My apology to the Subcommittee members for wrong info in SCR issue #60...

[don prince]

The SCR published in March of 2005 had my following article... German U-Boat Type VII C; The ballast System and personal research and observations by Don Prince. Wow, that article was really wrong in so many ways!

Analysis: Don't believe everything you read on the Internet!

References: Over the past two years, I have been communicating with Mr. Tore-Berg Nielsen (Norway) and Mr. Maciek Florek (Poland) about how the U-Boat Type VII C actually functions and my education was really eye opening. The ballast system was far more complicated than my previous understanding. Maciek has translated many of the different Official German U-Boat manuals and his knowledge on the technical aspects in tremendous. Mr. Tore was an Engineering Officer in the Norwegian Navy and his commission was on-board U-995 (VII C/41) and U-926 (VII C) in the early 50's. This gentleman knows in detail about every pipe and valve location, the diesel engine and compressor design, and most important the everyday life and challenges facing an engineering officer in charge of the U-Boat.

The moral to my story: I'm a recovering-expert on the Type VII C U-Boat, who now realizes that I'm just a student...

Kind regards,
Don_

[PaulC]

Don, I agree. We're all students and the opportunity to learn something new never ends. This sounds like a great opportunity to write an updated article.

[JWLaRue]

Don, sounds like an excellent reason for an updated article from you.....?

-Jeff

[don prince]

Hello Paul and Jeff,

The article in SCR #60...In question was the design of MBT 1 through MBT 5. MBT 1 and MBT 5 have vent valves located on the upper area of the tanks and there are open slots at the bottom of these tanks. So they can hold air internal. The bow and stern buoyancy tanks are not part of the ballast system; there only purpose was to prevent the bow or stern of the U-Boat from under-cutting in heavy seas.

Saddle tanks MBT 2 and MBT 4 could be configured in two ways; as reserve fuel oil tanks or ballast tanks:

1. In the reserve fuel oil configuration MBT 2 and MBT 4 have their vent passage shut by external gate valves and the Kingston flood valves are shut. Now, water taken in to cool the diesel engines is piped to cool the jacketed exhaust lines and the mufflers. In addition, some hot water is piped to the header tank located under the winter garden. The header tank provides compensation water to all fuel oil tanks (except RFO Regulating Tank #1 which uses compressed air); so the used fuel is displaced with the cooling water and the fuel oil floats to the top in the tanks. The reason for the compensating water; if the tanks were empty, then the weight loss would not allow the U-Boat to dive (too much buoyancy)!

2. In the ballast configuration MBT 2, MBT3, and MBT4 Kingston flood valves are always open during the entire war patrol. During a dive, MBT 2 through MBT 5 are immediately flooded by opening the vents. MBT 1 is slightly delayed in order to get the U-Boat set at a dive angle of 7 degrees. The bow and the top of the bridge wind deflector simultaneously go below the surface. This assures the dual props are deep enough to drive the U-Boat under water.

Note – the negative dive tank was flooded while the U-Boat was previously submerged and surfacing at a depth of 10 meters. The reason for the flooded negative buoyancy tank was to quickly break the surface while diving and at 10 meters depth it was blown. They don't want the extra weight when submerged and to blow it at a deeper depth would require more high pressure air.

To normally surface the U-Boat it was brought up to the night/aerial periscope depth (about 12 meters) to assure there was no danger on the surface. High pressure air is admitted to all the configured ballast tanks and they are partially blown and as soon as the bridge came clear the captain and the watch went to the bridge. If all was clear, then the captain ordered the diesels started and one diesel was selected to use its exhaust to complete the blowing process. In this early surfacing process the U-Boat's meta-center is very low and prone to a roll over in heavy seas. Therefore, the order of exhaust blowing ballast tanks would be the upper tanks first, so MBT 3 would be the last tank completely blown by exhaust.

This is just a brief description of how things actually worked in the Type VII C U-Boat ballast system…

Regards,
Don_

[salmon]

Great information there...what else did you learn or as Paul and Jeff have recommended should I wait for the article, which by the way I think would be really cool!
Peace,
Tom

[JWLaRue]

Don and I had an e-mail exchange earlier today about the possibility of an updated SCR article. Right now Don is in the process of getting a book published by Schiffer Publishing that is titled "Skizzenbuch: U-Boat Type VII C Project." Since he is under contract, he is limited to what he can publish in other venues. (e.g. the SCR)

I have seen an earlier, draft review version of this book and I can say that Don has done some extensive research into how a Type VIIC U-boat is operated. It is a combination of original diagrams (think the equivalent of the NAVPERS 16160 Fleet Submarine book) along with color photos of the interior of the U-995 and written explanations of how things work.

-Jeff

[kielbasa]

I am looking forward to the book!