Torpedo Stowage

[rudewarrior]

In my research I just found a document that said in the type VIIC that:

1. G7a can be stored in all places except auxiliary stowage [the two extra stowage slots in the fore], because there the engine chamber would be positioned at the support point.
2. G7e can not be stored in both deck containers and in aft reserve stowage because access for maintenance is insufficient.

I knew about the deck containers, but not the aft stowage.

Did this go for all Type VII's?
Did this ever change during the war?

Edit: It did change during the war. In March of 1943 a standard load out was issued that called for 2 TIII Fat II's in the aft of type VIIb, c, and d u-boats. Three other sets of load outs were issued at various times that each called for 2 TV Zaukönig's in the aft. So they were certainly allowing eto's in the aft reserve by then. I figure one of three things happened. Either they figured out early in the war it was impractical and just forced the crews to maintain the torpedoes, their maintenance capability became more sophisticated allowing them to service eto's in the aft compartment (I find this unlikely), or the TIII was easier to maintain than the TII and it changed then. The last possibility seems the most likely, but I can't really find any indication that the TIII is anything other than a retrofitted TII with a functioning depth keeping mechanism. Anyway, hopefully someone might have an answer to this. Maybe next time I will check the sources of my own mod before I post.

Were there any conditions like this for the Type IX's?

Please include a source if possible.

Thanx in advance.

[Mittelwaechter]

Afair - they were able to heat the electrics in the tubes - all forward and backward VII/IX. In a VII the 2 eels internal reserve stored on the floor forward and the two outmost eels of the four torpedos under the floor plates forward could be heated and maintained (i.e. charged).
The two torpedos stored under the floor plates, directly under the two internal reserve had to be steamers, because they were unaccessable as long as the two above were not removed (into the tubes).
The torpedos were heated in pairs - in a VII 4 heaters for 8 torpedos forward. All were constantly heated as it took some time to get them to temperature.
The backward internal reserve was under the floor but accessable and the tube and the reserve made a pair to be heated (afair!)
You mentioned the backward internal was not accessable/insufficiently accessable? Where did you get that information?

A type VII had to load at least four steamers - two internal forward and two in the deck containers. All other torpedos could be electrics in all variants.

I don't know much about type IX, but they had probably similar problems/conditions.

The ordered standard loadout was more than often subject to the availability of torpedos at the base.
An electric was way cheaper than a steamer and they prefered to use the steamers for surface units (fast/bubbles no problem, as the attacker was visible anyway).

The general storage layout of a VII didn't change over the war, but with the allied air superiority they didn't use the deck containers any longer. A late VII may have carried only 12 torpedos - dependent on the area of operation.

I donated all my sources in the 90's to the local library, but maybe you've got some inspiration for further research.

[Aktungbby]

http://www.shipwreck.net/pdf/OME_Papers_35.pdf Some useful diagrams showing the storage below decks The pics may be distressing for Kaleuns though

[LGN1]

Hi Mittelwaechter,

the original VIIC manual (http://www.uboatarchive.net/Manual/Manual.htm) states at page 50:

"G7a can be stored in all places except auxiliary stowage, because there the engine chamber would be positioned at the support point.

G7e can not be stored in both deck containers and in aft reserve stowage because access for maintenance is insufficient."

Regards, LGN1

[Mittelwaechter]

Well let's think about it. There was a support device in the forward torpedo room to hold two internal reserve torpedos on the floor level.
This device was in such a bad position, it made it impossible to store steamers on it?
Would they have relocated the device? There may have been some weird U-Boot design reasons to hinder a reconstruction, a relocation of this support device.
Would they have installed an adapter, something to divide the support point into two seperate support surfaces, sparing the desired area to enable access as necessary? (And what maintenance was necessary with a G7a possible in the tubes but not possible outside?)
This position is the overall best storage area in the U-Boot concerning access - safe on the floor, not under plates, not in the tubes. And here they managed to cause such a problem?

In the aft compartment they were able to remove a G7e torpedo from the tube to maintain it, but couldn't lift the internal reserve from under the floor to do it?
How did they ever manage to load the reserve?

I know the Germans were funny enough to document misinformation, just in case the papers went into the wrong hands. Not sure, if this is the case here.
Someone mixed aft and forward, Eto and Ato, above and under the floor plates in this documentation. Maybe per design, maybe a mistake in translation.
In the forward compartment, the underfloor reserve was limited to two steamers in both center positions, because this area was not accessable while fully armed.
This makes sense to me (as the information concerning the deck containers).

Any person responsible for torpedo stowage would have known what to put where, they wouldn't have had to check this documentation.
As you stated yourself, the situation 'suddenly changed' in 1943, because you found some documentation of two Etos in the aft compartment.


Greetings.

[Mittelwaechter]

Addendum: a major part for the armament section of your online document is the loadout configuration for a torpedo/mines mixture.

If they filled the aft tube(s) with mines, they may have left any heating and recharging equipment for the aft compartment at home. Here they would have been limited to an internal steamer reserve aft.

[LGN1]

Hi Mittelwaechter,

I have no idea why they didn't move/change the support point. Maybe it couldn't be done that easily? Or it was not a real limitations because u-boats anyway carried G7e in the stowage and not only G7a? I think it's a moot point to discuss this. We will not figure it out. From the document I conclude that (at least in 1940) it was not possible for whatever reason.

Concerning the aft compartment: Maybe they could do the maintenance, but it was too difficult/cumbersome and thus, the disadvantage of having a G7a was small compared to the maintenance difficulties.

The original German version states the same, i.e., there is no translation error.

I find it hard to believe that it's an intended misinformation. The document contains tons of reliable information which I would judge much more critical than the G7a vs. G7e torpedo stowage layout. Why should they fake this information and not the other parts?

Anyway, everybody can believe whatever he wants. But, I myself consider the document to be the best source for how torpedos were stored in the VIIC (at least in 1940).

Best, LGN1

PS: From what source do you have the information "the underfloor reserve was limited to two steamers in both center positions"?

[Mittelwaechter]

Hi LGN1,

we don't know how much of this document are facts or misinformation. There may be more variants of it with slightly different data. It's a possible way to find a leak/spy and to track the journey of a document.
The document was not necessary for daily use aboard and could read any information. Imagine a 'manual' for your NASCAR racer, stored in the glove compartment - stolen by a competitor.

I believe to remember - read in a book, report or online - they couldn't heat, charge and maintain both inner forward reserve torpedos located under the two stored on the floor. This would limit the space to Atos.
However, I have no positive reference to state it as a fact.

Regards

[Mittelwaechter]

They stored G7e aft internal!

KTB Schepke - U-100 - Type VIIb - 2nd War Patrol - Sept. 40
http://www.uboatarchive.net/KTB100-2.htm

Page 11 - 23.15 "Firing tube V G7e relative bearing to target 080°, target speed 8 knots, depth 3 meters, distance 54 seconds."
Page 13 - 0050 "Torpedo fired from tube V, G7e. Relative bearing to target 80°, target speed 8 knots, depth 2 meters, distance 53 seconds."


KTB Metzler - U-69 - 1st Type VIIc - 3rd War Patrol - May to July 41
http://www.uboatarchive.net/KTB69-3.htm

Page 7 - 09.49 "To avoid surprises, gave the steamer a stern shot: Bow left, target angle 90°, depth 2 meters, Eto tube runner ejected with mine gear - Crash dive. Running time 127 seconds - 1900 meters. Hit center." (Eto = Electric torpedo)
Page 8 - 00.36 "Coup de grâce: Stern shot Eto depth 3 meters. Again a tube runner - ejected with the mine gear - running time 30 seconds = 625 meters. Hit center: Steamer sinks immediately."

TypeVIIb and Type VIIc - 1940/1941 - both have performed two stern shots with G7e/Eto

[Aquelarrefox]

hey in external store they could carry fat or lut gas torpedos, or sonly g7aI

[Mittelwaechter]

The FAT and LUT systems were mechanic devices (interconnected rotable disks) to be set from outside the tubes via a special retractable gear (a spindle through the tube wall into the torpedo). There was no maintenance necessary. The external reserves were stored dry, so it shouldn't have been a problem to store a G7a FAT or LUT in the deck containers.

I don't know if they did it.

[LGN1]

Originally Posted by Mittelwaechter

They stored G7e aft internal!

KTB Schepke - U-100 - Type VIIb - 2nd War Patrol - Sept. 40
http://www.uboatarchive.net/KTB100-2.htm

Page 11 - 23.15 "Firing tube V G7e relative bearing to target 080°, target speed 8 knots, depth 3 meters, distance 54 seconds."
Page 13 - 0050 "Torpedo fired from tube V, G7e. Relative bearing to target 80°, target speed 8 knots, depth 2 meters, distance 53 seconds."


KTB Metzler - U-69 - 1st Type VIIc - 3rd War Patrol - May to July 41
http://www.uboatarchive.net/KTB69-3.htm

Page 7 - 09.49 "To avoid surprises, gave the steamer a stern shot: Bow left, target angle 90°, depth 2 meters, Eto tube runner ejected with mine gear - Crash dive. Running time 127 seconds - 1900 meters. Hit center." (Eto = Electric torpedo)
Page 8 - 00.36 "Coup de grâce: Stern shot Eto depth 3 meters. Again a tube runner - ejected with the mine gear - running time 30 seconds = 625 meters. Hit center: Steamer sinks immediately."

TypeVIIb and Type VIIc - 1940/1941 - both have performed two stern shots with G7e/Eto

The KTB must be falsified to confuse the enemy

Just kidding, Mittelwaechter! Great find and thanks for sharing!

My guess still is that probably it was considered unpractical in the beginning, but later it turned out to be practical (unpractical according to peace-time regulations, but in war-time possible).

Regards, LGN1

PS: Just a side note: KTBs were in fact sometimes falsified to hide mistakes, e.g., Lemp was ordered to erase all entries concerning the sinking of Athenia from his KTB, see the book "U-Boat Attack Logs" by D. Morgan & B. Taylor.

[Mittelwaechter]

I fully agree to stay alert and doubtful in matters of military/official information made public. We read, watch and hear what we shall read, watch and hear.

Truth in general is a matter of interpretation - and often a matter of secrecy.

[rudewarrior]

Originally Posted by Mittelwaechter

The external reserves were stored dry, so it shouldn't have been a problem to store a G7a FAT or LUT in the deck containers.

I don't know if they did it.

Per the KTB's that I mentioned in the original post, later in the war they listed TI FaT I's in external storage. Granted it was only for Type IXd's, since by then (with the exception of IXd's and IXc's heading to southern waters) they had stopped storing externals (BTW: this was because depth charges were causing the compartments to flood severely changing the buoyancy and trim of the boat, not allied air power per se). IXd's would imply Type IXc's could as well, and I assume Type VII's as well, since the storage compartments seemed to function the same way between the two types. Same implications for the LuT torpedoes.

Originally Posted by LGN1

My guess still is that probably it was considered unpractical in the beginning, but later it turned out to be practical (unpractical according to peace-time regulations, but in war-time possible).

This is kind of aligned with my theory: In combat, you do what you need to kill enemy and survive. If that means you have to put a G7a in place where a bad support point is, you do it. If that means you have to store a G7e in the rear compartment, you do it. And doubly so if the Kaleun says so. So I think this falls under that "practicality" umbrella.

This is based in part on my non-combat service in the 1990's US Army. There were plenty of times I can remember being told to do something that didn't make any sense or wasn't in some manual somewhere that way. I often got to told to do this by a sergeant, and the choices were to do it or do it after I did some push-ups. I chose to avoid the push-ups.

[Mittelwaechter]

Followup:

I stumbled over Topp's KTB - http://www.uboatarchive.net/KTB552-6.htm

Page 1 - 23/24.10.1941

He loaded 2 Atos and 12 Etos into his 552 VII C - and consequently the Atos were to be stored in the deck containers. So 12 Etos were stored inside the pressure hull, in all available tubes and reserve positions - aft as forward - above and under the floor plates.

Every reserve torpedo storage space was accessable for charging/venting Etos as for greasing the drive shaft and refilling compressed air for the gyros and the depth keeping device.

Maybe they had to lift/shift the torpedos around to service the eels stored under the floor plates (+ center forward). But they definitively stored Etos there too.