From: Fast-Eddie Felson <JMARTTILA@finabo.abo.fi>
Subject: Re: Discussion Of Shallow Water ASW
Organization: Turku School of Economics
Date: Fri, 13 Nov 1992 17:42:44 GMT


From Fast-Eddie Felson <JMARTTILA@finabo.abo.fi>

   From: bphdarcy@ubvmsb.cc.buffalo.edu (Sean J. Roc D'Arcy)
>(along with a few "attemped" computer simulations) make shallow water sonar
>performance to be nill.  While the ability to use long array devices and
>some convergence zones may be lost, I still wouldn't say that sonar
>performance is "severely degraded."
 
Using long array devices for passive sub detection is possible and even
effective. The convergence zones are just one little detail. Towed array
sonar allows you to listen to the noises the sub makes instead of you own
engines and also peek under the thermal layers (there are such things in
shallow water too O:).
 
>In shallow water other ASW devices besides sonar excell.  IR and actual
>visual spotting come to mind.  MAD should still retain most if not all of
>its effectiveness.  Also, I would think surface wakes produced by the
>submerged boat would be much more prominant.
 
In peacetime situations passive acoustic detection is the most important,
because MAD, IR and other clerical methods have a very limited range and
thus are not suitable for controlling large areas. Passive acoustic
methods also require much less resourses. The other methods (mainly active
sonar) are more suitable for exact target positioning and fire-control.
 
>I think one of the major problems in shallow water ASW is the performance
>of ASW torpedoes.    How well would a Mk-46 fare in a shallow water
>situation?  In many shallow water situations depth charges might be more
>effective.
 
It depends on the situation. If the sub is hiding close to seabottom and
the bottom is rough causing a lot of false echoes a depth charge would be
the right choise. However, if the sub is moving it's a decent target for
a torpedo almost like in any other environment. As much as I know the
Swedes have recently aquired new torpedoes to be used in shallow water so
at least they believe it works O:)
 
>Also, mentioned, was the opinion that Diesel Electric Boats have a great
>edge over Nuclear Boats in shallow or coastal water operations.  While a
>well designed DE boat is harder to find that the average nuclear sub, they
>do have to give themselves away by snorkling sooner or later.  Also, no
>modern DE boat that I know of can cut over 20 knots.  A submerged approach
>to a modern container ship going into or out of port would be awfully
>difficult.
>I can't see tracking an Iranian Kilo as being a major operation in the
>Persian Gulf.
 
First I have to point out that no DE submarine is made to pursue its target,
but to wait stationary and silent on the seabottom. DE submarines fit well
in this kind of tactics - after turning off the engines they are practically
invisible for passive sonar and due to their small size they are also a very
small active sonar or MAD target.
Nuclear submarines can't just like that turn off their reactor since it
takes time to turn it on. They are also much larger and hard to manoevre in
tight spaces.

	JM

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