Tores mailbox VIIC and VIIC/41 operation and technical details

[maillemaker]

In 'Das Boot' during the Alarm they the crew is shown running forward and swatting a hanging light/shade out of the way.  I was amazed that it could tolerate that without blowing the bulb or damaging the cable.

Realistic?

Steve

[tore]

Steve.
Battlestations or divingstations as we called it, would generally imply mostly people moving from forward compartment to aft. This would mean the officer on watch would give the order to the trim man prior to the divingstation order:" pump 400 liters from aft to fore". When you heard that order you would  anticipate the next order:" divingstation". In the CPTOs mess and the wardroom you usually could hear pretty much of the orders given in the controlroom and the lamps in the CPTO,and PTO messes were usually moved to the side, in the wardroom the passageway was on the stb side leaving the lamp hanging over the table undisturbed. When the order was given, contrary to the Movie, the rush of people was not as noisy and dramatic. But of course the movie people wanted to have some drama.
Tore

[maillemaker]

Battlestations or divingstations as we called it, would generally imply mostly people moving from forward compartment to aft.

Hi Tore,

I assume you mean people moving from aft compartment to forward?

Steve

[Don Prince]

Hello Mr. Tore,


I'm having an issue about (rethinking) how to describe the ballast tanks...


In the type VII U-Boat the forward, center, and aft tanks are described as Tauchzelle or diving cells, and the saddle tanks are described as Tauchbunkers or diving bunkers.


Diving cells are strictly water ballast tanks, and diving bunkers are configurable to a reserve fuel oil (RFO) or a water ballast.


When did these tanks become Main Ballast Tanks and labeled MBT 1, MBT 2, MBT 3, MBT 4, and MBT 5? Was this done in translation to eliminate the confusion between the Gerrman diving cells and diving bunkers?


Which is correct?


Regards,
Don_

[tore]

Steve.
The largest accommodation for the crew was the fore torpedoroom having 12 fixed bunks as well as hammocks,  the majority of these people had their divingstations aft of the accommodation. The officers and CPTOs had their divingstations aft of their accommodations as well and even most of the PTOs, engineers and electricians had to move aft , to the engineroom and E room, hence the the trim of the boat had to be compensated by a larger trimming moment pumping 400 liters from aft to fwd. trimtank.
Tore

[tore]

Don
I Guess the RN English nomination derives from the translation done by the RN when they got hold of the VIIC documents during WW2. I am pretty sure the Germans used the expressions mentioned on the original GA drawings. The problem could be that the various tanks were used to a certain extent differently by the German Navy and RN. F. inst the Untertriebzelle in RN English we used the nomination Q tank for quick diving whenever you had to change depth quickly (e.g. not dynamically) as f. inst. in the case you had to avoid ramming. The German used the Untertriebzelle to assist a quick diving from the surface ( to overcome the "surface resistance") and got the name for that purpose, Unter ( under) trieb (force) zelle. The Germans did the numbering for frames, tanks, dieselengine cylinders etc starting from aft we did the opposite. The Germans were not consistant though, as the fore torpedotubes have the nos 1 & 3, 2 & 4 and the aft no 5. It is hard to state what`s correct I Guess describing a german piece of engineering would be using the German system, for a non german speaking english person it might give a better understanding using the RN English. But I really have no idea.
Tore

[Don Prince]

Hello Mr. Tore,


During a submerged torpedo attack, how many people would be in the tower?


I count three (3)
- the captain
- the helmsman
- and someone to input the TDC data?


Or was that a 2nd job for the helmsman?


Regards,
Don_


P.S. I have until December 1, 2016, to make any changes to Skizzenbuch according to my managing editor.  I should be finished in about two weeks with the clean-up and changes and will upload it to dropbox.  I believe I should use FBT 2 and 4 instead of MBT 2 and 4 because of the different German wording - Tauchbunker Vs Tauchzellen.  The US and British reports on different U-Boats use the FTB term for the RFO or Ballast Tanks...


If you have any suggestions, then please let me know???


Regards,
Don_

[tore]

Don.
I assume you are referring to submerged launching of torpedoes at periscope depth. We usually had two men in the tower and kept the helmsman in the controlroom. However our CO preferred to carry out most attacks (simulated) from the controlroom as can be seen from the image below.
I guess it is a good idea to change the saddleballasttanks to FBT instead of MBT.
Tore

[Don Prince]

Hello Mr. Tore,


If it were a submerged torpedo attack and the CO was using the attach periscope in the tower, then there would be another person involved in the operation; a helmsman, the CO, and who would the person be handling the TDC? Who would normally input the info into the TDC on any type of torpedo attach scenario? I thought the No. 1 Officer handled a torpedo attach from the bridge using the UZO... Could they all fit into the cramped tower space, or would the helmsman need to take his station back in the control room?


Regards,
Don_

[tore]

Don.
I don`t remember 100%, but I Guess the helmsman would be in the controlroom. We very seldom had the helmsan in the tower. He was generally either on the bridge during surface harbourmaneuvre or in the control room.
Tore

[NZSnowman]

Tore, can you remember how the wooden deck hatches were fixed to the deck so they would not float away?

[tore]

Simon.
All the wooden hatches had hinges and were locked in place, a typical example is the hatch adjacent to the hydraulic cylinder of the schnorchelmast seen on the images below.( U 968). For the wooden deckhatches connected to the pressurehull hatches was a special arrangement whereby you opened the wooden deckhatch simultaneously with the pressurehull hatch by a system of hingerods as can be seen on the image. Note the wooden deckplanks were bolted to the steel supports shown on the image. 

[NZSnowman]

Simon.
All the wooden hatches had hinges and were locked in place, a typical example is the hatch adjacent to the hydraulic cylinder of the schnorchelmast seen on the images below.( U 968). For the wooden deckhatches connected to the pressurehull hatches was a special arrangement whereby you opened the wooden deckhatch simultaneously with the pressurehull hatch by a system of hingerods as can be seen on the image. Note the wooden deckplanks were bolted to the steel supports shown on the image.

This images has been resized. Click to view original image.


This images has been resized. Click to view original image.

[tore]

Simon.
I can`t remember the exact details, but below is an image of KNM Kaura 1953 showing some details of the wooden casingdeck hatches may be i can be of some help.
Tore

[SnakeDoc]

Hi Don,

If it were a submerged torpedo attack and the CO was using the attach periscope in the tower, then there would be another person involved in the operation; a helmsman, the CO, and who would the person be handling the TDC? Who would normally input the info into the TDC on any type of torpedo attach scenario? I thought the No. 1 Officer handled a torpedo attach from the bridge using the UZO... Could they all fit into the cramped tower space, or would the helmsman need to take his station back in the control room?

During submerged attack, the TDC was operated by (Ober)Bootsmann, CO was at the attack periscope. There was space for three men in the conning tower. Between helmsman saddle and attack periscope was hatch to the control room and ladder to the bridge. The TDC operator was on the most inconvinient position.


As you said, IWO was at the UZO sight column duiring surface attack and in the control room when submerged.


--
Regard
Maciek