Ticonderoga wrote:
Post war USN ships had a device called Prairie Masker that was used to "quiet down" the nose of the props. It consisted of a series of holes on the side of the ship (may have been on the propellers too, can't remember) that bled compressed air down the side of the hull and past the props. I don't know how successful this was.
Cavitation (due high prop speed) occurs when the water literally boils around the trailing edge of the prop blades. As the gas bubbles implode they of course make a lovey sound that the sludgmariners love to hear. I doubt very much that any "shaping" of the underwater hull would do much to silence the acoustic signature of the ship. I would suggest that this would be done to improve the hydrodynamic performance of the hull and the efficiency of the prop system.
Submarine props are typically very large compared to surface ships and they have a very unique scimitar type design, all designed to reduce the incidence of cavitation, even at relatively high speed.
Ship borne towed array sonar or VDS are typically on very long lines from the ship so as to reduce the impact of interference from the ship its self.
The other interesting thing here is that the Kirov class are nuclear, hence they use boilers and have rather heavy duty cooling pumps to manage the reactor core heat generation. These pumps and the boilers themselves, would give these ships a very unique set of acoustic signature lines at some very discrete frequencies, very hard to disguise and again, music to the ears of a sludgemariner.
Andrew
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Supposedly the soviets perfected a electronic system that picks up ship's noise in real time, actively and electronically generates an out-of-phase sound pattern, and use that sound to ecancel out the ship's noise.
So the point is not to diminish the noise at the source, or block the noise from reaching the water, but canceling the noise once it is in the water.
Udaloy class supposedly has the noise cancellation system installed. Perhaps one or more of the kirovs do as well, since kirovs have essentially the same antisubmarine capabilities as the specialized udaloys.