Can subs hover?

[cmdrk]

Source:
http://www.history.navy.mil/library/online/onipubno32.htm

O. N. I. Publication No. 32
[formerly] For Official Use Only [Declassified OP09BH 17 Aug 72]

GERMAN
SUBMARINES
IN
Question and Answer

NAVY DEPARTMENT
OFFICE OF NAVAL INTELLIGENCE,
JUNE, 1918

WASHINGTON
GOVERNMENT PRINTING OFFICE
1918

43. Can submarines remain stopped when submerged, without lying on the bottom?

A very well trimmed boat may do so for about 5 minutes at a time by juggling with her periscope. For longer periods it is only possible in a few localities where layers of different density. occur in the water, e. g., in the Baltic, Cattegat, and Sea of Marmora, where occasionally a boat may lie submerged almost indefinitely1 with all machinery stopped, resting on a layer of salt water.


1 Two German submarines, sent at outbreak of war to watch the southern exits from the sound and Great Belt, succeeded in thus lying submerged, with their motors stopped most of the time, for about 23 hours out of the 24, on 7 consecutive days.

[DanCanovas]

i do this all the time in SH3 :damn:

[cmdrk]

Ah yes, but there has been some lively debates on the subject as well.

I don't feel I'm gaming reality if I stop my sub for short periods - less than 5 minutes. The above vindicates my mode of operation.:p

PS. Did you check the date?

[kylania]

Yes, because it's a game. :)

Though there are optional mods that prevent it.

[Sawdust]

They mention that juggling the periscope can help the sub stay put for a few minutes...how does the periscope come into play? As a sensitive way to displace a little more or less water?

[HunterICX]

I did it once when an convoy came straight in my Path. So I lied down....
I saw the Lead escort closing to 500 meters distance and after that everything happend in slo-motion...my conning tower came up:damn:

[HarLkiN]

i´ve been reading along for a long time, but this is my first post.

sawdust, the answer to your question is the displacement, if the periscope is partially out of the water, and the sub begins to sink, the displacement of the sub under water grows and creates more positive boyancy. so the sub begins to rise, the positive boyancy will change eventually to negative boyancy and the sub will start to sink again. which will start the whole process over again.

in "das boot" buchheim explains it like that and says they called it "to hang the boat up from the scope". not sure of the translation, in german its "das boot am periskop aufhängen"

im sorry for my english, a little out of practice.

harlkin

[Kruger]

Really....does that amonunt of water that the periscope displaces...count so much to the entire weight of the boat ? I find it amazing. It means that also eveybody in the submarine must stay put, because the boat shifts it center of gravity if somebody from the forward torpedo room gos to the toilet.

[HarLkiN]

thats true...

i read that the daily testing dive was to 20 m. they had to calculate the weight of the boat on the surface. buchheim accounts for one time a weight error for the entire boat of 100 liter (~25 gallons) and a trimming error of 30 liters. the petty officer "zentralemaat", was praised by the captain for the high accuracy on the occaison.

so they achieved high accuracy in trimming the boat. the trim had to be adapted to the consumption of fuel, food, the density of the water, etc...

when going submerged, usualy they had to stay on their diving stations and were not to move away if not for important reasons. they had for example buckets in the compartments to follow natures call....

[HunterICX]

:hmm: I suppose that it couldnt be done in bad wheater...

[Sailor Steve]

Really....does that amonunt of water that the periscope displaces...count so much to the entire weight of the boat ? I find it amazing. It means that also eveybody in the submarine must stay put, because the boat shifts it center of gravity if somebody from the forward torpedo room gos to the toilet.
I think it's like using a trim tab on an airplane to offset wind variations. If the boat has proper neutral bouyancy then any change is going to involve pressures amounting to only a few pounds. The periscope could concievably offset that.

On the other hand, it sounds good during a test, but I don't think it would be much of a combat tactic.