Grounding Boat on the Bottom - Question

[ChrisG2100]

Can you ground you boat in the bottom and have the destoyers not "see" you. This doesn't work in SH3 because the destroyers sonar isn't modeled to lose the sub in the bottom clutter?

Thanks

[donut]

& NO,if you are within depth range of DDs sonar.Prehaps under thermal @ max dive. Bottom clutter dosen't figure.

[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.

[ChrisG2100]

U-Boat captains used it in desparation. It was better then making a hole in the water. Just Hoped ubi would model it.

Thanks

[Sailor Steve]

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.

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.

[seafarer]

Originally Posted by Sailor Steve

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.

[ChrisG2100]

Just as a note. There isn't much to do when being depth charged. Bottoming out would be nice. I got the idea from Eric Topps book. He used it at least once.

[manucapo]

my experience is that once they already detected you
is better to zig zag at slow speed than to ground
cause it seems that once they detected you and you ground, they just keep
depthcarging your general area (they dont seem to know exactly where you are)

but they will just keep depth charging and you might get lucky,

tho this has never been succesfull for me

[Gunfighter]

There's an old sub saying "Run Silent Run Deep" If I know I've been detected I Dive to 250-300ft and rig for silent running and zig zag away It's worked for me I have never Grounded because of hull damage.

[Sailor Steve]

Originally Posted by manucapo

my experience is that once they already detected you
is better to zig zag at slow speed than to ground
cause it seems that once they detected you and you ground, they just keep
depthcarging your general area (they dont seem to know exactly where you are)

but they will just keep depth charging and you might get lucky,

tho this has never been succesfull for me

The sand on the bottom absorbs a large amount of the force, so grounding actually worked quite well (at least for the subs which survived to tell the story ).

Originally Posted by seafarer

Their active sonar projected it's pulses in all directions (panoramic sonar) or forward and down (narrow beam).

This picture shows the different beams used during the war. I don't know how effective grounding should be, just that some captains said they used it to good effect when trapped in shallow water. Again, some may have tried it and failed, but we can't ask them.

[-Pv-]

If you're looking for a sure way to get away every time, in this game, grounding is not it especially in shallow water.
-Pv-

[odjig292]

When the Allied convoy escorts started to be active in 1944 in the English Channel to clear the way for the D-Day invasion, they wasted a lot of depth charges on sunken wrecks that gave sonar signals like U-boats. The Admiralty came out with a map of known wrecks to reduce the time being wasted on them. It would seem a subamrine sitting on the bottom would be picked up just as easily as the wrecks.

[ReallyDedPoet]

Originally Posted by Sailor Steve

Nice pic SS


RDP

[Sailor Steve]

Originally Posted by reallydedpoet

Nice pic SS

Thanks, but it's not mine. I originally got it from page 12 of this ancient thread:
http://www.subsim.com/radioroom/show...ighlight=drops