Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Thank you Mr. Tore,


I updated Skizzenbuch and uploaded the latest PDF file to dropbox...


Regards,
Don_

[tore]

Don.
Your Skizzenbuch page 40 give a description and a photo which might give a wrong understanding, further the plate 7 and plate 17 could give an impression that venting and blowing Q is done via two pipelines.
 Both systems are combined in one crossoverline between port and starboard Q tank. On starboard side you have the red wheel which is the main blowingvalve for both tanks and is not involved in the venting as your nomination on the photo :"air supply, ventvalve drive shaft".
 When the main blowingair valve is opened air is admitted to the common crossoverpipe and to both tanks via the hullvalves and both Q`s are blown..
 When venting, the master blowvalve is shut and the common portside ventvalve is open and vent the common crossoverpipe for both tanks into the boat via the common muffler.
Thus blowing both Q tanks is only done by the red handwheel on starboard side and venting both Q's is only done on the port side by the lower T handle ventvalve to the muffler.
Below is a sketch trying to explain my remark.
Tore

[Don Prince]

Hello Mr. Tore,


I don't know if you have the current version of Skizzenbuch with 322 pages.  I believe we covered the issue of the Q tanks and there was an adder page 43 in the latest version.  However, If page 43 does not look good, then I will definitely go and replace it.  Can you download the latest version and let me know if you see any problems with page 43?


Skizzenbuch has started to increase in size; which is a good thing because I'm getting really good information.  Just Today, I got a response from the Uboote Museum in Cuxhaven Germany and they are going to copy an Electrical Engineering Manual with supporting drawings.  This is something that Maciek and I have been searching for in the past several years.  I can see there will be easily a dozen or more added pages.


Regards,
Don_

[tore]

Don.
Sorry I missed your latest version of the Skizzenbuch where you have the correct system of the Q. A minor remark is that you have marked the handles for the diff. manometer cocks as cut off valves may be you should add " for the diff manometer". I`ll start checking the latest version of the Skizzenbuch as from now. It is quite a comprehensive work to get everything into such a book and I guess you shall end up with a few extra pages before it is finished.
Good to hear you are getting along with your Electrical Engineering Manual and supporting drawings. Kindly advice if my high Voltage scheme is still needed when I am back to civilization in October.
Tore

[Don Prince]

Thank You Mr. Tore,


I corrected the photo labeling on page 44 and updated Skizzenbuch...


Regards,
Don_

[tore]

Don.
I hope I have the latest edition of your Skizzenbuch and am referring to page 157. On your image of the outer and inner main exhaustvalves it looks as you have mixed the inner valve with the outer. The inner valve is the aftmost red wheel operating a flapvalve being fully open when the relevant diesel is blowing the ballasttanks. The outer flapvalve just before the exhaust silencer is used for regulating the exhaust backpressure for blowing.
 The inner valve has a double turning shaft one acting as a fulcrum for the flapvalve, the other as a shaft ending in a square outside the gearcasing. On this square you can put a ratchet bar for grinding the valvedisc against its seat by hand. Very much the same way as the outer exhaustvalve except the latter in driven by the pneumatic motor. See image below.
Tore

[Don Prince]

Hello Mr. Tore,


I am in the process of correcting page 157...  When the engine room engineer is adjusting the Exhaust Silencer flap valve to establish the correct blowing pressure of 1.5 atm is he using the pressure gauge mounted on the back bulkhead (barely visible)?  What is the gauge ahead of it (most prominent in the photo) used for?


Thanks for picking out this error on my part.  I guess I was fixated on the pressure gauge in the center of the photo...


Regards,
Don_

[tore]

Don.
I don`t think so Don, this manometer is marked for the normal LP air pressure and I guess it is used for the pneumatic/air system of the main clutches. As far as I remember, the exhaustpressure would be checked by the manometer in the instrument panel up front of the engines. I am not sure if I understand you question referring to the most prominent gauge are you referring to the fuelmeter for the day/settlingtank?
Tore

[tore]

Don.
In your Skizzenbuch page 59 you are stating: "note the internal aux. luboil pump is not used to fill the fuel oiltanks". Under normal circumstances the fuelling station is able to furnish adequate fuellingpressure, however the ¨VIIC  systems are generally  quite diversified and able to handle a number of situations. F.inst. if you are fuelling from a source not able to supply adequate pressure to force out the compensatingwater you use the aux luboil pump. Likewise if you for some reason should empty the fuel in the fueltank without being able to use compensatingwater pressure f.inst during docking or maintenance, you might use the aux. luboilpump as seen on my two sketches below.
Tore

[Don Prince]

Hello again Mr. Tore,


I made the corrections to Page 157 and that location is in the 2nd third of the book (not a problem).  I had an issue with "MS Word" crashing and corrupting my file, so I had to break up Skizzenbuch into 3 parts.  I also corrected page 59 and added your excellent drawing, but that involved deleting a print and moving things around to get everything in the 1st third of the book's 108 pages.  Pages 57 through 69 were moved or changed.  However, I believe the changes make everything flow much better as far as information and presentation goes.


I uploaded the latest version of Skizzenbuch to dropbox with all your changes to date...


I really appreciate all your extra effort in making Skizzenbuch a good source of information on the type VIIC U-Boat.  At 322 pages, I have to go back and read what I had written (I think sometimes I have a senior moment!)....


Kind regards,
Don_

[tore]

Don.
You idea of a Skizzenbuch is great but ambicious as it is almost impossible to incorporate every thing. To day I am referring to page 76 and your description of the saddle tanks fuel configuration plate 16. May be a short explanation of the system would be helpful. As mentioned before plate 16 is a bit unclear with regard to which valves are inside and outside the pressurehull. As a rule the valves operated inside the pressurehull have a double line crossing the valvespindle. However the Kingstons marked on plate 16 have not.
The venting system of the saddletanks has a special arrangement as the tanks a stretched over a long area of the submarine. As the tanks have a common main vent appr. midships this create a problem particulary when diving at a steep angle down as air shall be trapped in the aftermost part of saddletank 2 port and stb. ,see my sketch below. To overcome this is a small crossover residue ventpipe having a common ventvalve in the aft part of the tank. The vent can be operated both from the controlroom and the engine room. Like the common main ventpipe for the saddletanks the residue ventpipe has individual gatevalves to be shut in fuelconfiguration. These valves are, like the gatevalves in the mainventpipe, operated from the casingdeck outside the pressure hull.
The gatevalve on the photo you are assuming is the ventpipe gatevalve D1 for the residue venting, is the port forward engineroom bulkhead valve for the shipventilationsystem and has nothing to do with the saddletank residueventing.
Tore

[Don Prince]

Hello Mr. Tore,


I know I can't put everything in Skizzenbuch.  However, my idea is to create a single book that gives the reader (now me!) a good understanding of the design and functionality of the Type VIIC U-Boat.  I am especially grateful to you because I don't believe there is anyone else left with the knowledge you have on the Type VIIC U-Boat.


I have updated Skizzenbuch with your latest suggestions, and posted the latest Skizzenbuck into dropbox...


Regards,
Don_


PS:  I don't believe the U-Boote-Museum has the large ship print that you have because that came from the builder.  Their books are of the Kriegsmarine training variety...

[tore]

Don.
I have just had a quick glance on your latest edition of your Skizzenbuch and have a few minor remarks. On page 40 you have still a photo marked as valves controlling the Q tanks.The starboard main blowingvalve is marked as ventvalve drive shaft, as this is wrong I suggest you name it the common main blowing valve for Q. On the photo of the port controllingvalves for Q is the main vent valve marked as valve in the line to the muffler below, which is correct, but I believe it would be easier to understand if same is named as the common main vent valve for Q tanks.
On page 157 the handwheels for the inner and outer main (Group) exhaustvalves are interchanged. The aft wheels marked as external flapvalves are the internal, and the forwards marked as internal flapvalves are the outer flapvalves before the silencers . I guess the confusion is due to my photo where I for some reason have erroneously have marked the inner flapvave gearsegment as Casing for EXTERNAL EXHAUST FLAPVALVE SHUTTING GEAR SEGMENT, it should be internal, please correct. Sorry
Tore

[Don Prince]

Hello Mr. Tore,


I corrected page 40 and 41 with your recommendations...  Thank you.


The right insert photo of the "Casing for the External exhaust flap valve gear segment" looks to be positioned near the aft engine room bulkhead, and you can see part of the pneumatic motor.  This looks to be correct to me???  Am I missing something?


Both the external and the internal exhaust flap valve are manually controlled by the hand-wheels which turns a shaft with a worm gear to drive a segment that opens or closes the exhaust flap valve.  Is this correct?


If so, then would this photo be OK?


Regards,
Don_

[Don Prince]

Hello Mr. Tore'


After reviewing your diagram of the flap valves, I believe there is a gear in the casing and not a segment.  I think that part needs to be changed,,,  What do you thing?


Regards,
Don_