Effects of Depth on Sonar

[MBot]

Hello everyone
I haven't been here for years, perhaps one or two remember me from past Sub Command (and SCX) times. Yesterday I played Dangerous Waters again and it was great fun!

Now I wondered about sonar performance and depth, because frankly I can't remember how that worked in-game. How does your own depth and the depth of your targets affects detectabilities (both ways). Does depth actualy matters at all? Of course disregarding the obvious layer effects and surface noise.

What are the best depths to detect ships and subs at various depths (for each SSP)? What are the best depths to stay undedected?
And while surface noise will degrade own sonar performance at shallow depth, will it actualy cover my ownship noise?

In a enviornment without layer, will it actualy matter wether I drive at 400 or 1200ft (in game)?

[Dr.Sid]

My tests showed that besides the layer effects and surface noise, depth has no effect. It's 2D problem. Depth is only used to detect on what side of the layer you are.

All the results are here:
http://www.subsim.com/radioroom/showthread.php?t=117814

[MBot]

Thanks, fascinating read.

[Molon Labe]

http://www.subsim.com/radioroom/showthread.php?t=124973

Sonoboy's tests showed a link between detecting platform depth and detection range, when the contact was at the surface and the detecting platform was below the layer in a surface duct SSP. My interpretation of his data is that DW increases modeled transmission loss at higher velocity points on the SSP. I doubt this is only applicable to cross-layer detections.

I have accidentally attributed this data to Dr. Sid in the past, so I apologize to Sonoboy.

EDIT: I can't say I fully understand Dr. Sid's data on the shadow zone (the half on the SNR vs range is simple enough though) but my best guess is that it shows a "longer" shadow zone at depths closer to the layer--that the shadow zone extends closer to the detecting platfrom at shallower depths. That is completely consistent with Sonoboy's data showing a significant correlation between depth and detection range.

[Dr.Sid]

Yes .. the shape of the front 'edge' of the shadow zone can be seen on my data too, but not clearly. Sonobuoy made it clear.
But this only extends the layer mechanism a bit. And it is shadow zone SHAPE alone. It does not affect transmittion loss. It stays constant, until you enter shadow zone, then it becomes zero.
Also the front slope of the shado zone is quite steep, I doubt it could be used much.

[Molon Labe]

Originally Posted by Dr.Sid

Yes .. the shape of the front 'edge' of the shadow zone can be seen on my data too, but not clearly. Sonobuoy made it clear.
But this only extends the layer mechanism a bit. And it is shadow zone SHAPE alone. It does not affect transmittion loss. It stays constant, until you enter shadow zone, then it becomes zero.
Also the front slope of the shado zone is quite steep, I doubt it could be used much.

I've been applying it to active sonar evasion over the last few months, and found that it can make the difference between getting in range for a USET shot or having a ton of ASROCs shot at you.