Oxygen in U-boat - U-boat Officer's Reply

Stiebler · 08-19-11, 02:49 AM

@Hitman:

When did Lt Paas serve? Good question.
He was a midshipman aboard U-tanker U 461 in 1942 (one full war patrol to mid-Atlantic), then to officer training school, then appointed to a new VIIC U-boat in 1944. He participated in the usual six-month sea-training with the boat, including the tactical exercises against training convoys (and presumably including schnorchel training - I'm not sure about that), then was removed from the U-boat with serious illness. He was still in hospital at the end of the war, in 1945.
Clearly, Lt Paas would have received much experience with the daily details of running an attack U-boat during his intensive training period on his VIIC.

@U-Falke:
I do not know why the devs chose different recharging times for batteries in their different U-boat simulations. Possibly to make game-play more interesting for the casual player?

@Everyone:
Could we please keep this thread on-topic, for the benefit of any future researcher trying to discover authentic eye-witness information about U-boats? That is why I started this thread. Many thanks.

Stiebler.

LGN1 · 08-19-11, 06:20 AM

Thanks a lot for the information, Stiebler!

Do you know how long it took until they surfaced because of the batteries and at what speed they usually travelled submerged? From what I gathered elsewhere battery lifetimes varied a lot depending on age, speed (obviously),...

In addition, I don't think that they surfaced when the batteries were already almost empty. I guess they always wanted to keep some reserves in order to have enough power to escape in case of being attacked.

Regards, LGN1

Stiebler · 08-19-11, 07:38 AM

@LGN1:

I can answer your questions immediately, with information previously obtained from Guenther Paas for a study that I did at his request on the sinking of U 461. (He was not aboard U 461 when it was sunk.) The original information about batteries came from Paas' chief engineer on the VIIC boat.

U-boat batteries could be charged in two ways:
1. Trickle (slow) charge. This was only practical at base, but gave a higher capacity to the battery when fully charged.
2. Fast charge by gearing from the diesel engines. This was used at sea. Fully charged was at lower capapcity (lower amps available) than from the slow charge.

U-boat commanders were always nervous about the state of their batteries, and surfaced to re-charge whenever safe to do so. However, it was not considered 'safe' in sea areas that were regularly patrolled by Allied aircraft, when the boats would surface only at night.

At certain times of the war, and particularly in the Bay of Biscay at two different times in mid 1943, orders were given by BdU explicity to remain submerged at all times, except to surface at night for the minimum time needed to recharge batteries.

As you have said, time for recharge depended on the depletion of their batteries and their state of repair. U-boats would proceed underwater for normal passage at 2 kts (sometimes a little slower, depending on battery capacity), when the batteries would last more than 24 hours. However, no sane commander would wish to exhaust the batteries, so all would try to recharge at least once per day.

Relevant to this topic, U 461 was sunk by air attack on the surface in the Bay of Biscay when its sister tanker U 462 was forced to surface prematurely during their underwater cruise as a result of defective batteries. (At least, that is one story, although it is more probable that both tankers and their U-escort actually surfaced in compliance with current standing orders: at that time to recharge batteries on the surface and to defend against air attacks with combined flak guns. But U 462 had been complaining of defective batteries of 2-3 months.)

Stiebler.

Ligne Maginot · 09-01-13, 12:47 AM

Quote:

Originally Posted by Stiebler

@Everyone:
Could we please keep this thread on-topic, for the benefit of any future researcher trying to discover authentic eye-witness information about U-boats? That is why I started this thread. Many thanks.
Stiebler.

I'm sorry, but it is a categorical imperative to keep it afloat (almost kantian meaning).

Best regards.

JeromeHeretic · 09-01-13, 08:47 AM

Look at this movie:

They talk about high pressure and low pressure system. High pressure was used in big depth, low pressure system was used in small depths, but both systems was suplied from the same high pressure tanks, low pressure was created from high pressure by pressure dividing valve.

Yes, of course this movie is about US submarines, but in german it was principialy done in the same way. Maybe values of used pressure was a bit different.

Sailor Steve · 09-01-13, 08:58 AM

BigWalleye · 09-01-13, 01:23 PM

Steve, I think Ligne Maginot was intentionally necroposting to resurrect this thread. It's a very interesting and useful thread. I never would have searched for it, because I didn't know that such information existed. But I was glad to see it and learn from it. Information like this, especially the first-person recollection, is precious and easily lost. I realize SubSim has to pay for bandwidth, but IMO, this was a worthwhile use. To stand behind my words, I just kicked in another sawbuck.

Ligne Maginot · 09-01-13, 03:10 PM

Maybe Steve in his infinite wisdom already knew this information, but I don't. Nor the new members. If there is a problem, for my next subscription, I will pay double.

Attentively Doctor Frankenstein.

08-19-11, 02:49 AM	#1
Stiebler Fuel Supplier Join Date: Oct 2005 Location: London, UK Posts: 1,237 Downloads: 29 Uploads: 4	@Hitman: When did Lt Paas serve? Good question. He was a midshipman aboard U-tanker U 461 in 1942 (one full war patrol to mid-Atlantic), then to officer training school, then appointed to a new VIIC U-boat in 1944. He participated in the usual six-month sea-training with the boat, including the tactical exercises against training convoys (and presumably including schnorchel training - I'm not sure about that), then was removed from the U-boat with serious illness. He was still in hospital at the end of the war, in 1945. Clearly, Lt Paas would have received much experience with the daily details of running an attack U-boat during his intensive training period on his VIIC. @U-Falke: I do not know why the devs chose different recharging times for batteries in their different U-boat simulations. Possibly to make game-play more interesting for the casual player? @Everyone: Could we please keep this thread on-topic, for the benefit of any future researcher trying to discover authentic eye-witness information about U-boats? That is why I started this thread. Many thanks. Stiebler. __________________ NYGM Tonnage War Mod - More than a mod: it's an experience!

08-19-11, 07:38 AM	#3
Stiebler Fuel Supplier Join Date: Oct 2005 Location: London, UK Posts: 1,237 Downloads: 29 Uploads: 4	@LGN1: I can answer your questions immediately, with information previously obtained from Guenther Paas for a study that I did at his request on the sinking of U 461. (He was not aboard U 461 when it was sunk.) The original information about batteries came from Paas' chief engineer on the VIIC boat. U-boat batteries could be charged in two ways: 1. Trickle (slow) charge. This was only practical at base, but gave a higher capacity to the battery when fully charged. 2. Fast charge by gearing from the diesel engines. This was used at sea. Fully charged was at lower capapcity (lower amps available) than from the slow charge. U-boat commanders were always nervous about the state of their batteries, and surfaced to re-charge whenever safe to do so. However, it was not considered 'safe' in sea areas that were regularly patrolled by Allied aircraft, when the boats would surface only at night. At certain times of the war, and particularly in the Bay of Biscay at two different times in mid 1943, orders were given by BdU explicity to remain submerged at all times, except to surface at night for the minimum time needed to recharge batteries. As you have said, time for recharge depended on the depletion of their batteries and their state of repair. U-boats would proceed underwater for normal passage at 2 kts (sometimes a little slower, depending on battery capacity), when the batteries would last more than 24 hours. However, no sane commander would wish to exhaust the batteries, so all would try to recharge at least once per day. Relevant to this topic, U 461 was sunk by air attack on the surface in the Bay of Biscay when its sister tanker U 462 was forced to surface prematurely during their underwater cruise as a result of defective batteries. (At least, that is one story, although it is more probable that both tankers and their U-escort actually surfaced in compliance with current standing orders: at that time to recharge batteries on the surface and to defend against air attacks with combined flak guns. But U 462 had been complaining of defective batteries of 2-3 months.) Stiebler. __________________ NYGM Tonnage War Mod - More than a mod: it's an experience!

09-01-13, 08:58 AM	#6
Sailor Steve Eternal Patrol Join Date: Nov 2002 Location: High in the mountains of Utah Posts: 50,369 Downloads: 745 Uploads: 249	__________________ “Never do anything you can't take back.” —Rocky Russo

09-01-13, 03:10 PM	#8
Ligne Maginot Gunner Join Date: Dec 2012 Posts: 94 Downloads: 141 Uploads: 0	Maybe Steve in his infinite wisdom already knew this information, but I don't. Nor the new members. If there is a problem, for my next subscription, I will pay double. Attentively Doctor Frankenstein. __________________ NYGM Tonnage War V2.5 – Stand Alone Version NYGM3_New NYGM3_6D Supplement to V16B1 (JSGME) Stiebler4B_Addon_for_V16B1 Hitman Optics NYGM 3.6 (Fixed) Last edited by Ligne Maginot; 09-01-13 at 06:05 PM.

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode

08-19-11, 06:20 AM	#2
LGN1 Ace of the Deep Join Date: Mar 2006 Posts: 1,138 Downloads: 147 Uploads: 12	Thanks a lot for the information, Stiebler! Do you know how long it took until they surfaced because of the batteries and at what speed they usually travelled submerged? From what I gathered elsewhere battery lifetimes varied a lot depending on age, speed (obviously),... In addition, I don't think that they surfaced when the batteries were already almost empty. I guess they always wanted to keep some reserves in order to have enough power to escape in case of being attacked. Regards, LGN1

09-01-13, 08:47 AM	#5
JeromeHeretic Machinist's Mate Join Date: Jun 2011 Location: N 50 4 E 14 25 Posts: 127 Downloads: 266 Uploads: 0	Look at this movie: They talk about high pressure and low pressure system. High pressure was used in big depth, low pressure system was used in small depths, but both systems was suplied from the same high pressure tanks, low pressure was created from high pressure by pressure dividing valve. Yes, of course this movie is about US submarines, but in german it was principialy done in the same way. Maybe values of used pressure was a bit different.

09-01-13, 01:23 PM	#7
BigWalleye Sea Lord Join Date: Jul 2012 Location: On the Eye-lond, mon! Posts: 1,987 Downloads: 465 Uploads: 0	Steve, I think Ligne Maginot was intentionally necroposting to resurrect this thread. It's a very interesting and useful thread. I never would have searched for it, because I didn't know that such information existed. But I was glad to see it and learn from it. Information like this, especially the first-person recollection, is precious and easily lost. I realize SubSim has to pay for bandwidth, but IMO, this was a worthwhile use. To stand behind my words, I just kicked in another sawbuck.