Tip on hiding from DD's sonar (Real Life)

[MaxT.dk]

Differences in seawater temperature help subs hide out. By lurking right below the thermocline (PASSING THERMAL LAYER...), the layer between the surface and deeper waters, subs can avoid some sonar pings from ships or aircraft trying to detect them. That's because sound waves distort when passing through varying water temperatures.



Hmm, I wonder if this trick works in SH4... :hmm:

[General Tso]

Yes it works very well.

[General Tso]

Oops, I just noticed the icons after your last sentence. I guess you were'nt asking a question.

[nomad_delta]

For the 'thermal layer' effect to help, does one have to hide right below it (that is, stop diving immediately after passing thermal layer) or just anywhere below it, including much deeper?

Also does being below the thermal layer help with hiding from just passive sonar/hydrophones -- or does it help hide from active sonar (pinging) too?

nomad_delta

[John Channing]

Anywhere below it and it helps with both.

But it is not a "cloaking device". You still have to be slow and stealthy.

JCC

[V.C. Sniper]

The deeper the better

[DirtyHarry3033]

Like JCC said, anywhere below the layer helps but you can still be detected by sonar.

The layer is an "interface" between warm water (close to the surface) and cold water (well below the surface).

Picture yourself in a fishing boat on a crystal-clear lake, you look down thru the surface of the lake and spot a fish just below the surface. You take a frog gig and attempt to spear the fish, aiming directly at what you see. Well, you will miss!!!

Why? Well the "interface" between the air and the water refracts the light rays, they are "bent" so that the target you are looking at is not where it appears to be from your point of view. You can still see it, but it is not where your senses tell you it "is".

If your fish was lying on the beach, above the surface of the water, it would be no problem to spear him, right?

The thermocline does the same thing, except with sound waves. When you get below the layer, the enemy still knows you're there but it's much harder for him to pinpoint your location since his active sonar is refracting off the layer. Or, if he's listening passively, your sound emissions are also refracting off the layer.

In either case, the sonar return received by the DD will appear to be coming from someplace that it's not. And as V.C. Sniper said, the deeper below the layer you are, the more the return gets refracted. Once the DD's find me, I'll generally dive to 400+ feet, go silent and creep at 1-2 kts. They're dropping DC's in my general area because they have a rough idea where I am but it's rare for one to hit close enough to damage me...

However, make too much noise and you'll eventually be pinpointed The layer is not an invisibility shield!

DH

[Go4It]

Playing with Kakemanns Improved Escorts mod, was hounded by 4 elite DD after sinking 2 ocean liners, couldn't lose them for 2 hours, even at the deepest depth I dared go they still found me. I said %$%$#@#@ this an ordered all stop, with in 15 minutes all DD were gone. I tried this other times an it works. Done know if it's Kakemanns Improved Escorts mod or a bug in SH4

[the_belgian]

Originally Posted by MaxT.dk

Tip on hiding from DD's sonar (Real Life) :hmm:

Stay out of the water :rotfl: :rotfl: :rotfl:

[CaptBC]

Once below a thermal layer go silent (if you haven't already) and order the engine room to make rotations for 1 or 2 (no more than 2) knots. I use 1 knot and slowly slink away from those pesky destroyers!

CaptBC

[nomad_delta]

I'm running Trigger Maru 1.2 and I think Ducimus made the DD's a lot smarter/more aggressive/difficult to evade. Even when I drop to 1-2 knots and max out my depth and try to slink away they always seem to find me and depth charge me repeatedly anyway.

I've discovered that even though my sonar man is nearly entirely deaf and doesn't tell me anything useful at all, if I listen through the hydrophones myself I can in fact hear the 'splashes' of the depth charges hitting the water. (Actually a couple times I took a peek through the observation periscope and actually saw the depth charges dropping next to me.

So I've taken to going to flank speed immediately as soon as I hear the splashes (if I'm lucky enough to be manning the hydrophones and pointing them in the right direction at the right time, that is) and keeping it on for about 6-7 seconds, then dropping to 1/3 or all stop to drift along.

The DD's are relentless though, and keep going straight over me with active sonar and dropping more depth charges, so I just keep repeating the same process and making 45 degree turns now and then... with any luck after 15-20 depth charge attempts they give up and go back to their convoy. Or more likely they get lucky and blow me to bits.

It's nerve-wracking, lemme tell ya.

nomad_delta

[MaxT.dk]

Hide under one of the merchants, or just just behind it, works here and DDs can't depthcharge you because the merchant is in the way

[starvingartist507]

according to the numbers in the data files:

if below the thermal layer, the hydrophone signal is reduced to 33% and the active sonar signal is reduced to 20%. so dropping below the thermal layer reduces your sub profile by around 70% on both active and passive sonar.

Seems to me that once I get below thermal, in most cases I can just go silent and sneak away on a constant heading. I guess this is why. That doesnt seem wrong, and it makes shalow seas even more dangerous.

Originally Posted by nomad_delta

I've discovered that even though my sonar man is nearly entirely deaf and doesn't tell me anything useful at all, if I listen through the hydrophones myself I can in fact hear the 'splashes' of the depth charges hitting the water. (Actually a couple times I took a peek through the observation periscope and actually saw the depth charges dropping next to me.

There is a whole other thread about the sonar man and his failures. To summarize: he is suppsed to warn you of a depth charge attack, of a DD successfully pinging you, and of a DD on a direct attack run.

[SteamWake]

Originally Posted by MaxT.dk

subs can avoid some sonar pings from ships or aircraft

Hrm...:hmm:

Sorry just having some fun.