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Well, no one has tried to sneak a sub up to a cruiser in about 60 ....

What about all those naval war games the NAVO. I believe durring those games, the submarines proved their ability to remain hidden in deep waters.

What about the flolowing idea, give deep waters a low visibility bonus, this would allow submarines in those waters to ramain hidden much better.

I performed a little test to look if this works, at it turns it does. Subs suddenly become twise as hard to spot in deep oceaan water as submarines in shallow water (near the cost) which quite realistic

:lol: Am I the only one voted No. Course I don't like the sentence after No but oh well. I like the subs the way they are. If they were even more stealthy I be losing alot of ships to them.

radars 1 Lockheed Martin AEGIS (SPY-1D) multi-function
phased array
1 AN/SPS-67(V)4 surface search
fire control 1 AESN RAN-30L/X Meroka fire control
2 Raytheon AN/SPG-62 fire control
2 Mk 99 target illumination
1 Faba DORNA K-band radar/optronic gunfire control
1 Thales SIRUS infrared search and track system
sonars 1 ENOSA-Raytheon DE-1160LF (I) hull-mounted
medium-frequency

Propulsion:
main 1 CAS-48 pressurized water reactor;
2 3,950 kW turboalternator sets,
1 electric motor; 9,500 total shp;
1 shaft
auxiliary 1 electric motor driven by batteries powered
by 1 SEMT-PIELSTICK-type 8 PA3 V185 diesel
generator set

MAD is short for “Magnetic Anomaly Detector”. Usually deployed as a probe, MAD is towed either behind a helicopter, or aircraft, and based on the fact that any submarine is basically a large mass of steel and other metallic alloys, concentrated in large amounts in an environment otherwise free of such materials. Consequently, the submarines cause fine deviations in the Earth’s magnetic field. These deviations can be detected – and even tracked with the help of a MAD. Although this detection method is meanwhile increasingly problematic – to no small degree also because of an increasing number of shipwrecks on the bottom of most seas (since shipwrecks can cause a similar deviation and the Earth’s magnetic field) – meanwhile very precise maps of such deviations are available, and they can be taken into account. The largest disadvantage of the MAD remains therefore its limited range: the aircraft or helicopter deploying its MAD-sensor has to fly very low and slow over the area where the submarine is suspected, in order to use it effectively.

The differences in water temperature at different depths form the so-called “thermal layers” (or “thermocyclines”), the borders of which also bounce sound beams. In specific parts of some seas and oceans, these differences are so massive, that they enable even large submarines to hide in one thermal layer, or – better said: bellow them – then the thermocyclines are so massive they bounce sounds from any kind of active sonars, or completely block the sounds from reaching the passive sonar.

On the contrary, in the oceans there is a certain layer that is perfectly “transporting” sound waves. This is the so-called “deep sea sound channel” (DSSC). The layer on top of this layer has a too high temperature and bounces back the waves sent within the DSSC. The layer below, has a too high pressure and hence bounces the waves back too. By this way, a wave sent within the DSSC will be bounced back by these layers from one another, this will form a sinusoidal movement of the sound wave and transport it for very long periods over several thousands of miles. This layer is mostly located at depths between 800 and 2.000 meters, but is frequently depending on temperature and pressure. As an example what a DSSC can do: in WWII, some bombers and airplanes used to carry a depth charge that was set to explode within the DSSC and in the USA and UK there were several stations with hydrophones inside this layer. By taking bearings from an explosion of such a depth charge, the position of the crashed aircraft could be determined and a rescue team could be sent out….Today, surface ASW platforms equipped with VDS can lower these into this layer enabling them to detect submarines over immense ranges. Of course, any decent submarine-skipper knows this as well, and will attempt to avoid operating within the DSSC.

The Sound wave is determined by the “gain” strength of the emission and the frequency - which is dependent on the wavelength For frequency a simple rule of thumb can be used: the higher the frequency the less of it will protrude the water (meaning the shorter range), but in turn this is making the frequency easier to concentrate - or “aim the beam” (meaning more accurate position fix). The situation is directly opposite when it comes to low frequencies. All such details and factors fit into the submarine hunting process and procedures: the submarine is most likely to be detected at a long range by low frequency devices, which will provide a blurry – i.e. approximate – position. Once the hunters come closer higher frequencies will be used to track the submarine down and for attack.

that is a lot of data to go through I won't get through it any time soon. Does it actually list any ranges anywhere?

In general, sound is a very uncertain medium, because it has to travel through different other mediums and weather – i.e. water – conditions. Essentially, the detection of underwater sounds depends on four main factors: salinity (amount of salt in water, which varying from one sea to the other), pollution, temperature and pressure (which increases with the depth). These four factors can bend sound waves, bounce them back or even slow them down.

Well I think that the ranges from which the sub are being spotted are quite reasonable, considering that is a fairly advanced ship and an older submarine.