Escort see me without pinging

[RussaX37]

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?

[allievo]

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°.

[RussaX37]

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.

[allievo]

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.

[Kielhauler1961]

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

[RussaX37]

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'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.

[u crank]

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


:rotfl2:

Very good.:yep:

[aya]

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.

[RussaX37]

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

[Sailor Steve]

The British called it ASDIC (acronym for Anti-Submarine Detection Investigation Committee)...
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

...the Americans called it sonar.

Which stands for SOund Navigation And Ranging. :sunny:

[RussaX37]

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:

[sailor_X]

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.

[Paulebaer1979]

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

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.

[RussaX37]

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

[Paulebaer1979]

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.

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.

[aya]

@RussaX37 (http://www.subsim.com/radioroom/member.php?u=320820): Good point mate. I should read more tutorials on hunting with the hydrophone.

@sailor_X (http://www.subsim.com/radioroom/member.php?u=313052): 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.

[sailor_X]

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.

[Paulebaer1979]

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?

[RussaX37]

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?

https://www.youtube.com/watch?v=hytA7rcq-X0&feature=youtu.be&t=58s

[maillemaker]

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

[Kielhauler1961]

Periscope glass reflection from the sun? It wouldn't surprise me in this game and I take care never to leave my 'scope up for more than a few seconds at a time. Follow the link on the RN 'Perisher' course and you will see what I mean about proper periscope discipline. There was a BBC documentary about it many years ago. I remember it well and its lessons have been a great help to me in my SH3 'careers'.

In GWX there are some elite DD's with crack crews that have every sensor available running at maximum efficiency, unlike us.

They can DF radio chatter, pick you up beyond normal visual or sonar detection range and probably even 'smell' you underwater.

The No. 1 sub-killer, Johnnie Walker, had a team of ASDIC (and later Radar) specialists who had an uncanny nose for finding a contact and these guys just get better and more numerous as the war drags on.

Perisher link: http://en.wikipedia.org/wiki/Submarine_Command_Course

Walker link: http://en.wikipedia.org/wiki/Frederic_John_Walker

BBC 'Perisher' Documentary Part 1 (you won't be disappointed): http://www.youtube.com/watch?v=H1wr8J-edbo

Take care, it's dangerous out there. :o

KH

edit: If we can 'cheat' by tweaking our boats and/or crews beyond historical limits, we cannot complain if our enemies do exactly the same...:shifty:

[maillemaker]

The four-month course is run in four stages, the first and third involve learning ashore in simulators, while the second involves learning at sea. The fourth phase is the assessment, during which the candidates (of which the maximum is six) show their ability to command a submarine unaided during war-like conditions. The success rate for the SMCC is only 70% and, on failing, candidates are prevented from serving on submarines in any capacity.

:o

What the heck is the purpose of that????

Steve

[Kielhauler1961]

@ Steve,

It's the same principle why many airlines will not allow a co-pilot who has failed to make the grade for Captain to serve aboard a commercial aircraft after the event. American Airlines, I believe, brought this in and it has been adopted by other carriers, but not all.

Failure brings career ruin, an end of dreams. Some can accept that but many cannot.

There have been instances of failures being allowed to continue serving in a junior capacity in the past which have brought disaster. Some were deliberate as a way of getting 'even' with the system that rejected them, others because they were not competant anyway and should have been dismissed but slipped through the system.

It cannot be allowed for a failed professional to endanger any vehicle by design or by accident - they have been tested and found wanting and the system demands that they be rejected for the safety of others. That is the cardinal rule in safety-critical professional situations.

One strike and you're out. Where lives are at stake, there is no second chance.

KH

[maillemaker]

I just watched it, I felt very bad for the guys who did not make it.

It seems to me a terrible waste of resources. To take people with a decade's worth of naval experience, experience sufficient to even put one in the running for command, and then to throw it away because they were unable to pass the test.

I guess I can see this thought that someone rejected by "the system" might harbor resentments about that and try and sabotage the system in retribution, but I would think that someone able to make it into command school would be above that sort of thing.

I suppose they have more candidates than subs so they can afford to be choosy.

Steve

[RussaX37]

I watched too. Seems very stressfull. Yeah it really shame to be rejected after that long time and never be able to come back. :doh:

[maillemaker]

I'm also astonished by the up and down calesthenics of the periscope. I wonder today if they even use them with actual human-eye-optics.

I could see a periscope with a "head" made up of dozens of cameras that aim in a complete 360 degree circle, probably smaller in profile than an optical scope.

You pop this thing up above the water for 2 seconds, let it record hi-res images/movies, then pull it down and analyze it on a computer screen. Probably have a computer do relative motion analysis and tracking all by itself.

Steve

[Kielhauler1961]

I sympathised with the guy who had fishing boats on the brain.

I have a similar problem with motor vessels off the East coast of England but, unlike the peacetime sailors in the film, I can at least sink them.:D

KH

[Marcello]

I'm also astonished by the up and down calesthenics of the periscope. I wonder today if they even use them with actual human-eye-optics.

I could see a periscope with a "head" made up of dozens of cameras that aim in a complete 360 degree circle, probably smaller in profile than an optical scope.

You pop this thing up above the water for 2 seconds, let it record hi-res images/movies, then pull it down and analyze it on a computer screen. Probably have a computer do relative motion analysis and tracking all by itself.

Steve

As far as I have read the Virginia SSNs and some others boats of the very latest models actually do have what you describe.

[Kielhauler1961]

RN pioneered their development and they equip the Astute class subs.

http://en.wikipedia.org/wiki/Photonics_mast

KH

[RussaX37]

I'm also astonished by the up and down calesthenics of the periscope. I wonder today if they even use them with actual human-eye-optics.

I could see a periscope with a "head" made up of dozens of cameras that aim in a complete 360 degree circle, probably smaller in profile than an optical scope.

You pop this thing up above the water for 2 seconds, let it record hi-res images/movies, then pull it down and analyze it on a computer screen. Probably have a computer do relative motion analysis and tracking all by itself.

Steve

Yeah I'm wondering too what they are using on the latest models and does they even use any kind of pericope which goes on surface.

[maillemaker]

I could also see this "photonics mast" being integrated into some kind of deployable tethered buoy, so you can get a peek at what is going on topside from the deep without having to surface.

Steve

[RussaX37]

I could also see this "photonics mast" being integrated into some kind of deployable tethered buoy, so you can get a peek at what is going on topside from the deep without having to surface.

Steve

Nowdays submarines are not so much interesting as the old ones when you have to manage with everything and such a poor conditions for crew :sunny:

[Paulebaer1979]

Nowdays submarines are not so much interesting as the old ones when you have to manage with everything and such a poor conditions for crew :sunny:
Yes that´s right. Because of the realy well sonar equipment we are not interested in "looking out" because we know allready who is around us. Type 212 passive sonar is able to detect the noise of propellers from coastal container feeder at ranges up to 100sm. Below 80sm the sonar is able to detect the lofar-noise of machine, gearbox, aux-engine. So why go up to peri-depth and look out, when we already know nearly all?

[sailor_X]

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

Indeed, complete stealth of a U-boat in SH3 is somewhat impossible. Just by monitoring noise indicator could tell a lot about it. Just make a test mission and you'll notice this too. Make a lonely destroyer come right at you and while submerged-silent running-dead stop, see what happens. Noise indicator turns red and you will be pinged. What triggers it ? You can only guess or use your imagination to figure out why or what gives away your presence to a destroyer completly out of the blue.

Let's not forget we're talking here about very first detection of a u-boat and it does not matter what angle your u-boat is facing the incoming DD keeping in mind that destroyer is unaware about a u-boat nearby. In SH3 all that matters is the distance and how close DD is passing by. But the distance itself shouldn't be the key of primary detection if you're being extremly carefull about noise.

And then of course when you don't get any answers to why does it happen you're starting to make up things like somebody dropped a wrench or farted at the wrong moment, however these odds are not modded in SH3 (I wouldn't mind if it was)

This event to HOW a DD might find you without using a passive sonar first - would be a magnetic anomaly detection devic. However the usage of this kind of technology was very closely linked to aircrafts and not to warships and of course it's not covered in SH3 nor in other supermods that I know.

Conclusion: Too sensitive detection sensors ? I'm not 100% sure, but I think it might be it..

[maillemaker]

It's farts.

Steve

[Tango589]

It's farts.

Steve

Yeah, Bernards' been cooking his famous cabbage and sprout surprise again...:o

[Marcello]

I could also see this "photonics mast" being integrated into some kind of deployable tethered buoy, so you can get a peek at what is going on topside from the deep without having to surface.

Steve

It would not be stable, I suspect.

[Paulebaer1979]

Indeed, complete stealth of a U-boat in SH3 is somewhat impossible. Just by monitoring noise indicator could tell a lot about it. Just make a test mission and you'll notice this too. Make a lonely destroyer come right at you and while submerged-silent running-dead stop, see what happens. Noise indicator turns red and you will be pinged. What triggers it ? You can only guess or use your imagination to figure out why or what gives away your presence to a destroyer completly out of the blue.

That was my job yesterday afternoon. I tested it with Clemson, Hunt I-III and C-Class. First test was with destroyers at low speed (5kn). When i was in a IXD2 (and XXI) at 20m silent running all stop. Below 400m the indicator went to orange, then to red and the destroyers started to ping.
With higher speed of the destroyers they could come closer - but they found every time. The only chance to be not found is going deeper. Below 120m they didn´t recognice me - even when i was mooving with ahead slow.
So in SH3 they have a MAD-system wich isn´t known by the BDU. Damm!:/\\!!

[maillemaker]

I have always assumed that the logic was that no submarine is completely silent, and so if they get close enough a diligent passive operator will hear the sub.

While you are in the sub submerged at any depth you are always hearing creakings and groanings from the boat.

Steve

[Paulebaer1979]

While you are in the sub submerged at any depth you are always hearing creakings and groanings from the boat.

Today that´s wrong. In a well trimmed sub with "all stop" you only can hear the crew. The hull doesn´t make noise because the pressure doesn´t change - if the sub don´t change its depth.
I guess it was so in the past, too. So we have a silly bug in our nice game.

[yuanzheng]

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.
I THINK IS VERY GOOD

[Paulebaer1979]

I THINK IS VERY GOOD

The glass are nearly perfect. They are only a little bit to heavy - but sailors are strong.:D

In 2005 i used to play Stock-SH3 online - until they always kicked me from the servers a month later. They thought i was cheating - because i had the best results in the match (type VII (my sub) and XXI (other guys) against konvoy) without being killed. But it was my job being as well as i could - i wasn´t long enough in the lobby to tell that. But i´m not perfekt. My commanding officer was nearly perfekt:salute:

[Riccardo1975]

This is the one thing in SH3 that TRULY used to do my head in.

When I first started on SH3 I thought the best way to kill DD's was point blank, i.e 500-800m thanks to steam trails and bad detonators?

So i'm sat at 13m, rigged for silent running early in the pitch black morning somewhere West of Londonderry in 1000+m water, sea maybe 4m/s, waiting for a lone V&W to cross my stern, rubbing my hands in glee. Opened the tube door early, didn't raise the scope too much, not a sound.

Got within 800m and the meter starts flashing red. Great.... :shifty:

How does he spot me? He's going a good speed,(not pinging)and steering a straight course so he's not expecting anyone in the near future.

Now, luckily I use Hsie and Stieblers patches and have DD's pass directly over me all the time. If they dont think your there your safe.

Or I kill them with TIII magnetic shots. :subsim:

Riccardo

[BigWalleye]

Today that´s wrong. In a well trimmed sub with "all stop" you only can hear the crew. The hull doesn´t make noise because the pressure doesn´t change - if the sub don´t change its depth.
I guess it was so in the past, too. So we have a silly bug in our nice game.

As I have read, it was a bit different in WW2 (WW@2) They didn't have the vibration isolation and sound deadening technologies in use today. To hold depth at "all stop" you have to operate the pumps. Turn on the pumps and the escorts hear the noise. Turn off the pumps and the sub settles, as numerous small leaks let water in. And, as the sub settles, the hull compresses, increasing displacement, so you settle even more....

All this is modeled in Stiebler's "Slient Running" patch. Makes an interesting dilemma for the Kaleun!

BTW, escorts have passive hydrophones too, and they are of much longer range that active. They don't have to ping to detect you. Pinging, even today, is primarily for a targeting solution.

[Riccardo1975]

If I dive to 200m+, ahead 1/3 and set planes to surface my boat kind of skims along without sinking deeper. Above 200m DD's can hear me. Thermocline maybe?

Passive phones on ASW vessels I appreciate but they always seem to be making far too much noise for their soundman to stand a chance of hearing me creaking/RFSR at 25m? ASW trawlers I always find parked between Gib and Tangiers but the real McCoy(Tribal/BlackSwan/J&K)never seem to stop and listen.... :confused:

Rich

[BigWalleye]

If I dive to 200m+, ahead 1/3 and set planes to surface my boat kind of skims along without sinking deeper. Above 200m DD's can hear me. Thermocline maybe?

Passive phones on ASW vessels I appreciate but they always seem to be making far too much noise for their soundman to stand a chance of hearing me creaking/RFSR at 25m? ASW trawlers I always find parked between Gib and Tangiers but the real McCoy(Tribal/BlackSwan/J&K)never seem to stop and listen.... :confused:

Rich

Thermal layers are built into SH3 Commander, if you use it. If not, they are not in the stock SH3 AFAIK.

In NYGM, it seems that there is almost always one escort trolling at low speed (or even stopped, the treacherous buggers!) whenever there are 2 or more escorts.

[Riccardo1975]

So which ones right then? Should I be able to do 0 knots at 220m without my pumps running or do i have to have enough revolutions with silent running to maintain my depth and therefore make some noise either way. Ive just done my usual start of patrol depth test to 225m after leaving Thalia (24/21940)and went to All Stop. Didnt sink even on TCx8.

So will I start to sink if I rigged for silent running because of no pumps....?

What are the symbols that appear when you are rfsr? One is no reloading but the other 3?
Its all a learning curve.... :D
Cheers for helping me out chaps?

Riccardo

[Zosimus]

The reality is when you are running silent the pumps still operate. There are merely operated by hand rather than by noisy machinery. It may not be as efficient, but it's a lot quieter.

[BigWalleye]

Which is one of the things I cannot agree with.

I spoke to a former U-Boot-Kaptain about this. His words were: "That exactly is LI's job when submerged: the correct trimming. And then the boat lies stable in the water. Nothing changing. I would have shot my LI if we were to sink only because not using the pumps"

So where did this funny idea originate from?

From a number of first-person accounts, including Werner's, AFAIK. Why would he bottom the boat if it could hover? You can hold trim for a while, but the boat does continuously take on water. As long as water is coming in, water must go out or the boat will settle. How can trim be maintained without running the pumps? How can neutral buyancy be maintained without running the pumps? Technical manuals and first-person accounts all indicate that the submarine could not "hummingbird" for an indefinite period.. It could maintain trim and bouyancy for a while, but not indefinitely. Sooner or later, either pumps or motors would have to be operated to maintain depth.

[BigWalleye]

The reality is when you are running silent the pumps still operate. There are merely operated by hand rather than by noisy machinery. It may not be as efficient, but it's a lot quieter.

Yes, the pumps could be operated by hand. Everything on the boat except the propulsion could.But do you have a source that says that neutral bouyancy could be maintained indefinitely with hand-operated pumps? And that operating the pumps by hand was silent? Less noisy, sure, but a continuous noise source was all the escorts were listeing for. And sound travels a long way in water.

Does anyone have a published source that says that a WW2 submarine could mainatin constant depth indefinitely without operating electric motor-driven equipment? There are certainly first-person accounts (and technical documents) that indicate they couldn't.

[TorpX]

BigWalleye is right.

One of the tactics of hunter-killer groups was to run the U-boats ragged. That is, to stay on the surface until the boats exhausted their batteries. This would not have been an effective tactic if they could just turn off the engines and "hover".

[Riccardo1975]

Was that the "Hold down" invented by Johnny Walker?

Hopefully wont happen in GWX....

Thanks for the info. I'll have another Test Dive when I go back to Wilhelmshaven above the Shetlands. If I sink at low revolutions rigged for silent running then sh3 is accurate?

Right? :confused:

Riccardo U-111
Somewhere near Rosyth.....

[BigWalleye]

Was that the "Hold down" invented by Johnny Walker?

Hopefully wont happen in GWX....

Thanks for the info. I'll have another Test Dive when I go back to Wilhelmshaven above the Shetlands. If I sink at low revolutions rigged for silent running then sh3 is accurate?

Right? :confused:

Riccardo U-111
Somewhere near Rosyth.....

Will only happen if you have Stiebler's Silent Running Fix enabled. And for Stiebler, you must also use h.sie's patches. Get a lot of enha ncements. Worth having.

V

[Zosimus]

Yes, the pumps could be operated by hand. Everything on the boat except the propulsion could.But do you have a source that says that neutral buoyancy could be maintained indefinitely with hand-operated pumps? And that operating the pumps by hand was silent? Less noisy, sure, but a continuous noise source was all the escorts were listening for. And sound travels a long way in water.

Does anyone have a published source that says that a WW2 submarine could maintain constant depth indefinitely without operating electric motor-driven equipment? There are certainly first-person accounts (and technical documents) that indicate they couldn't.
No one is saying that the boat will hover indefinitely underwater. Yes, under normal operation the pumps are used to evacuate any accumulated water. However, under silent running, compressed air and hand pumps are used to maintain trim. Sure, one cannot vigorously operate a hand pump without making too much noise. Similarly even vigorous operation of a hand pump is not as efficient as just turning on a motor and letting it run. Compressed air will need to be used, and eventually it will run out.

However, even if the boat seems to be settling, maintaining depth is just as simple as angling the boat up slightly. Yes, this will result in a certain loss of forward motion, and yes, the boat will eventually fill up with so much water that the angle will end up being too extreme to maintain. Nevertheless the amount of water that a submarine takes on at periscope depth is negligible. The water just doesn't have that much pressure. On the other hand, at 100 meters under, the water will have 10 times the pressure and the amount of water entering will be substantially greater.

So no, I'm not saying that a boat can hover indefinitely at all stop 220 meters under the surface without running pumps. However, I don't see why someone would be all stop at that depth. If you really have run into a hunter-killer group, you need to make tracks. My boat can go 20 hours under before the CO2 hits 3. During that time I would hope to be at least 20 nautical miles away from the initial point of discovery and 30-40 would be better for my survival. So don't call all stop. Run silent, run deep, and run for your life.

[BigWalleye]

However, even if the boat seems to be settling, maintaining depth is just as simple as angling the boat up slightly. Yes, this will result in a certain loss of forward motion, and yes, the boat will eventually fill up with so much water that the angle will end up being too extreme to maintain.

Please explain how your boat maintains forward motion indefinitely with the elctric motors off. Pitching the boat while hovering - with NO forward motion - won't accomplish much.

Of course, it is perfectly possible to hold depth without running pumps, provided the boat has way on. The planes can hold it. But hovering implies no motion. No motion + no pumps = no depth control.

[Pisces]

Surely they could hand-crank the pumps, or couldn't they?

[Zosimus]

Please explain how your boat maintains forward motion indefinitely with the elctric motors off. Pitching the boat while hovering - with NO forward motion - won't accomplish much.

Of course, it is perfectly possible to hold depth without running pumps, provided the boat has way on. The planes can hold it. But hovering implies no motion. No motion + no pumps = no depth control.
Please explain how you graduated from grammar school with no reading comprehension skills.

I specifically said that the ship would be moving forward, at perhaps 1 knot. This is so slow that the ship's noise is minimal and will not be heard except at very close range.

Second, even assuming that the boat is not moving at all, the boat can be handled by adjusting its buoyancy. Compressed air can be released into the ballast tanks. If the boat seems to be pitching down, compressed air can be released into the fore ballast tank. If the boat seems to be pitching up, compressed air can be released into the aft ballast tank. Conversely air can be released and water taken in to adjust its pitch.

Will the compressed air eventually run out? Of course. However, U-boats did not sink like stones every time they stopped moving. U-boats contained sophisticated controls and had a crew of about two score to keep it working as the captain wanted.

A far more realistic adjustment to the reality of U-boat life would be to have the compressed air used up more quickly when the boat is at all stop rather than having the boat sink.

[BigWalleye]

Please explain how you graduated from grammar school with no reading comprehension skills.

I specifically said that the ship would be moving forward, at perhaps 1 knot. This is so slow that the ship's noise is minimal and will not be heard except at very close range.

Second, even assuming that the boat is not moving at all, the boat can be handled by adjusting its buoyancy. Compressed air can be released into the ballast tanks. If the boat seems to be pitching down, compressed air can be released into the fore ballast tank. If the boat seems to be pitching up, compressed air can be released into the aft ballast tank. Conversely air can be released and water taken in to adjust its pitch.

Will the compressed air eventually run out? Of course. However, U-boats did not sink like stones every time they stopped moving. U-boats contained sophisticated controls and had a crew of about two score to keep it working as the captain wanted.

A far more realistic adjustment to the reality of U-boat life would be to have the compressed air used up more quickly when the boat is at all stop rather than having the boat sink.

First, for what reason did you choose to address an insulting personal remark? I don't recall that I or anyone else on this thread directed personal insults your way.

Second, if you will review some of the previous posts, you will see that the question under discussion was whether a submarine could maintain depth control while hovering - that is, with no way on. No one was disputing the ability of a submarine to maintain a constant depth while moving. For mistakenly thinking that your comments were intended to be relevant to the question at hand, I apologize.

[Zosimus]

http://www.uboataces.com/uboat-type-work.shtml

"Thus, a U-boat [was] able to rise or sink to the depths solely by manipulating its buoyancy. Buoyancy had to be kept in check often as it varies according to the amount of fuel [on board], ammunition expended, ocean depth and salinity of water. Buoyancy can change rapidly when torpedoes are launched. A ton of positive buoyancy is created when a torpedo leaves its tube, and [it] has to be offset immediately with ballast water to prevent the U-boat from popping to the surface.

"When at rest or moving slowly underwater, a U-boat has to be handled carefully as it has a tendency to tip up or down into a vertical position. In shallow water, it can rest on the sea bed. When moving forward, a pair of hydroplanes controls the vessel’s depth. U-boat commanders prefer to keep their boat at neutral buoyancy. In this condition, the boat can dive or surface rapidly without constant dependence on the limited compressed air."

[Zosimus]

http://jtmcdaniel.com/diving.html

"Submarines are designed so that, with the main ballast tanks fulls, the weight of water displaced will be as close as possible to the weight of the boat. That is, there should be a balance between displacement and buoyancy, referred to as neutral buoyancy. If true neutral buoyancy is achieved the boat will float at whatever depth it presently is, unless something acts on it to make it rise or sink. In practice, submariners prefer to maintain a very slight positive buoyancy, so that if power if lost the boat may be expected to slowly rise to the surface.

"In addition to the main ballast tanks, which are normally kept either empty or completely filled with water, there are also several variable ballast tanks located inside and outside the pressure hull. These include bow and stern buoyancy tanks, various trim tanks, and the negative and safety tanks....

"Buoyancy and trim tanks are used to adjust the center of balance of the submerged submarine. By pumping air and water back and forth between the trim tanks the diving officer can balance the boat."

[BigWalleye]

From The Fleet Type Submarine NAVPERS 16160, June 1946, Page 177
(Available on-line at http://www.maritime.org/doc/fleetsub/)



The state of exact neutral buoyancy is probably never attained, but the approximation is near enough to allow depth control to be exercised easily by the diving officer.

In all normal submerged operations, the submarine is underway at relatively slow speeds. This horizontal motion through the water enables the surfaces of the diving planes to correct the effect of any slight positive or negative buoyancy and also to increase or decrease the submerged depth at the order from the conning officer.
From The Submarine Commander's Handbook (U.Kdt.Hdb.), OKM 1643, dated 1943:



247.) As a matter of principle, the submarine which is the object of enemy underwater pursuit should behave in such a way that it remains active, and should try to make good its escape by availing itself of every possibility, instead of simply waiting, and lying passively at the bottom. Activity on the part of the submarine always offers the best chances of shaking off the enemy.
From their training manuals, it seems that neither the USN nor the KM was aware of the possibility of a submarine remaining motionless at a constant depth. These manuals describe practical operations, not theoretical possibilities. (The theoretical possibility of establishing neutral bouyancy, and thus remaining stationary is indiputable. The question is whether this was done or could be done operationally, more especially in combat.)

[Riccardo1975]

Thankyou for all the info. Basically my boat constantly leaks so I have to run the pumps all the time to maintain a set depth. Which means I'll always make a noise when underwater. So if I sit on the bottom at say 160m, rigged for silent running will my boat slowly fill with water? :rolleyes:

[Sailor Steve]

Basically my boat constantly leaks so I have to run the pumps all the time to maintain a set depth.
No. The boat leaks enough so that you have to run the pumps sometimes when moving very slowly. When silent running you still must maintain enough forward momentum to use the dive planes to maintain your depth. It means you can't "hover" like the game allows. The boat will sooner or later begin to sink.

Which means I'll always make a noise when underwater. So if I sit on the bottom at say 160m, rigged for silent running will my boat slowly fill with water? :rolleyes:
Very, very slowly. You will run out of oxygen long before there is enough water in the boat for you to notice. It will all be below the deck in the bilges.

[Riccardo1975]

Thanks steve! Can i hell get your loading screens to work... :(

[BigWalleye]

No. The boat leaks enough so that you have to run the pumps sometimes when moving very slowly. When silent running you still must maintain enough forward momentum to use the dive planes to maintain your depth. It means you can't "hover" like the game allows. The boat will sooner or later begin to sink.


Very, very slowly. You will run out of oxygen long before there is enough water in the boat for you to notice. It will all be below the deck in the bilges.

Thank you, Steve, for explaining simply and clearly what I (and others) were struggling to communicate.:up:

[Lanzfeld]

I cant recall....

Is there a flooding level indicator in SH3 or SH4?

[CCIP]

I cant recall....

Is there a flooding level indicator in SH3 or SH4?

Yes, but it's per compartment. The compartments will show up with a "water level" on the damage control screen if they're flooding, and if you hover your mouse over that comparment, it'll tell you how long it is until the comparment reaches maximum flooding level, and how long it's going to take to pump the compartment out. If the time to pump out is longer than the time it'll take for it to flood, you're in trouble :timeout:

[Zosimus]

No. The boat leaks enough so that you have to run the pumps sometimes when moving very slowly. When silent running you still must maintain enough forward momentum to use the dive planes to maintain your depth. It means you can't "hover" like the game allows. The boat will sooner or later begin to sink.


Very, very slowly. You will run out of oxygen long before there is enough water in the boat for you to notice. It will all be below the deck in the bilges.
To the extent that your post described the NYGM mod, or H.Sie mods or whatever other mod, I would agree.

Such behavior is not modeled under the standard GWX mod.

Additionally, in real life, should a U-boat lose power or go all stop it would not sink but rather rise slowly to the surface. Forward motion is required not to keep the boat from sinking but to keep the boat from rising.

[BigWalleye]

Additionally, in real life, should a U-boat lose power or go all stop it would not sink but rather rise slowly to the surface. Forward motion is required not to keep the boat from sinking but to keep the boat from rising.

RL, whether the boat rises or settles depends on whether it is trimmed heavy or light. If it is trimmed to have some positive bouyancy, then it will rise. If trimmed to have negative bouyancy, it will settle.

Whether the boat is trimmed positive or negative depends on the situation. Generally, a slight positive bouyancy is preferred as a safety measure. In the event the boat loses all power, it will slowly rise to the surface.

In combat, when periscope observations were planned, it was safer to carry some negative bouyancy. The boat would have less chance of broaching, breaking the surface and exposing the periscope shears and the sail.

This topic is treated in NAVPERS 16160., and discussed in many of the first-person accounts, including Werner.

In-game, NYGM builds in negative bouyancy, GWX positive bouyancy, and stock SH3 lets you hover like a hummingbird. There is a parameter in a text file that you can change to adjust both amount and direction. I don't recall which file, but it has been discussed on this forum.

[Sailor Steve]

To the extent that your post described the NYGM mod, or H.Sie mods or whatever other mod, I would agree.

Such behavior is not modeled under the standard GWX mod.
This is true. I wasn't thinking of the game at all, but of real life. My apologies for any confusion.

In-game, NYGM builds in negative bouyancy, GWX positive bouyancy, and stock SH3 lets you hover like a hummingbird.
I can't recall the exact change, but it's my understanding that the positive bouyancy in GWX was removed after some complaints, and is not there in GWX3.

There is a parameter in a text file that you can change to adjust both amount and direction. I don't recall which file, but it has been discussed on this forum.
I don't know either, and I wish I did because while GWX is my mod of choice I like the 'sinking' function. It keeps me honest.

[Zosimus]

My personal experience, with GWX, is that when I set the depth for 25 meters and run silent I typically hover around 24 meters and never reach the 25 meter depth.

[BigWalleye]

I don't know either, and I wish I did because while GWX is my mod of choice I like the 'sinking' function. It keeps me honest.

Steve, I found the thread:

http://www.subsim.com/radioroom//archive/index.php/t-201357.html

The relevant post is one up from the end, by VanJast.

The file is Data/Zones.cfg, section PumpsXXI, parameter Flotability. VanJast says that he reduced the value from .15 to .005 and got a very slow settling. (50 m in 12 hours).

Although VanJast is a very reliable source, I was a little concerned because, when I checked the relevant file in GWX3 expecting to see positive bouyancy, the Flotability value was zero. If the positive bouyancy has been removed from GWX3, a zero value would be expected. I haven't tried tweaking the Flotability (and don't plan to), but for those who want to, Van certainly has shown us how.

[U-15]

My personal experience, with GWX, is that when I set the depth for 25 meters and run silent I typically hover around 24 meters and never reach the 25 meter depth.

Same here. I use GWX3 and when crawling along (submerged) at 1 knot, my depth is always a couple of metres less than ordered.
I always assumed, (probably wrongly), that it was due to sea density.

The differing viewpoints in this thread, have obviously sunk that assumption. :hmmm:

I can't remember what it was like in the stock version, as I have only used GWX for the past 5 years or so.

[Aras]

Same here. I use GWX3 and when crawling along (submerged) at 1 knot, my depth is always a couple of metres less than ordered.
I always assumed, (probably wrongly), that it was due to sea density.

The differing viewpoints in this thread, have obviously sunk that assumption. :hmmm:

I can't remember what it was like in the stock version, as I have only used GWX for the past 5 years or so.

I don't know if this is related to it but i discovered that you need to click past the number if you want the number take place. Let me explain, if you want 5 knots speed, then you should click somewhere between 5 and 6 on the gauge. If you click on 5, then you will probably get 4 knots. Same for depth etc...

As you do, I run GWX and I run it from the day one. I don't know how the stock game is except for the one time I opened it and immediately closed it. I knew GWX by then and even the ships seemed ugly in the stock game after knowing how they looked in GWX.

[U-15]

Thanks Aras, that's the way I have been doing it.:up:

[Sailor Steve]

Steve, I found the thread:
Cool! Thanks!

[Zosimus]

If the problem is simply that you didn't tick past the required number, then the depth should show 24 meters regardless your underwater speed.

[BigWalleye]

Cool! Thanks!

The ability to easily set the trim got me thinking: RL, the boat's trim was not constant, and varied with every dive. The accuracy and reproducibility of the trim depended on the skill of the diving officer. So I decided to use SH3 Commander to inject at least a little unpredictability into the trim value.

The following section can be copied and added at the end of the file Randomized events.cfg in SH3C.



;-----------------------BOAT VARIABLE TRIM
[0:data\Zones.cfg]
ChooseFrom=16
RndMidPat=1

0_PumpsXXI|Flotability=-0.05
1_PumpsXXI|Flotability=-0.03
2_PumpsXXI|Flotability=-0.01
3_PumpsXXI|Flotability=0.01
4_PumpsXXI|Flotability=0.03
5_PumpsXXI|Flotability=0.05
6_PumpsXXI|Flotability=0.07
7_PumpsXXI|Flotability=0.07
8_PumpsXXI|Flotability=0.09
9_PumpsXXI|Flotability=0.09
10_PumpsXXI|Flotability=0.11
11_PumpsXXI|Flotability=0.11
12_PumpsXXI|Flotability=0.13
13_PumpsXXI|Flotability=0.13
14_PumpsXXI|Flotability=0.15
15_PumpsXXI|Flotability=0.15

;-----------------------end BOAT VARIABLE TRIM

The values are intended to represent an LI of average competence at an early stage of the war, and are biased to include the NYGM negative bouyancy. The trim value will change at the start of each game session.

If anyone tries this, please let me know what you think of it.

[Sailor Steve]

I think the idea is awesome! :rock:

The bad news is I haven't played for a long while because of my ancient computer. On the other hand I'm tempted to set everything up again just to give it a test. I'm always amazed at what Commander can do. :sunny:

[BigWalleye]

I think the idea is awesome! :rock:

The bad news is I haven't played for a long while because of my ancient computer. On the other hand I'm tempted to set everything up again just to give it a test. I'm always amazed at what Commander can do. :sunny:

OT, but yeah, Commander is really powerful. There are so many things it is capable of. My minefield map updates when I return to port. Torpedoes often have a depth problem, but not all the time (and sooner or later OKM is going to fix it.). Inexperienced LI can't always hold the boat steady (as Werner described). Merchant ships change their look as the war goes on. The ambient noise in the boat, and even the band music is always changing. (Thanks, Steve!) And I don't know where Fühler gets all the girlie pictures!

And those are just easy knockoffs. Somebody energetic could make landscapes that change with the seasons, or government issue equipment upgrades. SH3C is a gift that keeps on giving. Kudos to Jscones!

[LGN1]

Hi BigWalleye,

just to be clear, your SHC mod will not work in GWX because the *.zon files of the submarines do not contain the pump. The NYGM slow-sinking mod requires changes to the *.zon files.

Have you tested negative Flotability values in NYGM? I wonder whether this has any impact because an 'empty' should not get 'more empty'.

Regards, LGN1

[BigWalleye]

Hi BigWalleye,

just to be clear, your SHC mod will not work in GWX because the *.zon files of the submarines do not contain the pump. The NYGM slow-sinking mod requires changes to the *.zon files.

Have you tested negative Flotability values in NYGM? I wonder whether this has any impact because an 'empty' should not get 'more empty'.

Regards, LGN1

Negative Flotability values work in NYGM. The equivalent buoyancy is not symmetrical though. A Flotability of -0.15 (positive buoyancy) causes an initial loss of depth of about 2 m per hour from PD. A Flotability of +0.15 (negative buoyancy) causes an initial gain of 10 m per hour, again from PD. Of course, it the modeling is correct, movement in either direction will accelerate over time. Buoyancy is a force acting on the boat. Force equals mass times acceleration. So, for a constant force, the movement will accelerate, changing depth faster and faster until the unbalanced force is resolved.

I don't understand what you mean by

...an 'empty' should not get 'more empty'. Zero buoyancy does not represent anything being empty. It means that the weight of the boat (including all ballast water it contains) is equal to the weight of the volume of water the boat displaces. When surfaced, the boat will displace a volume of water which weighs more than the boat weighs (again including all ballast water it now contains). But that does not mean that the boat has been emptied of all ballast. Generally, some ballast water is retained in the tanks to keep the boat from bobbing like a cork (unpleasant for those inside). The difference between emptying the negative ballast tank ("Blow negative.") and emptying the safety ballast tank ("Blow safety.") is the difference between a controlled surfacing and an emergency surfacing. Both create positive buoyancy, but blowing safety creates (hopefully!) a lot more. And trimming the boat for positive buoyancy while submerged involves moving some water out of the trim tanks, not out of the main negative buoyancy tank. So there is still plenty to empty when cruising at depth with slight positive buoyancy. All of this is explained well in NAVPERS 16160.

I apologise if this does not answer your question. I am trying to undertand what you meant.

And sadly, Steve, LGN1 is correct. In GWX3, the Flotability parameter has no effect on the boat's ability to hover like a Huey. Took it to 80 m, stopped, and it stayed right there for hours.

[Sailor Steve]

Interesting. It doesn't bother me too much, though, as I never stop underwater and use that anyway. It is, however, something that was built into Aces Of The Deep twenty years ago. "Captain, we can't maintain depth without running the pumps!"

[LGN1]

Hi BigWalleye,

sorry for the late reply. I was confused by the word 'flotability'. I thought it was connected to 'floodable' and thus, meant that the compartment could be flooded by a certain amount. In this case a negative value was a mystery for me.

Regards, LGN1

[BigWalleye]

Hi BigWalleye,

sorry for the late reply. I was confused by the word 'flotability'. I thought it was connected to 'floodable' and thus, meant that the compartment could be flooded by a certain amount. In this case a negative value was a mystery for me.

Regards, LGN1

Yeah, "flotability" is not in my dictionary, either. And, since it operates in the reverse sense to buoyancy (positive "flotability" makes the boat heavier), it maybe should be called "sinkability.":) Anyway, I hope you didn't feel dissed by my Physics 1 explanation.

Merry Christmas!