Clear something up about thermal layers

[SteamWake]

I have always been of the belief that when your hiding beneath a thermal layer it is best to do so only a few meters below the layer.

That if you go deeper than that it is easier to pick you up

In other words therma layer at 140 feet it would be harder to detect you at 150 feet than if you were at 210 feet.

True or false?

and is this modeled in the game?

[Rockin Robbins]

No, I always figure the further you are away, and that includes vertical distance, the fainter your sound would be. My fighting style is to stay as close to the surface as I can, however, so I usually duck just beneath the layer. I want to be able to quickly pop up to periscope depth with intent to do great harm. A sub at 1000' with its tail between its legs is no danger to anyone but its crew. Be dangerous, I say!

[SteamWake]

Well when you have 4 angry DD's shooting and scooting about all you can to is to try to slink away with your tail between your legs.

[Pisces]

As far as I know nothing like a thermal layer is moddeled into the game. However, I think Sh3 Commander does have the ability of adjusting (randomly) some depth hardcap that makes you undetectable by sound below some depth. So it sort of models a hard thermal layer. But far from realistic. (oops, I forgot I posted this in Sh4 section, never mind that)

Something else. Dr.Sid (a user of this forum) made a little simulation program to show how soundrays get bend around and reflected underwater based on a soundspeed profile.

http://www.subsim.com/radioroom/showthread.php?t=120487

You should know a bit about what soundlayers are and how hydroacoustics work to really make sense out of it. If you create an 'increasing soundspeed' curve just below the waterlevel, and a 'slowing down soundspeed' below some desired layerdepth you can indeed see that sound emitted above the layer stays there. And a sub right under the layer would hardly receive/perceive that sound. Load the "surface duct" sound profile through the SSP button and test different sound source depths (i.e. 10 m) You'll notice a pretty dark area under the layer, but not if you get too close. Then a DD could stil get a direct ping return path. Similarly the sound that you emit below the layer (sound source depth 110m) is alot fainter above it when far away. But if the DD is on top of you there also is a straight path. Soundlayers are not mirrors reflecting the sounds in the other direction. It depends on the angle if the sound penetrates it.

[G2B]

I'm not sure if the depth matters when your below the thermal layer, What usually works for me is doing a fast steep dive (full or flank) until I hit the layer. Cut to slow (or silent if I still have a couple fish loaded) and do a hard turn and level out about 50 feet under the layer. Then I adjust the course on whats going on above, sneek away. If there's only a couple escorts I'll come up slow and try a shot with the aft tubes.

I wonder if one was just above the layer doing full back then dropped below the layer and went to silent running ahead, if this would mess with the AI

[Ducimus]

Originally Posted by SteamWake

I have always been of the belief that when your hiding beneath a thermal layer it is best to do so only a few meters below the layer.

That if you go deeper than that it is easier to pick you up

In other words therma layer at 140 feet it would be harder to detect you at 150 feet than if you were at 210 feet.

True or false?

and is this modeled in the game?

I can't give you a real life answer, but i can give you a SH4 answer.

False.

In SH4 terms, A thermal layer is boolean. Your either above it, or your not. The layer itself is merely a reduction of the signal strength received by the pinging (or listening) escort. So that aside, geometrically speaking, it's still best to go as deep as you can to get under the sonar beam or minimize the time the sonar beam is on you.