Escaping from sonar

[ralphnader23]

I was playing last night, approaching a convoy that had changed directions about 10km before my intercept point. I was about 4km off, running at 2 knots, when a Frigate starts pinging me. I've been spotted.

I crash dive, and then head down to 150m and start taking evasive action. In just a couple minutes all three escorts are on top of me. I take some damage and end up at about 230m, before I can get the sub repaired and headed up again.

I continue taking evasive action for 7 hours, making turns, starting and stopping, always moving slow and getting constantly depth charged, but I cannot shake them off my tail. All three escort ships seem to have decided that they want me very dead. Every 5-10 minutes I'm getting pinged, which seems to make it impossible to shake them.

Shortly after the 7 hour mark point they stop depth charging me, and I don't get another depth charge for over an hour, even though I can still hear them circling on the surface. I decide it's time to be more aggressive and I head to periscope depth. I still have most of my torps, maybe I can kill all three.

It's very difficult to hit warships who already know your location, who are making constant course changes, and whose speed you can only really estimate. Plus every time I come to the surface they try to ram my periscope. However I manage to hit and sink one of the three, before I run out of torpedoes.

Now I have two escorts over me, still constantly pinging me. I head back down to 40m, and cruise along at 2 knots, waiting for night. Sooner or later I will run out of air or battery and there is no way to change the status quo.

They continue circling and pinging for another 10 hours, until it's late at night. I'm past the 50% mark on air, and impatient at having been on only 8x tc for 20 hours, so I give the command to surface the boat. I end up surfacing 10m from one of the escorts and we begin to trade shots. I'm taking heavy damage and losing the gun crews fast. I manage to set off a few explosions on the escort, before I'm finally sunk. End of career.

Obviously the real trick is not to get in a situation where you have multiple boats circling and pinging out. But once in that situation is there anything I could have done differently? Is there any way to hide from the pinging at all? What kind of range does the active sonar have?

[Gerald]

Originally Posted by ralphnader23

I was playing last night, approaching a convoy that had changed directions about 10km before my intercept point. I was about 4km off, running at 2 knots, when a Frigate starts pinging me. I've been spotted.

I crash dive, and then head down to 150m and start taking evasive action. In just a couple minutes all three escorts are on top of me. I take some damage and end up at about 230m, before I can get the sub repaired and headed up again.

I continue taking evasive action for 7 hours, making turns, starting and stopping, always moving slow and getting constantly depth charged, but I cannot shake them off my tail. All three escort ships seem to have decided that they want me very dead. Every 5-10 minutes I'm getting pinged, which seems to make it impossible to shake them.

Shortly after the 7 hour mark point they stop depth charging me, and I don't get another depth charge for over an hour, even though I can still hear them circling on the surface. I decide it's time to be more aggressive and I head to periscope depth. I still have most of my torps, maybe I can kill all three.

It's very difficult to hit warships who already know your location, who are making constant course changes, and whose speed you can only really estimate. Plus every time I come to the surface they try to ram my periscope. However I manage to hit and sink one of the three, before I run out of torpedoes.

Now I have two escorts over me, still constantly pinging me. I head back down to 40m, and cruise along at 2 knots, waiting for night. Sooner or later I will run out of air or battery and there is no way to change the status quo.

They continue circling and pinging for another 10 hours, until it's late at night. I'm past the 50% mark on air, and impatient at having been on only 8x tc for 20 hours, so I give the command to surface the boat. I end up surfacing 10m from one of the escorts and we begin to trade shots. I'm taking heavy damage and losing the gun crews fast. I manage to set off a few explosions on the escort, before I'm finally sunk. End of career.

Obviously the real trick is not to get in a situation where you have multiple boats circling and pinging out. But once in that situation is there anything I could have done differently? Is there any way to hide from the pinging at all? What kind of range does the active sonar have?

you said you did a deep dive, and how much do you think that the convoy was, and how many were DD? many questions ....

[K-61]

I noted you said you were running at 2 knots. That's fast enough for them to track you. I find ordering silent running and then manually dragging the needle on the telegraph and watching until you get to 50 RPM's to be effective when combined with depth. At some point you will slip under the thermal layer [modelled in SH3 Commander although you will not know it for certain, read the notes] and be harder to track. In order to set your E-motors to 50 RPM's you either have to use the mod that allows you to do so from the speed buttons [~] key or use Shift+F2 to free roam through the boat to the chief engineer's gauges and observe the changes made to RPM from dragging the indicator pointer.

50% air left is not the time to panic. If necessary, you can drag it out until you get the "We must surface!" message. I've never been kept under long enough to get to that point, but if I did, I would surface the boat [and die] but then go into SH3 Commander and change my career status to surrendered at sea. It doesn't get you out of your predicament, but it does lend a happier ending to the lives of your Kaleun and crew. There's no way a U-boat crew would try to duke it out with three escorts; they'd be jumping overboard as fast as they could get out.

Also, the fact that they were making "dry" runs on your position tells me they were out of depth charges. From that point on they can't hurt you while you are submerged. Do not give up on evasive action, stay patient, quiet and deep and hope you eventually get away. If you do run out of air, then you must surface and "surrender" your career, perhaps after having made one last desperate attack with your remaining torpedoes. I've found that by running slow, it is always the air that gives out before the batteries, even if I have had to make some fast dashes to escape falling DC's.

[CherryHarbey]

Originally Posted by ralphnader23

Now I have two escorts over me, still constantly pinging me. I head back down to 40m, and cruise along at 2 knots, waiting for night. Sooner or later I will run out of air or battery and there is no way to change the status quo.

They continue circling and pinging for another 10 hours, until it's late at night. I'm past the 50% mark on air, and impatient at having been on only 8x tc for 20 hours, so I give the command to surface the boat. I end up surfacing 10m from one of the escorts and we begin to trade shots. I'm taking heavy damage and losing the gun crews fast. I manage to set off a few explosions on the escort, before I'm finally sunk. End of career.

You don't say whether, you went any deeper during the last 10 hours but if you stayed at 40m it was not deep enough.

As deep as you dare, you say you were down to 230m when damaged, if you were able to get back below 200m that may have been enough.
then as slow as you can maintain depth and try to keep in your enemies blind spot (their stern) until you see an opportunity to breakout of the circling destroyers.
This can take awhile (I've have 11hrs of being pinged before escaping and I'm sure others will have gone longer) but while you still have air its your best chance of survival.
Not sure what warnings, if any, you get of running out of air ,whether you start getting wounded or some dying crew, but if it was me I'd would be waiting the last possible moment before trying to surface and go toe to toe with destroyers.

[ralphnader23]

So basically the plan would be to go as deep as I can (240m?) and keep my engines going real slow (50 rpm), and then once I hear the ships pass overhead to go to flank for maybe 30 seconds, then back to slow?

I didn't surface b/c I was out of air...I surfaced b/c I got impatient at the amount of real time it was taking...plus this was only my second patrol of the career, and my first patrol wasn't terribly successful. I just don't have time to spend 2-3 hours sitting at 8x time compression trying to dodge destroyers

The convoy was a big one, I would guess over 50 ships. I don't know if those 3 ships were the whole escort or not.

How much range does a sonar ping have? 1000m?

[K-61]

With low speed it is difficult to maintain depth the deeper you go. Your boat gets compressed by the pressure, reducing its cubic volume. This makes you sink further so the only way to maintain depth is to have water flowing over your control surfaces. It is a delicate balancing act. I was once so deep that I could not maintain depth and she kept dropping lower. I was scared I would get crushed so blew some ballast to come up another 50 metres.

[U777]

If decoys exist at your current year install them on your boat and use them. They saved my skin a few times.

Also, the fact that they were making "dry" runs on your position tells me they were out of depth charges.

Good to know that they have a limited amount.

Once they get in a situation where multiple ASW ships are not having a problem with holding contact over long periods of time, it's usualy over.

Some have survived the ordeal, but most do not.
I lost a IXB in december 1944 that way.
Hunter Killer Group. No matter what I did, they wouldn't let go.
When I tryed to go deeper to escape the constant pinging, the pressure hull collapsed.

[HW3]

I routinely take a undamaged boat down to 240M and hope I am below the thermal layer. If I am, the pings change or disappear and I know they will lose me so I change course and move away slowly till they give up and leave. If the ping has not changed tone, I creep deeper to about 265M. If the ping is the same, and there are 3 or more escorts up there, I'm in deep do-do. It is going to take alot of luck to get out alive and in one piece.

[Tessa]

Depending on where you are, there's a couple of ways to deal with multiple escorts. If you're attacking a convoy in the middle of the Atlantic and can get below 200m where the depth charges can't hurt you anymore, and wait. Typically in about a hour they'll leave to rejoin the convoy.

If you get stuck with a convoy that has massive numbers of escorts where if 3 detach for 10 hours the convoy would still be safe is a major challenge. As mentioned previously, you must be at 1 knot for you to be truly running silent. Two ways I've gotten out of this, one you figure out what pattern they're running for circling, you'll need to figure out how the circles overlap so you can find the edge of their hunting zone. Get perpendicular to one of those circles and when the chance to use a flank burst or sonar decoys (or both) get out that circle and keep running. Once you're outside the area they are circling you have a potential chance to get away. If you're unlucky and they find you and move above you again its rinse and repeat.

Other way is to take out the escorts. Get into position at ~ 13-14 meters in such a way that when they drop their charges they won't ram you. Have both tubes 1 and 5 loaded with a steam torpedo set at max speed and wait till they reach 300 meters away. After the drop charges they'll typically slow down or possible stop for a moment. Even if you're aob is 180/0 if they're at 300 meters 9 times out of 10 you'll nail em somewhere and sink em. For all intent and purpose at 300m they're point blank range like having a gun point at you head a few inches away. No matter how fast they try to go or turn they can't outrun/turn you torpedo since it's speed is faster than they can react while being at point blank range. Once accoustical torpedos become available that trick can pretty much assure you that you're gonna hit them.

Finally the one sure way to escape you can do if you're down deep enough and you'll need to be farther east in the ocean. Wait for the convoy to reach it's destination (which will be several hours at least), once they arrive the escort will literally disapear.

[evan82]

Originally Posted by ralphnader23

I was playing last night, approaching a convoy that had changed directions about 10km before my intercept point. I was about 4km off, running at 2 knots, when a Frigate starts pinging me. I've been spotted.

What sort of toys they had?

[HW3]

I was playing last night, approaching a convoy that had changed directions about 10km before my intercept point. I was about 4km off, running at 2 knots, when a Frigate starts pinging me. I've been spotted.

Not necessarily. I have discovered that occasionally the escorts randomly ping just to check if anything is around, and even though your hydraphone man starts saying we've been detected, it is not necessarily so. Unless the escort starts making a run on you, you may still be undetected and safe.

[K-61]

If an escort is closing on you, you must fire from further than 300 metres away. The torpedo must run 300 metres in order to arm; if you fire at 300 metres on a destroyer that is closing on you, the torpedo will arrive at the destroyer before it has run 300 metres, due to the closure rate.

[vanjast]

You've probably come across the 'Creeping attack' tactic..

3 or more scorts attack you in sequence.

a) One ship sits a distance from you, locking you in it's ping bracket.
b) One other ship has passed and slowing down to take up a)'s position.
c) The third ship is coming in for the attack, by getting location information from a)

To counter this 'mass' attack I used to...
Sit at the hydrophone the whole time.
You just avoided b) so you have him 'on view'
a) is moving slow enough to be heard on hydrophone. Keep his bearing - you need this.
c) you can also hear, and as he starts to speed up, you flank speed towards a).. YES - flank speed towards a)

What this does.. if you time it right, you'll pass under a) just before c) gets on top of you. This creates a bit of an AI dilema for a) and c).
a) cannot drop DCs as it's moving to slowly and will blow itself up
c) cannot continue the chase or drop DC's as it will ram a) and also blow both of themselves up.

This leaves a) and c) literally stationary and out of position for valuable minutes. Now you head directly away from b)'s projected position in silent mode/speed once again.

This can go on for hours, but I eventually had the two ships ram each other. and the 3rd gave up the chase. Depth used was maximum and no less.

[K-61]

How do you guys cope with the sinking boat problem at depth? My boat can take the depth, but cannot maintain depth at 50 RPM's. For example, at, say, 210 M at 50 RPM's my boat slowly sinks, even if I order it to ascend. The only way I can get it to ascend is to increase speed, which reduces my stealthiness, or blow ballast, which you can only do so many times before you run out of air.