# The Type VIIC Untersee Boot



## SoD Stitch (Apr 22, 2008)

Lately, I've developed a healthy obsession for U-Boats, but I don't know why; maybe it's because I just got done watching _Das Boot_ again. Anybody else interested in them? Some fascinating things I've learned quite recently about U-boats that had never occured to me before:

1. The streamlined, rakish outside of the U-boat that you usually see in pictures movies is just an outer shell of sheetmetal; the heart of the U-boat is inside of the "hull", and is actually a cylindrical tube with all of the important stuff inside. The streamlined skin of the U-boat is attached to the center pressure hull by bracing; only about half of the volume of a U-boats hull is pressurized, the rest is open to the ocean water.

2. The fuel oil (typically diesel) is carried by the saddle tanks on the outside of the pressure hull, and are open on the bottom to the sea water. Since fuel oil is lighter than water (but not by not much), it stays in the top of the saddle tanks; it is actually "floating" on top of the seawater. As the U-boat uses the fuel oil by drawing it from the top of the saddle tanks, it is replaced by seawater, thereby maintaining the U-boats bouyancy.

3. All U-boats carried an anchor, just like a surface vehicle, though they were rarely used, since they usually tied up to a pier or a submarine pen.

4. The "heart" of the U-boat, the control room, doubled as an escape chamber if the U-boat sank; seawater was let into the control room up to the level of the conning tower, and pressurized air was released into the conning tower to equalize the pressure of the outside water. In this way, the hatch could be opened; otherwise, the pressure of the seawater would prevent the hatch from being opened. After the hatch was opened and the conning tower was submerged, the seamen were to swim out out of the conning tower hatch and up to the surface one by one.

5. The keel of a Type VII U-boat was composed mostly of iron bars to act as ballast, therby keeping the U-boat upright in even the most violent sea states.

6. Extra torpedoes were stored in the interstitial spaces between the pressure hull and the horizontal decking of the U-boat on the Type IX; however, tranferring the torpedoes from the outside of the pressure hull to the inside was a time-consuming task, and left the U-boat vulnerable for several hours on the surface. The Type VII carried all of her torpedoes on the inside of the pressure hull, with the extras stored "below deck" in the torpedo rooms. The U-boatmen billeted in the forward torpedo room actually looked forward to "action", as it meant there would be more elbow room in the forward torpedo room where most of them lived.

7. The main air inlet for the two on-board diesels was actually right underneath the "Wintergarten", the extra platform to the rear of the conning tower that usually carried the AA defenses (on later models of the U-boats; earlier models, pre-'42, had no AA armament). A large (approx. 40cm) duct brought fresh air from underneath the Wintergarten to the engine room for the diesels; this had to be opened before the diesels were started, or they would soon suck up all of the air inside of the U-boat and rupture seamen's eardrums.

If anybody else has any other interesting facts concerning U-boats, or simply wants to learn more about these interesting vessels, please contribute to this thread. I will do my best to post more interesting tidbits as I learn more about U-boats and, in particular, the Type VIIC.


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## A4K (Apr 22, 2008)

Interesting stuff, mate!


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## Glider (Apr 22, 2008)

I am pretty sure that this link will have all the information that you will ever want on the structure of the Type VII U Boat

U-boat Archive - U-570 - ONI Report


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## Lucky13 (Apr 22, 2008)

I'm a sucker for subs as well buddy....love those Type IX and Gato classes!


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## Soren (Apr 28, 2008)

CHeck out Uboat.net, it's got the most reliable complete info out there.


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## HerrKaleut (May 26, 2009)

Hi SoD Stitch, Correct on location of main induction valve and trunking.( the technical name for the platform was the Turm O...no idea what o stood for!). However the type V11 boats carried A.A. in the form of a 2c.m. flugzeugabwehrkanone from the very begining (originaly on the after deck casing but onto the platform by the start of the war. This remained the type V11s A.A. weaponry until 1942 when the single 2c.m. gun was replaiced with a pair of mountings twin MG 151 mountings , the Turm was widened to take the twin mounts and became Turm 1 and later still a second platform was added and became Turm 2 (also called the wintergarten). However, when this flak suite was tested on U-553 it was found to be unsatisfactory and they reverted to a single 2c.m. on each platform until further developments in 1943 led to the Turm 4 and all that was entailed.
Out of interest U-338 was fitted with an experimental flak platform with twin mg 151 on the FRONT of the conning tower but that was found to be ineffective.


You would find "Type V11 U-Boats " by Robert C. Stern very helpful. Regards.


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## beaupower32 (Jun 6, 2009)

SoD Stitch said:


> 2. The fuel oil (typically diesel) is carried by the saddle tanks on the outside of the pressure hull, and are open on the bottom to the sea water. Since fuel oil is lighter than water (but not by not much), it stays in the top of the saddle tanks; it is actually "floating" on top of the seawater. As the U-boat uses the fuel oil by drawing it from the top of the saddle tanks, it is replaced by seawater, thereby maintaining the U-boats bouyancy.




I never knew this. Thanks for the info.


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## psteel (Jun 7, 2009)

I bought the translated edition of Eberhard Rossler, "The Uboat, the evolution and technical history of German Submarines"

Quite expensive , but worth the cost in my opinion.

The U-boat: The Evolution and Technical History of German Submarines


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## Crunch (Jun 7, 2009)

beaupower32 said:


> I never knew this. Thanks for the info.



Yeah, I like that one too. Interesting.


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## diddyriddick (Jun 8, 2009)

I agree with Soren-Uboat net is the best source out there. Here are some pics of a type VIIC boat lying just off of the coast here in NC. Its in about 100 feet of water, so is accessible by recreational diving.

http://www.nc-wreckdiving.com/WRECKS/U352/U352.HTML


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