couple of solution:

• Firstly, since it's useless against surfaced U-boats, stay above as long as you can and preferably make attacks on the surface at night (till radar appears.)
• Secondly, if you have to be underwater, try to dive deeper.
• Manoeuvre out of the beam of the escorts, keep your distance and get inside the ASW ship‘s baffles
• Try to minimize your silhouette by keeping the aspect angle close to 0° or 180°.

yeah I was able to manage with keeping some distance and using 0 and 180 angles. this also helping when they are hunting with sonar so I managed to escape once.

Keep in mind that from '42/43 the chances were against the U-boats so historically it's completely accurate being detected and sunk by escorts no matter what you do. In the late war returning to base is considered a success and should be rewarded with the Knight Cross.

I'd go further and suggest that anyone willingly leaving port after 1942 needs to have their head examined.:huh:

I only do it because Doenitz knows where I live. The escort vessel follows us out to make sure we leave...

KH

I'm playing 42/43 because I like to use bigger u boats with some technology torpedos and equipment. Also it's bigger challenge to test your skills. Now I'm hunting one large convoy for the 3rd time.Following that covoy for about 3000 km.
At the beginning was terrible storm and 0 visibility for like 600 km + they were manevouring to make me lose them so I almost lost them 2 times. :ping: now I'm done with torpedos and fuel is also very low so I'm returning from good hunting.

:rotfl2:

Very good.:yep:

When they ping, go deep...
 

I play starting at 1939 (now on Jan 1940) and here's my bit of advise....

One. Avoid engagements in shallow water! That includes the English Channel and the North Sea. There are times you can't dive below 50 metres and you risk scraping your boat on the seabed. That way, you won't get locked on by a Destroyer, ensuing a bloody surface battle or a psychological (and deadly) game of sub vs depth charges. Do it on the Atlantic where you have 100+ metres of deep water to work with.

Two. I've learned this one when I went against a convoy at night. I fired a complete salvo of torpedoes (4 against a very large merchant and 2 stern against another boat behind me). I was in the middle of them all with destroyers actively searching. As soon as I fired all of them, I dived to 100 m at flanking speed and headed the opposite direction. As expected, the escorts followed me and they started depth charging me. I ran silent, dived deeper to 160 m, altering on flanking speed and 1 kts depending on the situation. 20 kabooms later and after going into another direction, I've successfully lost them without damage.

Moral. Depth is the key.

And oh, poke your periscope when you're not moving - it creates a wake that can be seen on clear waters. I retract it when I need to correct my positioning.

this things are very good known. but for periscope I dont use it a lot I'm basing on hydrophone so periscope for me is only to find interesting targets and after to select them when firing torpedo but also I'm using periscope at very low height that mean I dont see whole time because of waves so this helps a lot. so they ofthen never see my periscope but for engaging my targets in convoy and escape I'm using different techinq

One of the more interesting anomalies of the war is that the acronym seems to have been made up after the name was given, since there never was any such committee.
http://uboat.net/allies/technical/asdic.htm

Which stands for SOund Navigation And Ranging. :sunny:

Seems we have old captain :salute:

I think nobody answered the original question which I believe was: How does a destroyer detects u-boat which sits dead silent underwater ? so this situation is very common - if the DD is going just right above you or close enough, he will always detect you somehow and will start pinging, leaving you guesing how did he spot you in the first place ? I'm guessing this has something to do with DD sensors of SH3.

This is a very good idea. But as i know, within GWX the visible height for the peri is 0 cm. That means, that anyone can see your peri when it´s higher than 1cm above the water. LSH and CcoM changed this to 15 or 20 cm.

The other aspect is your noice. If you not running in absolute silent mode (Schleichfahrt) and with very low speed the escorts can hear you without pinging. In some mods you can see it on nav map - there is a half circle in front of some destroyers. Inside they are able to listen for your sub.

In real live it´s very difficult to find a peri if the sub below drives less than 4kn. I had often the chance to try it out, when i was in the german navy. In these cases i did know the area the sub was inside - i only found the peri in two of ten times. The commander of the sub did use his peri only fpr 20 seconds and lowers it than.

Point is to stay undetected with silent running and clever manevours. Also while engaging more then 1 target at the same time priority is to try hit both targets at the same time giving other target no chance to defensive manevour

Exactly point is to use periscope as short as possible when enemy is closer then 4-3km.
It is hard to find but you need to take that there is not only 1 person who is watching for submarines and periscope.

Look at this one sonar escape :) http://youtu.be/hytA7rcq-X0?t=58s

I had a very good navy-glass (Zeiss) when searching the peri and the sub was in a circle with maximum 2km. 20% is a very well result in this case. The periscopes in the old days were a little bit smaller then now. So in the past the peris were very hard to see if the commander used it quickly.

In the game they start to search for the sub, if they get any reason. If you don´t show your peri or conning tower they do not search you until the first torp hits a target - or someone with passive sonar is able to hear your sub. That´s it. In 9 of 10 cases i´m able to go inside a konvoy with my sub until 1942 (VII or IX). Later it´s nearly impossible. I play LSH5.1 at 82% realism.

@RussaX37: Good point mate. I should read more tutorials on hunting with the hydrophone.

@sailor_X: My educated guess is that they've heard you in the first place, maybe, while positioning yourself ahead of the convoy or when you're catching up to them. With that, the escorts will start doing a [paranoid] pattern search around the convoy. I've caught the attention of one destroyer just by approaching them (my mistake) - good thing I sank the poor warship first.

Errr.... someone correct me if I'm wrong.

Nop, there were dozens of times during my careers when my boat happens to be well submerged doing slow speed in 30 meters depth even in silent running while patrolling DD accidently takes course towards me if distance is close enough he spots me no matter what. This is somewhat annoying and is lacking a logical explanation and I usually used to blame imperfect DD sensors of SH3 though.

I`m unable to explain this. When you are deeper than peridepth and run in silent mode the escorts should not be able to find you. I believe that in the sensor-management of the escorts is a small bug. Perhaps someone could check the passiv sonar performance?

I'm not sure where this idea of complete invisibility comes from.

You can do everything right and still get detected! The closer you are, the greater your chances of being detected. The closer to being broadside to the escort, the greater your chances of being detected. If you raise your periscope, the greater your chances of being detected. The later in the war, the greater your chances of being detected. The calmer the seas, the greater your chances of being detected.

All this is true even if you are at silent running and low RPMs.

If you run across the bow of an escort, even at silent speed, odds are good you will be detected.

Just chalk it up to someone dropping a wrench or farting too loud in the head.

Steve