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Originally Posted by Sailor Steve
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Originally Posted by seafarer
I'd imagine that, unless the sea bottom was iron rocks, a big long steel tube would make a pretty stark sonar return relative to a muddy sea floor. Metal objects show up really well in bottom scanning active sonar, in my limited experience with it anyway.
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S-36 grounded on at least three separate occassions...and it worked every time.
http://en.wikipedia.org/wiki/USS_S-38_(SS-143)
http://www.hazegray.org/danfs/submar/ss143.txt
World War II navies didn't have bottom scanning sonar. |
Reading those accounts, I'd still say it was largly luck, or perhaps the surface ships were using only narrow beam sonar and just missed her by not being thorough enough. Not that being on the bottom shielded her from sonar, active sonar at least. WWII sub hunters didn't need anything specific to find a target on the bottom (that is they did not need any special type of sonar like side scan). Their active sonar projected it's pulses in all directions (panoramic sonar) or forward and down (narrow beam). The pulse just keeps going until it's attenuated beyond detection. A very soft bottom will absorb much of the sound energy, but that would also likely be potentially disaster to bottom out on as you may not get free again. The bottom can create interferance that might confound sonar from clearly delineating the sub target, but that's iffy too.
Generally, I still do not see it as being a useful technique to escape an active sonar search.