Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Hello Mr. Tore and Maciek,


The fuel transfer that I want to document would be from internal fuel storage tank like 1 IB. The reason for my interest is that when schnorchelling the cooling water pressure head to/from the internal fuel tanks is too high for the gravity tanks (14 mwc). So a directive was issued that when schnorchelling only the saddle tanks may be used as a fuel source to the gravity tank.


During the late war period, U-Boats with schnorchels were pretty much below the surface bound. Therefore, a fuel oil saddle tank low situation may exist, and then a the need to transfer fuel oil to the saddle tanks.


On Plan 9, internal tank 1 IB has a hose connection "b3" where the source is the internal storage tank 1 IB. If there was a hose connection between "b3" and "c" at the Auxiliary lubricating oil pump head, then could the pump transfer fuel through the tank selection valve chest and then to the saddle tanks? The cooling water pressure head already exists for the internal storage tank, and it's always available to the saddle tanks.  It looks to me like this would be sort of a refueling situation for the saddle tanks, and the cooling water in the saddle tanks would be forced to exit at the header tank overflow...


Does this drawing look OK?


Regards,
Don_

[tore]

Don.
I am not familiar with the German schnorchelling instructions and give my comments based on my experience. In general the internal fueloil tanks are designed for watercompensating which have many advantages. The high compensating water pressure while schnorcheling is of course a problem as the testpressure for the internal fueltanks is 8 mwc. However I don`t see the need for using the saddle ballast/fuel tanks while schnorcheling. Although your proposed system I guess would work, I don`t think it would be nessecary. What you really need is to top up the header settling/day tank in the engine room. The volume of this tank is appr. 365 liters. I would prefer to use the watercompensating system isolated from the external headertank in the wintergarten, using the handcoolingwater pump in the engine room to allow compensating water to enter any of the two internal fuel storage tanks, using the system already installed and cracking the intakevalve c1in the crossover line as per my sketch below. I estimate it would take about 1/2 hour to top up the daytank. Kindly note the external fueloil storage tanks have  reliefvalves both for overpressure and underpressure.
Tore

[SnakeDoc]

Hi Don,

The fuel transfer that I want to document would be from internal fuel storage tank like 1 IB. The reason for my interest is that when schnorchelling the cooling water pressure head to/from the internal fuel tanks is too high for the gravity tanks (14 mwc). So a directive was issued that when schnorchelling only the saddle tanks may be used as a fuel source to the gravity tank.

During the late war period, U-Boats with schnorchels were pretty much below the surface bound. Therefore, a fuel oil saddle tank low situation may exist, and then a the need to transfer fuel oil to the saddle tanks.

I can not find the source right now, but I remember that I was reading somewhere (standing order, KTB?) that when the U-Boat was fitted with Schnorchel, the over-pressure and under-pressure valves of the internal fuel oil tanks were adjusted to make them usable  during submerged cruise.

--
Regards
Maciek

[Don Prince]

Hello Mr. Tore and Maciek,


Mr. Tore - how often would you have to spend 1/2 hour hand pumping water on a Gravity Tank cycle? Also from what I remember, you did not usually have fuel oil in the saddle tanks...


Maciek - the article is at  www.uboatarchive.net/U-413INT.htm  and on page 19.


Regards,
Don_

[tore]

Don, you are right we did not use the saddletanks as fueltanks and I have tried to remember how we transferred the fuel from the inner tanks to the settlingtank in the engineroom while schnorcheling. I guess we used the normal compensatingwatersystem, which by schnorcheling is estimated to have an additional 0,6 m WC pressure to the normal surface cruisingpressure.
The internal compensatingsystem and fuelstorage tanks have as previously stated a safetyvalve at the pressurehull intake, this valve can be adjusted, but I guess we cracked the hullvalve throttling the pressure when filling the settling/daytank at a volume of half a barrel, this was done in a short time. In addition to the intake pipe reliefvalve, each internal fuel storagetank were equipped with another safety arrangement consisting of a valvechest containing an overpressure and an underpressure reliefvalve to prevent damage to the tank.
As far as I could estimate the fuel consumption of one diesel at schnorcheling would be appr. 220 litres/hour which would mean a topping up of the settlingtank a little more than twice a watch. I think Macieks indication of seeing an info on adjusting the safetyvalves migth be correct as we are talking about minor pressures.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


I have done a major rewrite of Skizzenbuch where information has been updated and the pages are arranged to follow a logical sequence. I have backgrounds for all the plan pages of either photos or colors.


The latest version of Skizzenbuch 11 x 17 - M.pdf has been uploaded to Dropbox.


Herrn Klaus Mattes and Jak P. Mallmann Showell are working with two German Museums and several German U-Boat Interest Groups about Skizzenbuch.  They seem to be impressed with the scope and depth of our work.  I may have more info in a week or so.


Regards,
Don_


PS - Klaus Mattes wrote a book "Die Seehunde"...

[VIC20]

Great book, I have it in my little U-boat library. 

[karel]

Don Prince.  Is there any way i could buy an early access for Skizzenbuch from you?
I could really use it as a technical reference for my game. Originally i planned to wait until spring and buy from publisher, but that option is not there anymore. Having an access to Skizzenbuch would help me make a better game. I would also be happy to credit your name and book in my game if this is something that would be an interest for you.

VIC20. We spoke over email 2-3 years ago when i asked you for some technical advice. I have not forgotten my promise. If the game quality holds up from your perspective and if you wish, i can credit your name also.

Tore and Maciek
Would like to make you an exact same offer. Would be an honour to have your names also there.

[Don Prince]

Hello Karel,


Give me about a month, Klaus and Jak are working with several German U-Boat support groups and two museums promoting Skizzenbuch. I don't believe there will be any legal distribution issued because I am not asking for any monetary compensation for Skizzenbuch; my work stands on its own merit! Several years ago when I started compiling Skizzenbuch, it was intended only for my personal library; I am not the U-Boat expert like Mr. Tore and Maciek. I purchased a leather covered metal post binder for my library with gold lettering on the front cover. The binder determined the 1.75 inch spacing on the 11x17 inch binding side page layout.


My requirement: The Skizzenbuck PDF file is not protected form modification. This was done intentionally, so Mr. Tore and Maciek could modify Skizzenbuck if they so desired. However, I have only made changes to the Skizzenbuch 6 Microsoft Word files which are converted to PDF files. and then the PDF files are merged into 1 PDF file. If I give you access to my Dorpbox folder account which contains the "Skizzenmbuch 11x17 - M.pdf" file, then this file will not be distributed without my permission.


Later, I plan on purchasing "CopySafe" PDF protection software (very expensive) which encrypts the PDF file and embeds a viewer in the file. Also, it provides the PDF author with a host of other options.


Kind regards,
Don_

[Don Prince]

Hello Mr. Tore,


I believe it was mentioned that the cooling water pump in the e-room had some fittings to allow the introduction of anti-corrosion oil...  I can see a direct path through the cooling water valve chest, but it looks like the anti-corrosion oil only makes one pass through the pipes and the diesel engines. Then it goes through the cooling water system; the mufflers and to the header tank and out to sea.  Is that correct? How often was the anti-corrosion treatment done?


Regards,
Don_

[tore]

Don.
In spite of a few pipebends having severe corrosions I can not remember we used anticorresion oil. I believe the oil was pumped into the coolingwatersystem by the coolingwater handpump stb side in front of the mainengine, a spesial armed oilresistent hose was used, diameter 38mm  and length about 2 meters. Below is an image showing the system, as the plate 13 for the GW engine is not showing a correct system, I include the plate 13 a which is the  MAN system however the anticorrosion oil inlet is the same for both enginetypes. . As far as I know the anticorrosion oil came in a barrel and the end of the hose was put in the barrel.
Tore

[karel]

Don.

Thank you. I can wait a month, no problem. I am shifting some stuff around and work on sound and lighting for a while and shall return back on to systems when i have access to Skizzenbuch.
Just let me know in private message if you are ready. I am really excited for this and thank you again, this makes my life so much easier.

[Don Prince]

Hello Mr. Tore,


It looks like they could hand pumped anti-corrosion oil into the cooling water valve chest while the diesel engines were running. The hand pump's pressure head would be greater than that of the two attached diesel cooling water pump's pressure head, so the anti-corrosion oil would be mixed with the cooling water as it is pumped into the cooling water valve chest; then its piped to the lubricating oil coolers and on to the diesel engines.


Is my summery correct?


Regards,
Don_

[tore]

Don.
I guess your understanding of the anticorrosionsystem is correct. The procedure was to start the engines and let them idle, then "injecting" the anticorrosion oil by the hand pump. The oil used was an emulsifying oil having the German naval specification Zd M17. The "contaminated" coolingwater could be drained via cock f1 to the dirty luboiltank aft of the luboil systemtanks.
Tore

[Don Prince]

Hello Mr. Tore and Maciek,


I have made some additional changes to Skizzenbuch and added an "Index." The new file is in my Dropbox account folder...


Skizzenbuch 11 x 17 - M + I.pdf


Regards,
Don_