Author Topic: Atlantic Bow modified for underwater refuelling  (Read 10675 times)

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Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #15 on: 14 Apr , 2015, 13:15 »
Here is a updated list of U-boats that we know were modified for underwater refuelling.

U-234
U-244
U-249
U-250
U-310
U-315
U-317
U-481
U-766
U-848
U-858
U-873
U-1023
U-1056
U-1060
U-1165
U-1208
U-1229
U-1233

Offline falo

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Re: Atlantic Bow modified for underwater refuelling
« Reply #16 on: 21 Oct , 2015, 11:39 »
Hi Snowman,

just a question concerning the bow for underwater refueling: How is the piping? From the bow vent to the saddle tank or to the fuel bunker in the lower sections of the pressure hull (fuel oil tank inboard "Treibölbunker 2")?


Thanks in advance and regards
falo
« Last Edit: 21 Oct , 2015, 11:54 by falo »

Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #17 on: 21 Oct , 2015, 12:27 »
I never see any information on this, so I have no idea :(

Tore, should have a better idea of the piping might be, but I imagine the Germans keep it very simple.

Offline tore

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Re: Atlantic Bow modified for underwater refuelling
« Reply #18 on: 22 Oct , 2015, 01:27 »
Simon and Falo.
I agree with Simon. I guess the bow fuelling pipe is very simple like the red line on my sketch below. The refuelleing is done by the original fuelling system having a connection right outside the pressurehull.
Tore

Offline falo

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Re: Atlantic Bow modified for underwater refuelling
« Reply #19 on: 22 Oct , 2015, 02:45 »
Hi Tore, hi Snowman,


thanks for the information, it reads well.


Regards
Falo

Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #20 on: 22 Oct , 2015, 12:37 »
The only other thing I can add to this.

In real life I imagine the pipe run down the starboard side of the boat, as the inlet was starboard and there virtually no room to run piping on the portside between the conning tower casting and the schnorchel.

Tore, one thing I always wonder about, do you think the Germans put a slight down hill angle into the pipe to drain the line or would they not bother about draining the line?

Offline tore

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Re: Atlantic Bow modified for underwater refuelling
« Reply #21 on: 22 Oct , 2015, 13:01 »
Simon.
Indeed I am pretty sure the piping would be run on starboard side. I don`t believe they would have a drain angle on the pipe. The fuelling would had to be done at a pressure against the submerged compensating head to force the compensating water out of the tanks to accomodate the fuel and I guess it might be they could have an airblowing possibility to blow the line. This is quite common on naval fuelling at sea installations.
Tore
« Last Edit: 23 Oct , 2015, 11:52 by tore »

Offline falo

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Re: Atlantic Bow modified for underwater refuelling
« Reply #22 on: 23 Oct , 2015, 11:35 »
Tore and Simon,


find som pictures of boats with underwater refueling bow (IXC and typeseven). Guess you know some of the photos. You have to scroll a little bit down:


http://forum.axishistory.com/viewtopic.php?t=208908


Regards
falo

Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #23 on: 23 Oct , 2015, 12:39 »
Here is a updated list of U-boats that we know were modified for underwater refuelling. Now 30 boats  :)

U-234         TRUE     
U-243         TRUE     
U-244         TRUE     
U-249         TRUE     
U-250         TRUE     
U-310         TRUE     
U-315         TRUE     
U-317         TRUE     
U-481         TRUE     
U-766         TRUE     
U-776         TRUE     
U-806         TRUE     
U-848         TRUE     
U-853         Not see photo evidence
U-858         TRUE     
U-864         TRUE     
U-873         TRUE     
U-875         TRUE     
U-883         TRUE     
U-1023       TRUE     
U-1056       TRUE     
U-1060       TRUE     
U-1165       TRUE     
U-1208       TRUE     
U-1228       Not see photo evidence
U-1229       TRUE     
U-1231       Not see photo evidence
U-1233       TRUE     
U-1234       TRUE     
U-1235       Not see photo evidence

Offline falo

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Re: Atlantic Bow modified for underwater refuelling
« Reply #24 on: 23 Oct , 2015, 14:09 »

Hi Snowman,
thanks for the updated list. Just some "What-if"-thoughts about the late Alberich boats (for example U-1105/"Black Panther" or U-1308) and the refueling bow.

In place of the german navy engineers at the time I would have been a proponent to equip all (late) alberich boats with the rubber coat. Because a boat with this stealth abilities - which only protect them from ASDIC detection by underwater operations - to rig whit a refueling system which works under the surface makes sense.

I have attached two photos of U 1105. One pix is a magnification of the bow (red circle) with a little bit interpolation via Photoshop. IMO the bow does not look like the usual bull nose but the resolution of the picture is not good enough to say with all certainly it is a refueling-bow.

What do you think?

Thanks in advance
falo





Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #25 on: 23 Oct , 2015, 22:31 »
I believe there was no boats with both Alberich and the underwater refuelling system together.
 
The Germans were super keen to update the boats with Alberich and/ or the underwater refuelling system, however, both run into ran into problems during the war. The Oberkommando der Marine must have put a lot of significance into underwater refuelling as Type VIIC's were being modified before the testing was fully finish. The problem was by August 1943 all but one U-boat tanker was lost. So the German gave up the idea underwater refuelling system by mid 1943.

The Oberkommando der Marine planned to use Alberich on the new Type XXI and Type XXII U-boats. But also run to in problems again, as the adhesive was found not to be strong enough to stick the synthetic rubber sheets to the pressure hull and casing of the U-boat. They never really sorted this problem out before the war ended.

Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #26 on: 04 Nov , 2015, 12:01 »

Hi Snowman,
thanks for the updated list. Just some "What-if"-thoughts about the late Alberich boats (for example U-1105/"Black Panther" or U-1308) and the refueling bow.

In place of the german navy engineers at the time I would have been a proponent to equip all (late) alberich boats with the rubber coat. Because a boat with this stealth abilities - which only protect them from ASDIC detection by underwater operations - to rig whit a refueling system which works under the surface makes sense.

I have attached two photos of U 1105. One pix is a magnification of the bow (red circle) with a little bit interpolation via Photoshop. IMO the bow does not look like the usual bull nose but the resolution of the picture is not good enough to say with all certainly it is a refueling-bow.

What do you think?

Thanks in advance
falo



Hi Falo

I can now confirm you are right. There is one Type VIIC's with both Alberich and the underwater refuelling system together. U-1105.

In the higher resolution news reel footage video you found, you are clearly see it. Also I rechecked my photo’s I found three photo’s with more evidence.


Offline OldNoob

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Re: Atlantic Bow modified for underwater refuelling
« Reply #27 on: 04 Nov , 2015, 16:18 »
Silly question here.
How did they filter out seawater contaminates from the fuel? OR Was it that there simply was not enough contamination to be an issue?

Offline NZSnowman

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Re: Atlantic Bow modified for underwater refuelling
« Reply #28 on: 04 Nov , 2015, 16:30 »
Silly question here.
How did they filter out seawater contaminates from the fuel? OR Was it that there simply was not enough contamination to be an issue?

From: The U-boat: The Evolution and Technical History of German Submarines. By Eberhard Rossler. Cassell, 1974 (German), 1981/2001 (English)

"Field trails were hold with UD-4, travelling on the surface at a constant speed; a buoy was released with a towing hawser, hose and telephone cable. The hose was filled with air so that towing hawser and telephone cable floated. The buoy was taken aboard the receiving boat, the towing hawser was made fast and the hose was connected. Both U-boats would then go to periscope depth. After the transfer of fuel the two U-boats would resurface simultaneously, the receiving U-boat let go the buoy and turned directly to port."

This sugguct that there was no seawater contaminate, as the hose was full of air.

Offline tore

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Re: Atlantic Bow modified for underwater refuelling
« Reply #29 on: 05 Nov , 2015, 00:54 »
Sea contamination of fuel.
As all the bunker tanks are seawatercompensated so in essence you could say the fuel was always in contact (or contaminated) by sea water. Due to a substantial difference in the specific gravity between the sea water and dieselfuel, approximately 0.87, the seawater  is settled in the lower part of the tanks, the fuel to the consumption tanks (daytank/settlingtanks) in the engineroom is taken from the upper part of the bunkertanks. If by accident some of the fuel should be seawater contaminated, the engineers would notice this by the spyglasses on the settling tanks which are fitted with drainage facilities to the dirty fuel oiltank below the floorplating. As Simon are quoting, the fuelling hose was filled with air floating both the hose and phonecable. This air would eventually be forced into the bunkertanks where it collects on top of the fuel. As you do not want this air in your system you have venting possibilities inside the submarine. As previously mention I guess the fuelling hose was emptied by blowing same by air which eventually was vented as mention above.
Tore   
« Last Edit: 05 Nov , 2015, 01:27 by tore »