Quote:
Originally Posted by Pacific_Ace
Im wondering about the effectiveness of ww2 passive sonar vs the speed of the destroyer using it. Currently Im replaying a situation I saved that placed me almost dead ahead of a TF containing 8 AS ships, 3 to a side, one ea front and back, the QE and the Hood  .
Im inside the screens line of travel waiting for my juicy targets and Im at 1 kt and they are traveling at 19 kts. At this point Im tracking by sonar, yet they still detect me somehow and go active. Im just having a really hard time believing British sonar in late 39 is this good. Any idea whats going on here? |
The effectiveness of any sonar system, surface ship or submarine, is inversely proportional to the speed of the platform using it. In other words, the faster you go, the worse your passive (listening) sonar gets. There are two main reasons behind this.
As you increase in speed, water flow over the sonar array increases, producing ambient noise. Think of driving in your car, listening to the radio with the window down. If you are at 5 mph the wind noise generated by the car moving is very slight and you can hear the radio with ease. As you increase in speed the wind noise also increases and you are forced to continuously increase the volume of the radio in order to hear it clearly. A similar principle applies to sonar. However, with sonar, at a certain point own ship's speed can render passive sonar completely ineffective (this point varies with the system) and you won't be able to hear a freight train coming at you, much less a quiet submarine.
The other factor is own ship generated noise. As you increase speed, your propulsion plant increases its noise output. The engines, fuel pumps, lube oil pumps, coolant pumps, bearings, reduction gears, and propellers all get noisier as you go faster. This increased noise output from your own ship will make your passive sonar much less effective.
Active (pinging) sonar is much less effected by speed and thus is the type most often used by surface ships while conducting generalized searches. Submarines, however, contrary to what is shown in the movies rarely use active sonar because the ping put into the water will easily reveal it presence to the enemy and allow them to locate you.
I do not have the figures for WWII British sonar systems, but an educated guess would be that at 19 knots a destroyer's passive sonar system would be borderline effective at best. If this is what is happening in the game, it would be my opinion that the destroyer's sonar is modeled incorrectly.