thermal layer

rawghi · 05-08-07, 05:41 AM

Hi to all,
I haven't understood how thermal layer function and ho wto identify them...
in short... what is a thermal layer???!?

Thank you very much

FooFighters · 05-08-07, 05:55 AM

Quote:

Originally Posted by rawghi

Hi to all,
I haven't understood how thermal layer function and ho wto identify them...
in short... what is a thermal layer???!?

Thank you very much

I am not 100% sure.. but I thought thermal layer is a layer between the cold and warm water in an ocean. I'ts difficult to detect a sub in this layer because of turbulance. The depth of the layer differs.. so it's hard to tell how deep it is.

Again.. I am not 100% sure, but this is what I think it is.
I'll try to find some info on it.

TheVillagePeople · 05-08-07, 05:55 AM

At one point my crew said "Passing thermal layer" like 4 times , I think it was when I was surfacing.

rawghi · 05-08-07, 05:59 AM

Thank you both

TDK1044 · 05-08-07, 06:15 AM

Basically, the sunlight entering the ocean is absorbed near the surface. This surface water mixes with the cooler, deep waters as the wind and currents stir the waves. The surface layer therefore has pretty much a uniform temperature.

The temperature of seawater immediately below the top layer changes relative to depth. Each temperature change event is a thermal layer.

EMAPhil · 05-08-07, 07:00 AM

http://navsci.berkeley.edu/ns401/NS4...ound%20mjh.ppt
Some very good stuff here. Just Google on: Thermal layer sonar asdic
You will find tons of it.

(ASDIC was the British term used when they invented it at the end of WW1, don't flame me I haven't time to check the dates)

SteamWake · 05-08-07, 08:05 AM

The psychic crew member will announce to you when that layer is being passed.

In real life a gizmo was used to measure the water temprature outside the ship. When there was a dramatic shift 10 to 20 degrees it could be assumed that a thermal layer had been passed.

Wether or not these gizmos were available for fleet boats is another topic for discussion.

I personally have no idea.

The layers are modeled in the game to some degree but basically just lowers your sound and sonar return signatures.

FooFighters · 05-08-07, 08:06 AM

Quote:

Originally Posted by TDK1044

Basically, the sunlight entering the ocean is absorbed near the surface. This surface water mixes with the cooler, deep waters as the wind and currents stir the waves. The surface layer therefore has pretty much a uniform temperature.

The temperature of seawater immediately below the top layer changes relative to depth. Each temperature change event is a thermal layer.

I was on the right track :rotfl: :rotfl: :rotfl:

ReallyDedPoet · 05-08-07, 08:32 AM

This is a mod regarding thermal layers:

http://www.subsim.com/radioroom/showthread.php?t=110559

RDP

TripleDaddy · 05-08-07, 12:05 PM

Depending on the quality of the destroyer crews and the destroyer class, running below the thermal layer makes you neigh well invisible.

TheSatyr · 05-08-07, 03:27 PM

A device came into usage on Fleet Boats around 1943 (I think) to be able to detect when a sub crossed a thermal layer. So yeah,they were able to detect them. I think it was also used to tell how deep the thermal layer was.

SteamWake · 05-08-07, 03:37 PM

Quote:

Originally Posted by TripleDaddy

Depending on the quality of the destroyer crews and the destroyer class, running below the thermal layer makes you neigh well invisible.

I wouldent count on this absolutly tough.

I have been picked up through a thermal in silent running at 2 knots.

AVGWarhawk · 05-08-07, 03:43 PM

As I understand it the water temp in varying degrees creates a layer(density) that vessels sensors have trouble getting through or just bounce back.

In the game, it reduces sensors on the DD looking for you. Not an absolute as I have witnessed. You still can be found.

vindex · 05-08-07, 09:58 PM

My understanding is that the temperature of the water affects the way sound travels. So when a sound wave encounters a shift in temperates between layers, the wave is either defracted or dispersed or both. So whether they are pinging you or listening for your engine, the feedback will be distorted, resulting in either no contact or an incorrect position.

Is there anyone who can confirm this?

Chock · 05-08-07, 10:10 PM

That's correct Vindex. Basically you can think of it as being similar to the effect of light passing through a prism.

However, it's probably more accurate to say the sound 'can' be distorted, rather than it 'will' be distorted. How much the distortion will be depends on the temperature variance, as well as other factors such as the salinity of the water. In SH4, the effect is perhaps a little too guaranteed, but all the same, it's nice that the effect is now actually in Silent Hunter.

If you want to read up on thermal layers, there's quite a bit about it on the sub Command and Dangerous Waters subsim forums, since thermal layers feature heavily in those two sims.

05-08-07, 05:41 AM	#1
rawghi Swabbie Join Date: Apr 2007 Location: Milan Posts: 11 Downloads: 3 Uploads: 0	thermal layer Hi to all, I haven't understood how thermal layer function and ho wto identify them... in short... what is a thermal layer???!? Thank you very much __________________

05-08-07, 05:59 AM	#4
rawghi Swabbie Join Date: Apr 2007 Location: Milan Posts: 11 Downloads: 3 Uploads: 0	Thank you both __________________

05-08-07, 08:32 AM	#9
ReallyDedPoet Canadian Wolf Join Date: Jul 2006 Location: The one and only East Coast Posts: 10,776 Downloads: 946 Uploads: 5	This is a mod regarding thermal layers: http://www.subsim.com/radioroom/showthread.php?t=110559 RDP __________________ Back in the Day

05-08-07, 03:43 PM	#13
AVGWarhawk Lucky Jack Join Date: Jun 2005 Location: In a 1954 Buick. Posts: 27,343 Downloads: 90 Uploads: 0	As I understand it the water temp in varying degrees creates a layer(density) that vessels sensors have trouble getting through or just bounce back. In the game, it reduces sensors on the DD looking for you. Not an absolute as I have witnessed. You still can be found. __________________ “You're painfully alive in a drugged and dying culture.” ― Richard Yates, Revolutionary Road

05-08-07, 05:55 AM	#3
TheVillagePeople Swabbie Join Date: May 2007 Posts: 14 Downloads: 0 Uploads: 0	At one point my crew said "Passing thermal layer" like 4 times , I think it was when I was surfacing.

05-08-07, 06:15 AM	#5
TDK1044 Ocean Warrior Join Date: Mar 2005 Location: Georgia, USA Posts: 2,674 Downloads: 25 Uploads: 0	Basically, the sunlight entering the ocean is absorbed near the surface. This surface water mixes with the cooler, deep waters as the wind and currents stir the waves. The surface layer therefore has pretty much a uniform temperature. The temperature of seawater immediately below the top layer changes relative to depth. Each temperature change event is a thermal layer.

05-08-07, 07:00 AM	#6
EMAPhil Swabbie Join Date: Apr 2007 Location: Derby UK Posts: 13 Downloads: 0 Uploads: 0	http://navsci.berkeley.edu/ns401/NS4...ound%20mjh.ppt Some very good stuff here. Just Google on: Thermal layer sonar asdic You will find tons of it. (ASDIC was the British term used when they invented it at the end of WW1, don't flame me I haven't time to check the dates)

05-08-07, 08:05 AM	#7
SteamWake Rear Admiral Join Date: Mar 2005 Posts: 13,224 Downloads: 5 Uploads: 0	The psychic crew member will announce to you when that layer is being passed. In real life a gizmo was used to measure the water temprature outside the ship. When there was a dramatic shift 10 to 20 degrees it could be assumed that a thermal layer had been passed. Wether or not these gizmos were available for fleet boats is another topic for discussion. I personally have no idea. The layers are modeled in the game to some degree but basically just lowers your sound and sonar return signatures.

05-08-07, 12:05 PM	#10
TripleDaddy A-ganger Join Date: Apr 2007 Location: Charlotte Posts: 76 Downloads: 1 Uploads: 0	Depending on the quality of the destroyer crews and the destroyer class, running below the thermal layer makes you neigh well invisible.

05-08-07, 03:27 PM	#11
TheSatyr Captain Join Date: Apr 2002 Posts: 545 Downloads: 0 Uploads: 0	A device came into usage on Fleet Boats around 1943 (I think) to be able to detect when a sub crossed a thermal layer. So yeah,they were able to detect them. I think it was also used to tell how deep the thermal layer was.

05-08-07, 09:58 PM	#14
vindex Planesman Join Date: Apr 2007 Posts: 192 Downloads: 17 Uploads: 0	My understanding is that the temperature of the water affects the way sound travels. So when a sound wave encounters a shift in temperates between layers, the wave is either defracted or dispersed or both. So whether they are pinging you or listening for your engine, the feedback will be distorted, resulting in either no contact or an incorrect position. Is there anyone who can confirm this?

05-08-07, 10:10 PM	#15
Chock Sea Lord Join Date: May 2005 Location: Under a thermal layer in chilly Olde England Posts: 1,842 Downloads: 0 Uploads: 0	That's correct Vindex. Basically you can think of it as being similar to the effect of light passing through a prism. However, it's probably more accurate to say the sound 'can' be distorted, rather than it 'will' be distorted. How much the distortion will be depends on the temperature variance, as well as other factors such as the salinity of the water. In SH4, the effect is perhaps a little too guaranteed, but all the same, it's nice that the effect is now actually in Silent Hunter. If you want to read up on thermal layers, there's quite a bit about it on the sub Command and Dangerous Waters subsim forums, since thermal layers feature heavily in those two sims.