Less than 18knots?

[Linton]

Does it matter because you will sound like a train anyway at those sort of speeds in shallow water!

Hello, Kapitan and Linton

It all works on the basis of hydro dynamics
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But torpedoes can run more than 18knots in shallow water.

Does it matter...
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When the torpedoes chase around you, it does matter.

[Linton]

U-161 what is your definition of shallow water?To avoid cavitating your speed should be no more than the square root of your depth.
If you are being quiet=stealthy then torpedoes shouldn't be chasing you!
Compare the size of a torpedo and the flow of water around it to that of a submarine.An adcap is 21 inches wide-a submarine is 34 feet.In the submarine you are disturbing a much greater body of water and this is obviously interacting with the seabed causing a disturbed flow.This in turn produces drag around the form of the submarine.
http://www.dsto.defence.gov.au/publi...TO-TR-1622.pdf

Originally Posted by Linton

U-161 what is your definition of shallow water?

Depth less than 200 feet.

Originally Posted by Linton

To avoid cavitating your speed should be no more than the square root of your depth.

Thank you for let me know that.

Originally Posted by Linton

Compare the size of a torpedo and the flow of water around it to that of a submarine.An adcap is 21 inches wide-a submarine is 34 feet.In the submarine you are disturbing a much greater body of water and this is obviously interacting with the seabed causing a disturbed flow.This in turn produces drag around the form of the submarine.

I believe the same situation will happen to the surface ship. But I have never heard that surface ship is draged by the disturbed flow caused by seabed. Besides, if the distance between seabed and surface is several thousand feet, it is impossible to cause any disturbed flow.
Maybe sub builder has decided to limit the speed because flank running in shallow water for torpedo evasion will cause more torpedo attack by enemy and easily damaged by mines.