How do they know?

[johan_d]

Kaleuns, meine herrn,

How in earth do they know?

Lets say I am laying death still in the water, a convoy passes by, it is dark, I fire an electric torpedo, and after the impact the escorts come directly to the spot I am in.

How can they possible know from where the shot came? nobody could see it to report, they dont hear me, but pinpoint the location very well.

Johan

[GoldenRivet]

if you were not in silent running to begin with they will hear the reloading efforts started immediately after the shot.

also with a good ear into the hydrophone receiver on an escort - just right - they can in real life hear the hiss of the compressed air forcing the torpedo out of the tube. and can find you based on hearing this.

those are the only two plausible reasons i can come up with that they go to the exact position you fired from...

however i will also point out that i have fired several shots on a convoy and the escorts fan out in search patterns but never even coming close to me... this has happened several times.

[Lzs von swe]

If you hit a ship in the outer left line of the convoy the escorts will most likely start searching in that direction, 1000-2000m out. If you are still there when they get there, you are in trouble. Lesson learned, do not stay in your firing position, scope down, dive and move out of the way:up:

[UnterseeBoogeyMan]

if you recall on the weapons screen, while in port, the description said the 1st generation of torpedoes left a wake of bubbles on its way to the target. Not sure what year you started, but that could be a factor.

[nfitzsimmons]

If you hit a ship in the outer left line of the convoy the escorts will most likely start searching in that direction, 1000-2000m out. If you are still there when they get there, you are in trouble. Lesson learned, do not stay in your firing position, scope down, dive and move out of the way:up:

The modern technical term for this procedure is to "clear datum."

[GoldenRivet]

if you recall on the weapons screen, while in port, the description said the 1st generation of torpedoes left a wake of bubbles on its way to the target. Not sure what year you started, but that could be a factor.

he stated that he used the electric torpedoes that do not leave this visible wake. Only the "steamers" leave the wake. electric "eels" are quite stealthy.

also boats can report whether they were hit on the port or starboard side giving the escorts some kind of indication which side of the convoy to start looking.

[Puster Bill]

if you recall on the weapons screen, while in port, the description said the 1st generation of torpedoes left a wake of bubbles on its way to the target. Not sure what year you started, but that could be a factor.
he stated that he used the electric torpedoes that do not leave this visible wake. Only the "steamers" leave the wake. electric "eels" are quite stealthy.

also boats can report whether they were hit on the port or starboard side giving the escorts some kind of indication which side of the convoy to start looking.

Electric eels aren't *THAT* stealthy. I don't know if this is modelled in SHIII, but even an electric torpedo will have a highly distinctive high-pitched 'whine'. Any sonar guy worth his salt would hear it, and if you can hear it moving, you can get a pretty good guess as to where it came from.

True, they don't leave a wake, but they still make noise.

Clearing the datum is kind of tricky: You have to be reasonably close to have a decent chance of hitting the target, but if you move at any appreciable speed the escorts will hear you.

The trick is to not wait around to see the results of your marksmanship. After the first couple or 3 years of the war, that is just plain suicide. Go deep, go silent, and don't move in a straight line, but a very shallow turn (like 5 degrees rudder). Try to keep your bow or stern pointed at the escort that is the biggest threat.

The biggest threat isn't always the closest, either. A favorite tactic later in the war is for one escort to fix your position and have the other one do the depth charge runs.

[spork542]

There have been many situations in which I have attacked a convoy and the escorts, immediately after the torpedo impact, started speeding towards my position by the centimeter in accuracy. This is with silent running on and moving at 1kt. This occurs to me even with electric torpedoes. Indeed, if the escorts did not head after me due to the compressed air (they found me after the torpedo impacts) they would have nothing else to listen to in order to find my position so accurately. And at the range I am normally at, they can't ping me. It's lunacy, absolute lunacy.

[KeptinCranky]

you can actually hear your eels on the hydrophone, then listen for the whine of the eel to intersect the thumpa-thumpa of the merchant and if all went well....ker-foom

however, that's also what the escorts hear

[johan_d]

Thanks guys will keep that in mind, the silent running I will try the next launch. Good catch.

Johan

[Lzs von swe]

If you hit a ship in the outer left line of the convoy the escorts will most likely start searching in that direction, 1000-2000m out. If you are still there when they get there, you are in trouble. Lesson learned, do not stay in your firing position, scope down, dive and move out of the way:up:

The modern technical term for this procedure is to "clear datum."

You youngsters and your "modern" terms:rotfl:

[Jimbuna]

There have been many situations in which I have attacked a convoy and the escorts, immediately after the torpedo impact, started speeding towards my position by the centimeter in accuracy. This is with silent running on and moving at 1kt. This occurs to me even with electric torpedoes. Indeed, if the escorts did not head after me due to the compressed air (they found me after the torpedo impacts) they would have nothing else to listen to in order to find my position so accurately. And at the range I am normally at, they can't ping me. It's lunacy, absolute lunacy.

Golden Rivet more or less answers here: also boats can report whether they were hit on the port or starboard side giving the escorts some kind of indication which side of the convoy to start looking.

I'd suggest you try approaching a convoy from side on, launch at the furthest column away from your sub. You'll find that the escorts on that side of the convoy will sweep outwards looking for you whilst the escorts on your side of the convoy will sail merrily on.
The mistake a lot of people make is to fire at the nearest column whilst up close....this gives them little chance of evasion without using the electrics at high speed which means they will be heard by the escorts anyway. :arrgh!:

[Brag]

Immediately after launchig torpedoes do the wiggle-waggle. (Search for the wiggle-waggle thread). I think I have wiggle-waggle described on my webbie. :D

[Paajtor]

if you were not in silent running to begin with they will hear the reloading efforts started immediately after the shot.
If you have auto-reloading off (top-left of the weapons-management screen, I-key), there shouldn't be any reloading-sounds, right?
Or isn't this featured in SH3 (or GWX)?

Btw, in which period of the war are you sailing, Johan_d?

[Growler]

The biggest threat isn't always the closest, either. A favorite tactic later in the war is for one escort to fix your position and have the other one do the depth charge runs.

Which is exactly how US Coast Guard cutters Spencer and Duane finished off U-175 on Apr. 17, 1943. Duane fixed the U-boat's position, and Spencer did the DC run.

There were only seven of the Treasury-class cutters built for the USCG in the late thirties. One, WPG-34, the Alexander Hamilton, was torpedoed by U-132 on 29 January, 1942, and sank sometime during the night of 30 January. Two remain afloat today Ingham (WPG/WHEC-35), and Taney (WPG/WHEC-37). Ingham is at Patriot's Point in South Carolina, and Taney is at Baltimore's Inner Harbor, Pier 5. I wish I was a good enough modeller to try adding the Treasury-class ships to the game, as these are classic CGG cutter/escorts.

I worked on the Taney last summer, and had a lot of time to talk with former members of her crew, as well as guys who served on her sister ships. The Treasury-class (also known as the Secretary-class, or simply the 327's) had almost 50 years of continual service from their creation in the late 30's until decomissioning in the eighties. Taney was a Pearl Harbor survivor, went on to run a couple of convoys in the Atlantic, was the amphibious command ship for the invasion of Okinawa. In 1985, less than a year before decommissioning, she hauled in 160 tons of marijuana in a bust off the coast of Virginia. Not bad for a 50 year old ship!

[Sailor Steve]

If you hit a ship in the outer left line of the convoy the escorts will most likely start searching in that direction, 1000-2000m out. If you are still there when they get there, you are in trouble. Lesson learned, do not stay in your firing position, scope down, dive and move out of the way:up:

The modern technical term for this procedure is to "clear datum."

You youngsters and your "modern" terms:rotfl:
Gee, and I always thought the correct technical term was "Run away! Run away!"

[Brag]

Just finished an attack on a heavily escorted convoy, at least 4 escorts. Hit 2 large freighters and a large tanker (approx 35K tonnes). Wiggled waggled, the escorts, though numerous combed the area but never found me. :smug: