Tores mailbox VIIC and VIIC/41 operation and technical details

[SnakeDoc]

I looked at the photo closely and it looks like there are 5 pressure gauges (one under the red hand wheel) clustered around the main blowing valve.  Would that be a pressure gauge for each dive tank 1 through 5?

There are five gauges - the one on the top/in the middle is the pressure gauge in blowing distributor, the other four - two on each side are the pressure differential gaueges for Regelzelle Bb, Regelzelle Stb, Regelbunker Bb and Regelbunker Stb. See photo.

In addition, on your photo labeled "untertriebszelle gauges"  The large red hand-wheel is for one or both Negative Buoyancy tanks?  I don't see the same configuration on the other side...

The large red wheel is hand regulating valve for both tanks. See photo.

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Regards
Maciek

[SnakeDoc]

Hi Tore,

thank you for your answer - that was exactly what I wanted to know.

The water residue checksystem is a small pipe going down to the Kingstons and an internal cock in the CR ending into a small funnel, I believe you can see same on the photo of the port system.

Are you thinking about this line? I have marked this with green color.
I also marked lines which (if I'm not mistaken) fed differential pressure gague for Untertriebszelle Bb. The red one connects with Untertriebszelle Bb, while the blue one - with outside sea.
Unfortunately I was not able to find good photo with some cock/valve visible, which would cut off the residual water check line from the negative tank.

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Regards
Maciek

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Regards
Maciek

[Don Prince]

Hello Meciek,


Would this drawing be correct?


Regards,
Don_

[tore]

Hi Tore,

thank you for your answer - that was exactly what I wanted to know.

The water residue checksystem is a small pipe going down to the Kingstons and an internal cock in the CR ending into a small funnel, I believe you can see same on the photo of the port system.

Are you thinking about this line? I have marked this with green color.
I also marked lines which (if I'm not mistaken) fed differential pressure gague for Untertriebszelle Bb. The red one connects with Untertriebszelle Bb, while the blue one - with outside sea.
Unfortunately I was not able to find good photo with some cock/valve visible, which would cut off the residual water check line from the negative tank.

--
Regards
Maciek

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Regards
Maciek

Hi Maciek.
Yes your green line could be the residual water checkpipe. The checkvalve might be situated further up as indicated on my photo below. I am not sure about your assumption for the diff manometerpipes though. As you see from my photo it looks as if both  pipes goes only to the manometer.
Tore

[tore]

Hello Meciek,


Would this drawing be correct?


Regards,
Don_

Don.
I am not sure, as the  two systems blowing and venting is combined in one on board, this can be confusing as on plate 17 and 7 they are drawn as separate system see my photo below. The blowing system on plate 17 starts with the blowing valve (hand control valve) having air supply from the main distribution manifold. After this valve is the reliefvalve, a manometer connection and a drain. This is a standard package for all the airblowing system. After this system is a shut off valve. It seems to me as you have switched  the hand control valve to this shut off valve. When the drawing and the real world is not corresponding it is usually best to follow the real world. It is almost impossible to check the system locally based on the photos we have available, however we can not see any plain manometer, but clearly a differential manometer which we can assume is hooked up as on the visible port side, the reliefvalve is visible so that is OK. The shut off valve I cannot see but I am almost sure it is there together with the connection to what I would call the common venting/blowing pipe.
Tore

[Don Prince]

Hi Meciek,


Thanks for the quick response....  I did a little art work to enhance the previous photo.  Does it look OK?


Regards,
Don_

[tore]

Don
Not bad. If you follow the port ventpipe down it disappears behind a small steel cabinet right underneath i the pipe ends in a fairly large Box which I believe is the  venting muffler for the two Q tanks, see the bad photo below.
Tore

[tore]

Don.
As a final touch I should probably mention that I believe the external floodvalve for Q is  not a  Kingston, square flapvalve, as on the fuel/ ballast saddletanks 4 and 2, but rather a valve behind a large square grating next to the aft Kingston on ballasttanks 4 port and stb. On the photo below you can see what I assume, my first thoughts were that this grating was connected to the fuel compensatingsystem but I believe the above is a better theory, you can see the round valve outlet behind the grating. Thus I suggest you rename floodvalve driveshaft: Handwheel external floodvalve . As a curiosity I have found out that the flood area of these valves are 0.24 m3 and with Q fully blown you have a residue water in the tanks of 0,16m3, not much.
Tore

[SnakeDoc]

Hi Tore,

Yes your green line could be the residual water checkpipe. The checkvalve might be situated further up as indicated on my photo below. I am not sure about your assumption for the diff manometerpipes though. As you see from my photo it looks as if both  pipes goes only to the manometer.

Thanks for your answer, I think you are right. I did not recognize relief valve.

I am not sure, as the  two systems blowing and venting is combined in one on board, this can be confusing as on plate 17 and 7 they are drawn as separate system see my photo below. The blowing system on plate 17 starts with the blowing valve (hand control valve) having air supply from the main distribution manifold. After this valve is the reliefvalve, a manometer connection and a drain. This is a standard package for all the airblowing system. After this system is a shut off valve. It seems to me as you have switched  the hand control valve to this shut off valve. When the drawing and the real world is not corresponding it is usually best to follow the real world. It is almost impossible to check the system locally based on the photos we have available, however we can not see any plain manometer, but clearly a differential manometer which we can assume is hooked up as on the visible port side, the reliefvalve is visible so that is OK. The shut off valve I cannot see but I am almost sure it is there together with the connection to what I would call the common venting/blowing pipe.

Tore, do you think, that relief valve is on the port side? Could you point, what you call the common venting/blowing line?

As a final touch I should probably mention that I believe the external floodvalve for Q is  not a  Kingston, square flapvalve, as on the fuel/ ballast saddletanks 4 and 2, but rather a valve behind a large square grating next to the aft Kingston on ballasttanks 4 port and stb. On the photo below you can see what I assume, my first thoughts were that this grating was connected to the fuel compensatingsystem but I believe the above is a better theory, you can see the round valve outlet behind the grating. Thus I suggest you rename floodvalve driveshaft: Handwheel external floodvalve . As a curiosity I have found out that the flood area of these valves are 0.24 m3 and with Q fully blown you have a residue water in the tanks of 0,16m3, not much.

I think you are close with your assumptions. I believe that description of the negative tank's flood valves in the type IXC report can be helpful:

The negative tank flood valve is a mushroom valve opening outboard.  The valve disc is provided with a screw thread, and is raised or lowered by rotating the valve spindle which is threaded into the stem portion of the disc casting.  The spindle is fitted with a collar and ball bearings to serve as a carrier for the vent valve disc.  When turning the spindle, guides prevent the disc from turning.  The valve is operated by means of a hand crank from within the vessel.

http://uboatarchive.net/DesignStudiesTypeIXC.htm


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Thanks, regards
Maciek

[Don Prince]

Gentlemen,


Just how many people were required to be in the Control Room on a dive?


1 - Captian
2 - Chief Engineer
3 - Navigator
4 - 2 x Plainsmen
5 - Rudderman
6 - 2 x Q tanks (Port & Stb)
7 - 2 x saddle tanks (D2) Port & stb
8 - 2 x saddle tanks (D4) Port & stb
9 - 1 control D1
10 - 1 control D3
11 - 1 control D5


I count 15 people; it sure looks crowded to me.  Then again, on a crash dive you have people attempting to get to the bow of the U-boat.  They sure could use a computer system with sequenced controlled servos to do all those manual functions!!!

[Don Prince]

Hello Mr. Tore and Maciek,


I read your comments about the Negative Buoyancy tank and the different valve system.  I made some changes to Mr. Tore's drawing.  What do you think?


Regards,
Don_

[Don Prince]

Hello Mr. Tore,


"the flood area of these valves are 0.24 m3 and with Q fully blown you have a residue water in the tanks of 0,16m3, not much."

Should the flooding area of the valves be 0.24 m2 (square meters and not cubic meters)?

Regards,
Don_

[tore]

Maciek.
Thanks for your finding of the description of the Q floodingvalve as executed an a IX C I think it could be approximately similar to a VIIC.
Normally you would have a reliefvalve close to each tank as a protection of the tank, so I Guess stb Q would be the same as port. Common venting/blowingline is simply the two crossover pipes on plate 7 and 17 merged in one pipe see photo below.
Tore

[tore]

 ;DHi Don.
You are of course right, the floodarea should be in m2 not m3, my old stiff finger hit the adjacent 3 without my notice.
Tore

[tore]

Don.
I Guess manning of the controlroom varies. On your list you have missed a few. The most important man would be the NO 1 the officer second in comand of the CO, CR engineer, a petty officer who amongst other jobs is in charge of the blowingdistribution panel, thus blowing the tanks, the trim/pumpman, the chief electrician and then the torpedo officer only to mention a few in addition to your list.
Tore