CjStaal asked:
Yes it is - I've done it several times with no damage whatsoever. The key words are speed (as low as possible, stopped is best), attitude (the boat's, not yours, level is best), and bottom (seabed, not yours). Rocks will almost certainly damage the hull, at any speed and attitude

The first occasion, I succeeded by a combination of luck, circumstances, and judgement. I had just torpedoed two light cruisers in the English Channel in 1940 - pure luck (almost exactly the right place for a speedy intercept) followed by the application of a steely nerve (don't panic!). During a routine sonar check while travelling westbound at around 1900 GMT in the gathering dusk, I heard (my sonarman's lips remained sealed) a terrific roar to the NE - about 8km or so to the NE it turned out. I figured fast warships - a lotta warships, and close!

Surfaced and raced at flank speed to the NW - they must be travelling fast - and had just ordered periscope depth for a sonar check when the leading destroyer was spotted to the ENE, moving fast (25 knots). The first cruiser (a Dido) was soon seen astern of it. Continued at periscope depth, course N, standard speed (The DD's won't hear us at their speed) and gave the Dido a two-fish salvo, slow speed at around 1200m 5 deg. spread, and lined up a second salvo of two, fast speed, 5deg. spread for the second (astern of it, a Fiji), guesstimated to hit at about the same time as the first salvo. Fish were set for 4m depth, magnetic (couldn't guarantee contact angle for contact setting), and all good ol' reliable type ones (early 1940, remember).

All four hit within about 20 seconds (more luck), both ships sank within a minute or two, and we were now surrounded by three smaller and two larger DDs, baying for blood. Depth of the Channel just there is only about 30 metres - the mast tops of both cruisers were still showing, as I saw later. Not the best conditions for evading an attack by one DD, here were five! Headed for the nearest cruiser wreck at 2 knots, silent routine, just above the bottom (both just visible in the observation 'scope by the light of the searchlights on the surface) and slowed to a stop roughly parallel with the wreck, being pinged constantly. If in doubt, try hiding.

Ordered depth 32m at around 1/2 knot, motors stopped, and came to rest on the bottom at 29m, facing roughly west. To cut a long story short, the DDs circled the two wrecks which were very close to one another as the Fiji remained afloat for longer than the Dido, pinging and dropping DC patterns for hours (seemed like days in realtime with no time acceleration). They kept their distance from the wrecks luckily for us, as they must have been able to see the mast tops, and/or they were cautious about collision with the wrecks.

In the early hours, three DDs stopped fairly close together, about 1200m away astern, and the two larger DDs circled in opposite directions. I ordered 25m depth, still stopped. When they were both approaching the stopped DDs (sonar tracked), we moved away at 2 knots, still silent routine, stopped again for the two circling DDs to pass by, and continued to move away slowly, at which time all 5 DDs moved away westward, on their original course, away from us. Wipes sweat from brow, puts brown trousers back in the locker.

I later found out by trial and error what it's possible to get away with if bottoming out, and this showed I was lucky enough to get it spot on the first time. Luck or judgement? I'd say a combination of the two - well I would, wouldn't I?

Use Seabed repair mod, it allows you to bottom out your boat and do repairs (das boot style) but be careful, although you can bottom out as much as you'd like, if you dive to quickly you can hit your bow on the bottom (dont nosedive!)

Just bottomed out several km west of Brest after leaving harbour. NO reported depth as 20m - ordered 18m, descended to 18m, slow ahead, reduced speed to 1 knot, stopped motors and ordered 22m while still moving. Bottomed at 19-20m on depth gauge. Obs. 'scope shows sandy bottom.

I've actually never paid attention to the bottom.
How do you recognize different bottom types? It's always the same sandy color for me?

Kip336 enquired:
Be careful what you ask - you may get an answer very different from what you expected....

I figure that vaguely sandy coloured or grey-sedimenty "fuzzy" seabeds are just that, and are safe. Grey with a definite structure, mottled, slightly "lumpy", very "lumpy", or as round the north of the Orkneys (Scapa to the S), the seabed looks almost paved with large flattish blocks, I avoid. That all says hard and unwelcoming to me.

The observation scope isn't there just for decoration, or drying your newly-washed undies on....

I have found that the slow approach you suggest works for me also. No damage when done timidly enough.

But I have gotten "stuck" on at least two occassions. Had to use flank ahead/emergency back and blow safety to regain control. Has anyone else experienced this?

I think rather that there is only one type of sea bottom and they have no different impacts on your U-Boot's integrity. It is only a different texture.

Fahnenbohn opined:
You may well be right, but in war games (real as well as simulated), discretion is the better part of valour IMHO.

lying DOGGO on the seabottom
 

Yes, in AoD, SHII, and SHV from too shallow crash dives. Generally at dead stop and settling on the bottom caused me no problems. No compressed air or dead batteries were worse. FYI; the expression I'm familiar with for the tactic: "Enemy destroyers again closed the submarine(S-38)https://upload.wikimedia.org/wikiped...28APA-2%29.jpg, and she went "deep", to 80 ft (24 m), and lay 'doggo' as depth charges rained, none close. From 08:04 to 09:30, the S-boat ran silent, using evasive tactics. At 09:30, she grounded on the muddy bottom; she remained there most of the day, destroyers, joined by small boats, continuing to search, without success. At 21:30, the hunted submarine began efforts to clear by backing. During the maneuvering, her port propeller was damaged; but, by 22:01, she was free and underway for the Hundred Islands area on the western side of the gulf. S-38 surfaced to change the air and charge batteries, then dove at dawn, remaining on the bottom all the next day, giving her crew a rest.https://en.wikipedia.org/wiki/USS_S-38_(SS-143) Additionally, I recall a WWII U-boat in the Mediterranean using the same 'doggo' technique but cannot recollect the exact source. Also from Navigation Through the Ages by G.S. Mann (1966)-paragraph 6:salute:: http://articles.adsabs.harvard.edu/c...&filetype=.gif

I'd just started patrolling grid AM32 in the SW corner, when it occurred to me to do a save, continue along the S side of the grid, and mosey on over to the SE of AN13, some 90km NW of Scapa, where I knew the bottom to look like crazy paving. I had in mind a little empirical testing, and reload from the save to continue the mission. At my chosen spot, reduced speed to slow, and ordered periscope depth. Before dropping down to 40 metres to try bottoming, I thought I might as well do a sonar scan. Blow me down if I can't hear two clear contacts, one a probable Small Merchant to the NNE, and a definite C3 to the east.

After checking their direction (my sonar man then piped up with the SM contact) and likely speed, I plotted the approx. course of the SM - due W, slow. The C3 turned out to be heading WSW, more or less in my direction, medium speed, so I intercepted and sank it with gunfire - just 2 AP and 3 HE, amazingly enough. After plotting a course to intercept the SM, I did a sonar check when I guessed we were around 15 km away. I learned long ago that whenever you do a sonar scan, and for whatever reason, do a complete scan. This time I picked up the SM not too far from its guesstimated position, and also another C3 to the SW, coming our way, it turned out

This one took just 2 AP and 4 HE to send it down, and the SM took 7 HE to finish it! Needless to say, I haven't done any bottoming tests, and this excursion is now part of the mission - on the way back to AM32 right now.

Putting your U-Boot on the sea bed is SO easy to do !! I give you my method, but that is so intuitive that I wonder how you have never thought about it !

Method :
- First, determine the depth under your keel.
- Then go "Ahead standard" and dive.
- When depth under keel is 20 meters, go "Ahead one third".
- When depth under keel is 10 meters, go "Ahead slow".
- When depth under keel is 5 meters, stop engines.
- When depth under keel is 1 meter, give order to stay at the current depth.
- And when depth under keel is 0, give again order to stay at the current depth : hydroplanes are set to zero.

That's all ! No need to have a qualified helmsman or a specific mod to do well this maneuver without damaging the hull !

Copied the profile, and used it to go back and do some bottoming tests - result is no difference between apparently "rocky" seabed and other types. As long as you get speed and level attitude right, all will be fine. Fahnenbohn was right.

My impression has always been, though, that without the mod mentioned above that alters ASDIC performance in shallow water, sitting on the bottom will not hide you from escorts. You will just be a sitting duck.

Steve

That's right. In fact, there are, in SH3, no good reason to want to sit on the bottom. Even with Stiebler's patch and its mod called “Shallow-water Asdic” : asdic's efficiency depends only on the sea depth, not on the depth under the submarine's keel.

F.

Fahnenbohn opined:
Read my post at the top of this page - at the time, it seemed the only option, and in those unusual circumstances, it worked. Another time, I bottomed right next to, and parallel with, the wreck of a T3 tanker, with similar results, except the DDs weren't worried about damaging the wreck - several wasserbomben exploded very close, shook the boat, but no damage. The T3 is almost 3x the length of a type VIIb, and the keel-to-deck height is several meters bigger.

In general, of course, and in SH3, you're right.