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Originally Posted by greyrider
rykaird,
if your are in your sound room, with the bearing needle of the hydrophone laying on the target bearing, and your listening to his screws,
on the loudest bearing, look up on the sound operators note pad.
if you do not see "warship", "merchant", or "unknown" written on his notepad, then your target is somewhere between 7.5 km and 34 km.
the sound operator writes the sound cone of the targets screws on his notepad.
but he only writes his soundcone for ranges 7.5 km and less, beyond that its up to you to determine range by sound cone and amplitude.
the sound operator must be recording the inner sound cone, because the complete sound cone can be as much as twenty degree's, even at 8 km.
anything over 7.5 km, he writes nothing.
anything 7.5 km and closer, he begins to draw and record his soundcone of the target by writting it on the notepad.
he does this by writing the type of sound contact he has on his notepad on every bearing he hears the inner cone, which is the width of the soundcone,
which is determined by range.
example:
merchant bearing zero degree's, range 8 km, target is closing, target course is 180, speed unknown, u-boat at dead stop, course 000.
target range now 8 km, sound operators notepad blank
target range now 7.5 km SO notepad entry, "merchant" appears on bearing ooo: fringe bearings 359 and 001 blank, sound cone width is 1 degree.
target range now 7 km SO notepad entry, "merchant" appears on bearings 359 and 001: fringe bearings 358 and 002 blank, sound cone width is two degrees.
target range now 6.3 km SO notepad entry, "merchant" appears on bearings 358,359 and 001,002: fringe bearings 357 and 003 blank, sound cone width is four degrees.
target range now 4.1 km SO notepad entry, "merchant" appears on bearings 357,358,359 and 001,002,003: fringe bearings 356 and 004 blank, sound cone width is six degrees.
target range now 2.8 km SO notepad entry, "merchant" appears on bearings 356,357,358,359 and 001,002,003,004: fringe bearings 355 and 005 blank, sound cone width is eight degrees.
target range now 1.0 km SO notepad entry, "merchant" appears on bearings 355,356,357,358,359 and 001,002,003,004,005: fringe bearings 354 and 006 blank, sound cone width is ten degrees.
target range now 400 m SO notepad entry, "merchant" appears on bearings 354,355,356,357,358,359 and 001,002,003,004,005,006: fringe bearings 353 and 007 blank, sound cone width is 12 degrees.
for longer ranges i compare the amplitdue of the screws verse the background noise of the hydrophones, if it seems that the noise is louder than the screws, then i know the target is
at least over 15 km away.
if the screws sound louder than the background noise, then the target is closer than 15 km.
hope this helps, and good luck!
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