Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Hello Mr. Tore,

What if U-995 was submerged and a depth charge attack resulted in the support A frame on the port side was completely broken and there is no support for the port drive shaft and propeller. And to make it more interesting, the starboard diesel engine has a damaged #1 cylinder liner and piston and you have no spares...

When you finally surface; you can't just row the U-Boat back to your home port.

1. You could pull the piston drive arm, disable the injection pump and run on the other 5 Cylinders, but the engine would be terribly out of balance.

2. Would you pull the piston rods for all cylinders in the block with the damaged piston and liner, and run on the other 3 cylinders which would be balanced on the crank shaft?

Regards,
Don_

[tore]

Don. May be the ultimate solution would be to rise the periscope, collect the bed clothes and make a sail. I am not sure  if the crew would sacrifice their bedclothes though. In that case I would try to run on 5 cylinders, charging the batteries and use the E-motors limping home. I don`t see the point in dismantling the other moving parts in the engines. When the propeller shaft is damaged go back to the ultimate solution.

Tore

[SG]

 

[Don Prince]

Hello Mr. Tore,

Perhaps they could use the port diesel to charge the batteries and run on the starboard e-motor. I believe that would be making the best of the situation with these conditions.

What do you think?

I'll need to search and see if I can find out how U-45 (in the photograph) made it back with the damaged port side...

Regards,
Don_

[tore]

Don, as long as you don`t use your image as a reference for the situation, yes.  Your image shows a damage which might involve a flooding of the E-room, with main motors and switchboard making same useless. Further a major intrusion of water in an end- compartment and MBT 1, approximately a total of  62m3 if filled and a trim moment of - 200.3 meter tonnes would create a dangerous situation which might require a compensation, which again might lead to a larger aft draft.
Tore

[Don Prince]

Hello Mr. Tore,

The documentation only states U-46 (not U-45) was attacked with a/s bombs, one of which was a direct hit on the stern, blowing a large hole in the outer plates. One crewman killed. U-46 returner to Kiel 29.10 40.

It looks like about 3 months later, back into action...

12.2.41 Left for the North Atlantis, to operate between the Shetlands and the Faros. U-46 returned to base 4.3.41.

It looks like the starboard side was OK to get back to Kiel for repairs...

Regards,
Don_

[Raymic1]

Hello Mr Tore
I hope you are keeping well.
Apologies if you have discussed this before but having served both on Type VIIc and a Type VIIc\41 you are in a unique position to answer my question.
As not many interior detailed pictures exist of Type VII/c we only have  U995 Type VIIc/41 Kaura to show us detailed interiors.


It is written that the /41 had a stronger hull had the same Engines but was made lighter by less heavy internal equipment to compensate.


Although U995 Kaura had slight Norwegian modifications (and all the present day colors are incorrect) can you advise what  major internal equipment was different on U995 from a Type VII/c.


Both the subs you served on were middle to late war. U926 and U995


For example a major internal change on the Type VIIc was the Electrical Switchboard going from a an Early war Round Type U552 to a Rectangular Type as seen in U995.


Thank you. Stay safe.

[tore]

Raymic1

Thank you for the good wishes, going on 92 takes its toll but I guess I should`t complain. Making a survey of all the modifications and years on the VIICs

would probably be a task for a historian rather than an engineer, in fact the development of the VII class has been a continious process from the very beginning. However

if we concentrate on the step from the first ordinary VIIC to the VIIC/41 you are right, the increased max. crush depth was the main thing. This was achieved by increasing the steelplate thickness particulary in the tower and controlroom area. This of course influenced the deplacement which implied a reduction of weigth. The weight reduction was obtained by doing a lot of modifications in the engineroom. By making the diesels nonreversible the heavy reversing mechanism was removed, the most visible item is the vertical reversingcylinder on top of the engine, up front. Then likewise the lubeoil purification plant. By introducing the non reversible dieselengine the surface maneuvring had to be substituted by a simpler main switch board. The switch board on all our VIICs ( ex U 995, U-926 and ex. U 1202 were all alike as all the main engines were the same. The U-995 had quite significant flare, ( Atlantic bow), the other less.  Contrary to many images the U 995, U 926 and U 1202 had a ringfloat air valve on top of the snorkel mast, not the hinged type as on the museum U 995 today. As you might see there are a lot of minor differences within the VIIC class, some time you have the feeling that several yards made, within limits, their own design, particularly in the latter part of  WW2.   U 995 never operated with snorkel in WW2, in fact she was at the yard installing the snorkel at the surrender.
Feel free to ask further questions.
Tore

[Don Prince]

FYI....
Don_

Skizzenbuck Page 106

"U-Boat Type VII C/41 Pressure Hull Construction

The Type VII C design was subjected to a weight loss program by using lighter machinery wherever possible, and lighter electrical components (i.e., the e-motor rotary switchboard control panel replaced the heavier toggle switchboard control panel). The results were a weight reduction of 11.5 tons which meant they could increase the thickness of the pressure hull in the Type VII C by 10 tons. For example; the control room hull thickness was increased from 18.5 mm to 22 mm. The test diving depth (60% of the crush diving depth) increased from 150 m to 180 m, and the destruction diving depth increased from 250 m to 300 m. This altered Type VII C construction plan was designated the Type VII C/41 because it was approved in 1941 (this was only a modification of the Type VII C and did not introduce delays in the intermediate size U-Boat building program for the contracted manufacturers). The major reason for this plan was to allow the Type VII C/41 U-Boat to avoid ASDIC/SONAR detection by diving so deep as to weaken the return ping reception to look as background noise."

In Addition:
1. Degaussing cabling longitudinally around the pressure hull and casing was removed in the late 30's to early 40's
2. The two (2) external torpedo storage tubes were no longer utilized under the deck (reduced from 14 to 12 torpedoes)
3. The 88mm cannon was removed and the need for the shell storage
4. The ASDIC/SONAR - S-Gerat equipment development was dropped (reason for the longer Control Room in VII B to VII C). This
    space was later used for RADAR equipment.

Regards,
Don_

[Raymic1]

Don and Tore
Thank you for this fantastic information.


In regards the Switchboard  color. The general interior of the Rear Torpedo area was Ivory and all the wartime and postwar photos of Rotary (U552) and Rectangular (U995 Kaura) Switchboards looks a White color with Black controls. Or maybe it is a very light grey?


Even though U995 museum colors are now medium grey.


So would White with Black controls be correct for Wartime?


Also if White was there any reason for this color when most other equipment was a generally a shade of Grey?
Thanks.

[tore]

Raymic1
The general impression of the VIIC interiors is grey and the machinery a slighter darker shade of grey. I guess the impression of Ivory on the black and white photos could derive from the reflection of the flash. The fancy green colours as on the main engines on museums U 995 might be a postwar influence from the commercial fleet as they used very often such colours. As space was a problem you did not stock a big selection of paint containers. The switchboards were light grey and the manoeuvre-wheels (switches) black. A big variation of colourstripes could be seen on the pipes, they were the colours codes use for identification for the various pipes as can be seen on the plate below.
Tore

[Katuna]

Does anyone know if there is a color version of the pipe identification code plate?

[tore]

Katuna.
We did not use the German colourcode for the pipings, but I have a short (and incomplete) explaination of the system which migth be of some help.
Tore

[Katuna]

Thank you Tore, I really appreciate it.


I remember seeing a reference to a color version of the German codes in my research but I never found it. It's out there somewhere. Would add a nice detail, as well as a little bit of color to the model.

[Raymic1]

Hello Mr Tore. I hope you are well.
For over 8 years it seems you have been sharing your photos and notes. For this we heart-fully thank you.It had been fantastic in-site into your first hand accounts of life on a Type VIIC.
I was just wondering.
As has been discussed for some reason hundreds of early pictures have disappeared  from your Posts or can no longer be opened which is a bit frustrating when we read the early posts.
At your convenience I wonder if you could just randomly reload any and all pictures you may like to share again? They don't have to be in any order.Any picture or any Uboat subject no matter.
I don't want to make it an onerous task for you, just what you feel like sharing in your own time would be fantastic to add to the history of the Uboat story.
Thank you
Mike
New Zealand