Sauragnmon wrote:
Why do I have a feeling it's not so much a dipping sonar as a towed array - remember, the original design for the Kirov Class was a heavy ASW platform in addition to other equipment.
Nearly right. The correct nomenclature (in NATO at least) is Variable Depth Sonar (VDS). Typically the ship will have to slow, almost to a stop to deploy the body. Once in the water speed can be slowly increased, but top speed is severely restricted a) because of the nature of the tow and b) the sonar will not perform properly at much above 15 knots or so if you want to hear anything on the sonar. Maneuvering is also limited by the tow. Recovery also presents problems as the ship must almost stop to make the final recovery.
It is possible that one would set the VDS to the "in layer depth" and go active simply to deny the submariner that piece of ocean. It is also possible that the hull mounted sonar(s), operating in listen only mode, would hear any echoes generated by the VDS.
Remember the scene where the good guys figured out that the ruskies were driving Ramius to the hunters by "banging on everything they have"
Towed arrays are typically deployed from submarines. They are very very long cables fitted with an "array" of sonar transducers. These towed arrays only operate in listen mode. But due to their length, it is possible compute range without going active. the long array provides a good triangulation base. The "one ping only !" is a very rare thing in deed for a submariner to do.
The term "dipping Sonar" is typically used for the sonar that is deployed on the end of a cable from helicopters.
Andrew
PS convention says that the best weapon to fight a submarine with is another submarine, second best three or more Helicopters. There is not third best. Sending surface ships to prosecute a modern submarine has a very low rate of return.