Seafloor's ASDIC protection

[Matyas]

I'm currently in a dilemma. I have received a radio report about a convoy travelling along the eastern shores of Britain where the sea is quite shallow (30 meters at most) and I don't know whether it is worth the risk of engagment: if an escort picks me in such shallow water I'm dead meat as I can't escape their ASDIC by diving deep. (Also the low water pressure expands the lethal radius of DCs in theory, so they don't even have to be too precise to kill me.)

I faintly remember a story told by a German U-boat commander (maybe in Discovery channel): he said that their tactics in shallow water was coming to a full stop and lying down onto the seabed. That way they were undetectable to both hydrophones and ASDIC as they didn't make any noise and the sonic (echo) waves bouncing off the seabed created a lot of "noise" that hid them.

Does anyone have any idea about whether this phenomenon (i.e. the seafloor hides U-boat from ASDIC) is modeled in SH3? Knowing this would greatly help me doing my "risk analysis" before the attack. :yep:

BTW a second question: is the lethal (or effective) radius of DCs affected by depth (water pressure) in SH3? :hmm:

[Sailor Steve]

Yes, the Germans used it, and to good effect. The Americans did it also, most notably S-36 at Lingayen Gulf. The added advantage is that the sand absorbs the blast of the depth charges, so they're not only dropping blind, but they have to get very lucky to hurt you.

The bad news is that no, none of this is reflected in the game, and it's part of the main code, so no one can change it.

[Boris]

Yeah, I've been bombed out of existence lying motionless on the seabed several times.

[bigboywooly]

Not too sure about being totally undetectable sat on the sea bed
There are more than a couple of accounts of warships dropping DCs on what they thought were sub targets only to find out later were wrecks

[Gezur(Arbeit)]

shipwrecks are bigger and higher than uboats

[Jimbuna]

shipwrecks are bigger and higher than uboats

That may be true, but in-game your afforded no protection. The asdic (and sonar) can 'see' through small land masses. :doh:

[Sailor Steve]

Not too sure about being totally undetectable sat on the sea bed
There are more than a couple of accounts of warships dropping DCs on what they thought were sub targets only to find out later were wrecks
We also have no accounts from submariners for whom it didn't work; and with good reason.

I've related before the story of my aerodynamicist friend talking about the famous dive rate of the P-47 thunderbolt. Every time someone says "Yeah, they always got away from the Germans by out-diving them!", my friend replies "Well, except for the ones who didn't; and they ain't talking!"

[irish1958]

Sitting on the sea floor has been the death of several of my unfortunate boats. I wouldn't recommend it.

[Jimbuna]

Sitting on the sea floor has been the death of several of my unfortunate boats. I wouldn't recommend it.

All your actually doing is saving the game the bother of putting you there....forever :lol:

[STEED]

Sitting on the sea floor only makes there job more easy. ;)

[Gezur(Arbeit)]

my post on the shipwrecks was for reallife...not for Sh3, because i dont think escorts in sh3 will depthcharge shipwrecks.

[Jimbuna]

my post on the shipwrecks was for reallife...not for Sh3, because i dont think escorts in sh3 will depthcharge shipwrecks.

That's because they're no longer rendered shortly after they sink.....unless the water is quite shallow http://www.psionguild.org/forums/images/smilies/wolfsmilies/pirate.gif

[johnno74]

In real life sitting on the seabed doesn't make you invisible to sonar/ASDIC. Sonar works on the principle that when a sound wave hits something with a different density, part of the sound is reflected back. About the biggest density change possible is when the sound wave travels through a sub's pressure hull, then reaches the air trapped within.

So if you are sitting on the bottom in real life, yes you will be camoflagued to a certain degree because the sonar "pings" reflect off the denser sea floor, but a trained sonar operator can definitely pick up the much stronger reflection off your submarine. Now I don't know a hell of a lot about sonar besides the scientific principles, so I can't tell you just how easy it is to pick up a sub on the seafloor with WWII equipment, but it is certainly possible. With modern equipment it is trivial. Even a basic fish-finder would show up a submarine on the bottom as plain as daylight.

In WWII U-boats sitting on the sea-floor were NOT invisible.

[Der Teddy Bar]

There is the slight issue of oil slicks.

I have read quit a few instances where a u-boat was detected by aircraft because of a trailing oil slick. Most of these instances where of a moving u-boat in deep water well into the Atlantic ocean.

It is my understanding that the sea bed was a good hiding place when the enemy was not aware of your presence but not so affective when you were being hunted.