DD's can't use their hydrophones to hear you on the surface. They rely on visual or radar contacts. When you submerge, they use the hydrophones.

If you're closing on a convoy on the surface at ahead full, you won't be heard, so you won't be attacked until you're spotted. If you dive to periscope depth, but don't adjust your speed, you'll be advertising your position on the hydrophones, and you'll attract the escorts like fleas to a dog.

Decks awash is technically surfaced. They won't pick you up on the hydrophones until you're fully submerged.

Until then, I guess your noise tends to blend in with the surface turbulation, or the sounds of the other vessels in the convoy.

Dealing with DD's in harbors is more like a chess match than an evasion. There are a lot of potential obsticals that you can use to cloak yourself or use to trap the ships above. Be sure though that you've got plenty of air as you could be submerged for a very long time.

You can hide inside the individual ship docks, will make it hard to find you and hard to hit if they do manage. Hide next to a ship or better, a sinking ship (just be careful as they still move once sunk so if you tc you might end up drifting into it) to protect yourself. Escorts don't seem to carpetbomb dc's next to a tanker. Eventually it may give up and go back to it normal patrol and you can move around again. If not, best option in my experience is to sink the thing. Lure him into a position such that he has to come at you directly astern or from the bow (just as long as he can't flank you) and have your weps plot a solution when he's 400m away and fire once its ready (an electric set at 45m) or if using manual be sure to release the eel when he hits 350m to be sure the torpedo has enough time to arm itself.

P.S. Silent speed when your in trouble with little room is always 1 knot and always try to set your rudders to 2-4 degrees in either direction. Constantly turning helps to make you a bit harder to find.

Hello,
only to put some more oil into the fire :lol:
I do not know how SH3 handles this, but a submarine which is at periscope depth can usually not be detected in reality, for the following reasons:

Hydrophones: the surface noise of waves, even when it is almost calm, prevents a detection, if you do not crash a hammer against the hull. Running silent with up to 150 propshaft rpm will not give away your position. Just do not stick the periscope out too long ...

Early sonar/Asdic: the detection cone in front of a destroyer will not find a sub at periscope depth, because even its upper face has a downward angle which will pass below the boat. A boat that is so near as to be hit by the impulses, will 1st most probably be rammed in the next second with or without detection, and 2nd a hitting impuls would not be directly reflected to its source as long as the destroyer moves.

Only possibility is a thermal or density layer below the sub that would reflect the sonar impulse upward again, and then "touch" the boat. Even then the physical situation has to be in a way that those impulses are directly reflected.

Both statements are from a book "Submarine hunt and detection" from the 1960 ies, and even in that time with developped hydrophones and sonar etc. it was virtually impossible to find a sub at PD.

The only "classic" sub game with Diesel/electric boats i know of, that represented that behaviour, was "Wolfpack". If SH3 can be tweaked to represent this i would like to see it. Speaking of oil again lol ...

Greetings,
Catfish

Hehe, well, from the sounds of it there are 3 components to staying alive in shallow waters:

1: Luck

2: Finding a good hiding spot

3: Not being stupid enough to go in there in the first place

Sound about right? :p
That being said of course, a lot of good targets sit in harbors and convoys are often easy to work with in the limited inter-island waterways. Oh well, I've been wanting to try looking for some of the bigger seagoing targets since those seem to pose a different kind of challenge altogether in that first you have to find them, then get into position with some good thought, and then manage to get away with nothing but depth to hide in.

I did manage to bag an illustrious carrier last night, it was quite a catch, but then I had to spend the next few hours at 150m trying to evade all 6 of the carrier escorts hunting me down...

Out of curiosity, I know that op depth on a VIIB is stated at 150m and max at 220m but I've seen posts here talking regularly about operating at max depth and some that go much further than that... What is the real crush depth on these, and how bad of an idea is it to get right down on it?

@Catfish
Those are interesting points... though I'm not sure how accurate they are, only because if they were really the case, U-boats would have simply just stayed at PD when trying to evade and never gotten sunk because they could sneak away easily. That being said, there are also a lot of other factors there that might be in play and I think it would be worthwhile to include those modellings if they are accurate... GWX et al have made the game so much more interesting and realistic with their addons, but they've essentially made it a lot harder too. Wouldn't it be nice if adding realism could help out in some little way to counteract that. :)

Greg

Hello treblesum81,
the numbers and situations are from the book i mentioned, and i believe them to be exact. Mr. Topp, who had sunk quite some tonnage, and survived the war, also mentioned that strategy. In fact he said he usually never dived to more than 30 meters for exactly that reason.

A boat hearing a destroyer start its attack run could go to full speed undetected, the destroyer is virtually blind during the attack run. If you are at PD the destroyer has to be REAL fast not to be sunk by its own depth charges, being adjusted for exploding at 15 meters.

Bystanding destroyers would as well not hear you because of the attacking destroyers cavitation noises, and no one wanted to ruin his ears hearing exploding charges at the hydrophone. As well in the first years of the war depth charges often exploded at the wrong depth, having similar problems with depth settings as the torpedoes of all nations.

If the enemy exactly knew where you were (spotted your periscope) you would probaly dive deeper to evade the depth charges: One reason is the deeper you are the more the enemy has to calculate sinking speed of the charges against the movements of the sub. And as well a depth charge in say 200 meters does not have the kill radius it would have in shallow waters - water pressure is your friend here.

Even today e.g. a diesel-electric russian "Kilo" sub can only be found by means of exhaust Diesel detection when running at PD charging the batteries, and the Diesel-generated noise.
As soon as it switches to electric propulsion the only possibility for detection is to use submerged sonar buoys, that direct the impulses upward, and are in that case able to detect the sub. Certainly there are other detection strategies today, but not in WW2 anyway.
One of the advisors for SH3, also a real ex-U-boat commander from WW2, said the SH3 vanilla game was already much too hard compared to reality.

Greetings,
Catfish

Good post http://www.psionguild.org/forums/ima...ies/pirate.gif

Agreed, very good post..

I'm interested to know more of the reasoning behind how the game is harder than it was in real life... did he elaborate any on the reasoning behind the statement at all? I know that it couldn't possibly have been as hard as its is in GWX, but the stock game was pretty easy to start with, meaning that he was basically saying that real life U-boating was like Sunday cruising with the chance of losing your life...

Speaking to the GWX team here, I think it would be fair if you all had a look into this data, as it may help to further improve balance and realism within your mod, and in addition, I imagine it would help a lot of people enjoy your addon further. I'll say though that I'm not thinking this would become an easy way to lose DD's as I'm sure there are plenty of other detection strategies that one might fall prey too, but I think that in many cases, GWX seems to model almost exclusively the aspects of U-Boat operations that serve to make life more difficult and not all that many that make it easier. Just a thought.

Greg

Good post, and it mirrors my thoughts and experiences. First, pray for a heavy sea state. That makes all the difference. Second, generally try to head towards deeper water. Keep a constant direction. Remember that the AI works from a point of contact. Get away from it! Third, use your periscope (if detected) to fight back or to run. In clearer water, the observation scope can be used to see the destroyer on its attack run (doesn't so well work in cloudier or deeper water with mods). Otherwise, keep patient, keep cool, and keep dodging their attacks. With luck, you'll evade them, find deeper water, wear them out, or run into heavier seas. Without luck they'll hit you, you'll run out of batteries, or they'll call in reinforcements.

:yep:

Well put, make course for some deep sea and hope the batteries don't run dry on you... Shalow water will end careers faster than playing for the Leafs....

But I seamed to have the best luck going as deep as I can in shallows (anywhere from 20 to 30 meters) and zig zaging. Pray for a storm, deeper waters, Hermann Goering's boys, or the water is shalow enough for the escorts to blow off their depth charge racks (seen that happen on occasion)....

Hello Greg,

I don't place a lot of faith in stock SH3 in terms of challenge to the player In all my time playing stock SH3 I never got sunk. Sadly as the other senior team members would gladly tell you, if you do action A in SH3, you will have repurcussion in Action B. Its difficult to do X without affecting Y so you have to strike compromises somewhere.

Modifying the sensors was done like it was so that the player faces real threat, because that was the reality of it, the U-Boat force was the second most dangerous force to be in, second only to the kamikaze's of the Japanese. With a 75% death rate there really is no two ways about it, to be historically true, you have to model the aspects that made U-boat operations hard.

However I disagree about nothing being there in GWX to make life easier, you have several things to assist you, such as sonar decoys, anti-sonar and radar coatings, radar warning sets. Not only that, the campaign in 1939/1940 even as far as 1941, is not exactly difficult... I can quite faithfully say that GWX models the "happy times" quite well.

Another little tip to hide your presence even more;

Lower your speed to 1kts when submerged, on silent mode it will go from 100rpm to about 50rpm. (at least on the type VIIb)
I know it's not much, but it saves the half in rpm, surely that would save some noice as well!

In terms of fatality rates there's no arguing about the numbers, though I think objectively I'd put the U-Boats as #1 as the kamakaze's had problems. Though they're missions were to be human guided bombs ensuing a near 100% fatality rate some would miss their targets or be shot down. Though there were hundreds of ships hit by these attacks, a lot of the planes were also shot down. Would be interesting to see the % of kamakaze attacks that were "successfull" in hitting their targets, doubt that it's above 75%.

There's a number of aspects of GWX that are harder than the stock, though there are some major changes that go towards the more realistic side which make the game much easier than the stock version. Trying to evade more than 4 DD's in stock is very tough (once their sonar skills get decent) and they rarely give up. GWX does a good job of simulating a real DC attack where ships would leave after a few hours rather than stick around endlessly dropping DC's till you either die or surface for lack of air. The thermal layers also really help throw off the sonar just enough that dc's will reliably keep exploding 20 or 30 m above you if you're under a layer. You can also bottom your boat (intentionally) as a tactic and the DD won't start using DC's like smart bombs on hit you with 100% accuracy (unless they've already found you).

What is working for this noob is to think about the combination of sea turbulance and thermal layer. I have read there are generally 2 thermal lines. One is just below persicope depth and one seems to be around 160 meters.

If the seas are rough it seems I can move at 2 knots at persicope depth and be pretty much invisible. Just today (Oct. 1941) I had a destroyer pass within 300 meters of my periscope-depth sub and because the seas were rough she did not detect me even though I was moving at 2 knots.

I know I would have been detected in calm seas at all stop, and when this happens I flank speed/manuever until I am below 160 meters and at that point they don't seem to be able to find me. My IXC can always stand the pressure down to 210m (haven't risked it below that, though I read it is possible) and once I am down there I'm never detected.

Moral of the story seems to be get down and deep after an attack if the seas are calm.

I have some questions regarding this:

1) do the Germans ever get a detection device (bathyspehere ?) that lets them know where the thermal layers actually are? If not, is there a mod that gives your U-Boat this ahistorical edge?

2) I read the U.S. boats had such a device and it is recreated for SHIV. Was it true the U.S. boats did, and the U-Boats did not, have this device in WWII?

3) Is this thermal layer effect recreated in SHIII GWX 2.0/2.1? My guess is yes since it works.

4) What weather conditions change the lower (160?) meter depth of the lower thermal layer?

Thanks for any input you have.









2)

@Catfish

As it turns out, I think that the shallow water detection we were talking about previously seems to have been modelled, either by GWX 2.1 or by SH3 stock (don't really know how much more of that is left after GWX 2.1 and Ubermod). Last night I attacked a convoy in rough seas, but good visibility. On a hunch I chose not to dive right away after the attack and, lo and behold, 3 DD's started searching a good distance out along the probable path of the torp, but never got close to me and my detection meter never went red. I was able to keep the attack going for a full hour at PD without ever getting within 1km of a DD.

In addition, I was able to conduct operations at 1/3 speed and off of silent running in a VIIB in 1940.

Greg

Attacking a destroyer in shallow water = FAIL