Enemy sonar at medium speeds?

[E.B. Fluckey]

Last night it seems I was detected by enemy sonar at a range of 5000 meters. The enemy vessel was traveling at 16-18 knots so I assumed they would have a hard time hearing me. Does it seem odd to be detected at this range?

Here are the details:

Enemy speed: 16-18 knots
Enemy range: ~5000 meters
Sub: Type II
Sub Depth: ~13 meters
Sub Speed: Ahead Standard (4-5 knots)
Date: Dec '39
Where: North Sea, shallow water
Mods: GWX

Thanks!

[AS]

Well, historically they couldn´t hear you when faster than 12kt, especially not at 5000m. Maybe they spotted your scope???

AS

[Koinonos]

With no periscope raised, 20 meters below the surface, all stop, and silent running. I've been detected by DD's, DE's, and even Armed Trawlers in from 1000-1500 meters when they are running 12-18 knots even in the early years (1939 - 1940)?? :shifty:

I was thinking about creating a post on this subject when I noticed someone else was wondering the same thing. It's a head scratcher to me (is it a bug, or a compromise the GWX team had to make to get another area of ASW to work better?) I realize it is probably a variable that may affect other functions, but is there a variable in SH3 that allows the reducing of surface ship ASW detection the faster they go?

Their detection does appear to become more sensitive when they are cruising around at 4-7 knots trying to find me, so in gameplay their ability to detect feels right at slow speeds when they are actively searching for you. If I had a variable knob for this I would make them about 20% harder of hearing @12knots and about 40% harder of hearing @18 knots.

When I ponder this I can't help but think of the Admiral in The Hunt for Red October's line about Surface ships at medium to high speed and their detection capabilities - "At that speed they could run over my daughter's stereo and not hear it".. :D

[E.B. Fluckey]

There is a slim posibility they spotted my scope. However I only popped it up for a short time, barely above water, and at slow speed (3 knots).

I did pop it up at 5 knots when the track showed the ship was suddenly heading straight for me :o

I may test this a bit if I can set up a scenario with some set conditions.

Anyone know if the game models reduced passive sonar effectiveness at medium-high speeds? Perhaps it something I can adjust myself.

[E.B. Fluckey]

I'll also add that after I realized I was detected I switched to silent running/silent speed (1.5 knots) and the ship in question (plus friends he called in to join the hunt) failed to find me even when they passed within 400 meters of my u-boat. No ASDIC I assume :cool:

[robj250]

I'm not sure whether this is a good place to mention anything about being spotted. But it sure would be interesting to know why subs are detected in the early parts of the war 39 - 40, when the sub is travelling on the surface at a distance of 5000m and the sub doing standard speed. I suppose it is the white water from the wake that the sub leaves. I can certainly understand this if the spotter was an aircraft. But does a surface ship "ALWAYS" spot you, after all, the lookouts in RL are only human, and unless they have radar??? Now what about during the night??? The earth is not flat and we do not fall off the edge if we go so far. There is a horizon, and I forget the distance of surface to surface distance for, lets say, two Frigates, now let's drop it down for a sub and a Frigate.

[Sailor Steve]

5000 meters is 5 kilometers, which is only 3.1 miles. I was unhappy when an escort in NYGM spotted me at 7000 meters, but 5000 doesn't seem unreasonable.

Now that I think of it, 7000 meters is only 4.2 miles. Someone recently posted that the horizon from the conning tower of a sub is around 8 miles, and ships can be seen a lot further away than that.

[Albrecht Von Hesse]

My fifth patrol, in mid-January 1941, I was at 14 meters, doing 1 knot, as a Black Swan was slowly moving towards me. It was the lead escort of a convoy, I'd been in position for 1 hour at 1 knot (so it's not as if they had advanced warning I was even in the vicinity).

I didn't position myself quite where I'd wanted: I was pointing directly towards the convoy track, which meant it (and the frigate) was heading straight towards me. Which is what I wanted, except I'd wanted to be positioned so the frigate would pass to one side of me around 1.000 - 1.500 meters off to the side. Instead it was closing to pass within only a couple hundred meters.

While still at 15 meters, scope never being raised once the frigate had closed to 2.500 meters, and still at 1 knot, running silent, I was tracking it manually on the hydrophones. When it was approximately 400 meters away I suddenly heard its screws crank way the heck up. Then, 5 seconds later, it started actively pinging.

I'd dearly love to know what reason it had to detect me :( :x

[robj250]

5000 meters is 5 kilometers, which is only 3.1 miles. I was unhappy when an escort in NYGM spotted me at 7000 meters, but 5000 doesn't seem unreasonable.

Now that I think of it, 7000 meters is only 4.2 miles. Someone recently posted that the horizon from the conning tower of a sub is around 8 miles, and ships can be seen a lot further away than that.

Thanks Steve
I just happened to remember that in the original Silent Hunter, I has developed a charting board based on the radar of the US subs and the maximum distance for radar to pick up a convoy or ship was 17 nautical miles (of course - depending on the height of the radar itself)

[Trygvasson]

... But does a surface ship "ALWAYS" spot you, after all, the lookouts in RL are only human, and unless they have radar??? Now what about during the night??? The earth is not flat and we do not fall off the edge if we go so far. There is a horizon, and I forget the distance of surface to surface distance for, lets say, two Frigates, now let's drop it down for a sub and a Frigate.

They certainly don't always spot me, I just had a destroyer pass my bows at 2000m, and I was running flank speed. I think I used up a big chunk of luck there. GWX seems to have a great variability of detection levels. A sleepy watchman or a sharp-eyed one seems to make a difference measured in thousands of meters.

A note of interest: knowing the effect of the curvature of the earth, most destroyer lookouts were situated as high as possible, to get maximum horizon. However, one unintended side effect of thi was that the profile a sub on the surface and close to the destroyer would not be outlined against the sky, but only to the sea, making it very hard to spot.

[Trygvasson]

.... still at 1 knot, running silent, I was tracking it manually on the hydrophones. When it was approximately 400 meters away I suddenly heard its screws crank way the heck up. Then, 5 seconds later, it started actively pinging.

I'd dearly love to know what reason it had to detect me :( :x

Sounds like an Elite hydrophoneman heard your 1 knots. How do you manage to run at 1 knot anyway? were you maneuvering at Dead Slow? Any maneuvering or speed increases your audio signature, you are advised by BDU Lehmann that the only real silent running is a full stop. :-?

[robj250]

Last night it seems I was detected by enemy sonar at a range of 5000 meters. The enemy vessel was traveling at 16-18 knots so I assumed they would have a hard time hearing me. Does it seem odd to be detected at this range?

Here are the details:

Enemy speed: 16-18 knots
Enemy range: ~5000 meters
Sub: Type II
Sub Depth: ~13 meters
Sub Speed: Ahead Standard (4-5 knots)
Date: Dec '39
Where: North Sea, shallow water
Mods: GWX

Thanks!

Haven't you heard Kaleun Fluckey. In GWX, not matter what year it is during the war, you haven't got a chance because the DDs are very elite and the lookouts can see for miles. And when they find you, they can hear you whisper. :p