SUBSIM Radio Room Forums - View Single Post - Destroyers Discussion (getting rid of pin point drops)

caspofungin · 11-21-05, 06:57 PM

here's some more info re hydrophones:

"ADM 219/563, Theoretical U/Boat listening ranges. This report was published by the US Navy's 10th Fleet ASW OR Group on 20 Aug 1943. Neglecting reflection and reflection of sound, and considering attenuation only, the distances at which a U-boat could detect the hydrophone effect (HE) for the noise output from a 50-ship convoy, or detect pings from a 40-watt QC projector, are given, in yards, as:

Water noise level-----Hydrophone Effect-----Intercepting pings
High---------------------------7,000----------------------19,000
Medium---------------------21,000-----------------------25,000
Low--------------------------31,000-----------------------27,000

These figures are viewed as reasonable, as U-boat survivor reports claim ranges of 10-15 miles, and in one case 20 miles.
Using sound intensities typical for US submarines, the following distances in yards at which an escort can hear a U-boat travelling at different speeds are calculated using similar assumptions:
Water--------------------Surfaced--------------------Submerged
Noise----------------7kt---14kt---17kt---------------4kt---6kt
High-----------------50---500---600------------------50---750
Medium-----------260---1800---2100--------------260---2500
Low---------------430---2500---2900----------------430---3300

It is assumed that the listening is non-directional and that the ASW vessel is noiseless. It is further assumed that these unrealistic assumptions will probably cancel each other out in practice."

The above is from
http://www.google.com/search?q=cache...n&client=opera

which also has interesting info re number of torps needed to sink a ship, but that's a different discussion.

check the last table, the bold number -- that's surprisingly low range for a sub at (i assume) silent running. is that reflected in sh3?

also QCL, QCE, QGA are American active sonar systems.

11-21-05, 06:57 PM	#36
caspofungin Commander Join Date: Apr 2005 Posts: 459 Downloads: 41 Uploads: 0	here's some more info re hydrophones: "ADM 219/563, Theoretical U/Boat listening ranges. This report was published by the US Navy's 10th Fleet ASW OR Group on 20 Aug 1943. Neglecting reflection and reflection of sound, and considering attenuation only, the distances at which a U-boat could detect the hydrophone effect (HE) for the noise output from a 50-ship convoy, or detect pings from a 40-watt QC projector, are given, in yards, as: Water noise level-----Hydrophone Effect-----Intercepting pings High---------------------------7,000----------------------19,000 Medium---------------------21,000-----------------------25,000 Low--------------------------31,000-----------------------27,000 These figures are viewed as reasonable, as U-boat survivor reports claim ranges of 10-15 miles, and in one case 20 miles. Using sound intensities typical for US submarines, the following distances in yards at which an escort can hear a U-boat travelling at different speeds are calculated using similar assumptions: Water--------------------Surfaced--------------------Submerged Noise----------------7kt---14kt---17kt---------------4kt---6kt High-----------------50---500---600------------------50---750 Medium-----------260---1800---2100--------------260---2500 Low---------------430---2500---2900----------------430---3300 It is assumed that the listening is non-directional and that the ASW vessel is noiseless. It is further assumed that these unrealistic assumptions will probably cancel each other out in practice." The above is from http://www.google.com/search?q=cache...n&client=opera which also has interesting info re number of torps needed to sink a ship, but that's a different discussion. check the last table, the bold number -- that's surprisingly low range for a sub at (i assume) silent running. is that reflected in sh3? also QCL, QCE, QGA are American active sonar systems.