[PappyCain]

The speed of a wave is the rate at which vibrations propagate through the medium. Wavelength and frequency are related by:

l = c/f

where lambda = wavelength, c = speed of sound in the medium, and f = frequency. The speed of sound in water is approximately 1500 m/s while the speed of sound in air is approximately 340 m/s. Therefore, a 20 Hz sound in the water is 75 m long whereas a 20 Hz sound in air is 17 m long.

Or to put it simply, sound travels faster and is louder underwater and acoustic equipment can pick up u/w sound to include music, tapping, whirring, conversation, etc. Sound propagates well thru steel into the water column. As stated above, going silent meant shutting all down, using ballast tanks - but pumps had to be maintained. Eventually war ships pinged or sent out a sound wave that would bounce off an object and the direction, speed, location of a sub would be instantly calculated even if the sub went silent. The limits of a ping T/D (in WWII) are unknown to me but if a sub was beyond the ping propogation I imagine silent running was the best option. When you hear a sonar ping increasing rapidly the ship is getting a return signal bouncing off your sub and he is closing on you (obviously) and once detected you have a problem. Running silent will not help. When the drums are dropped better go flank to port or starboard 10 degrees. But then when they shot the charges out a distance to the sides it was hard to use that as a counter measure. I have pointed my bow to the oncoming vessel above and was able to go flank speed deep and away from his stern when he was above me and get distance. But not always. When they double team you it is all over. You have an appointment with the grim reaper. Other subs in a wolfpack might help by pulling their attention away.

S' PC