Two marks on the hull of Type VII

[JAORSA]

Hello everybody!

A technical question;
could somebody say me that they are those two marks on the hull of Type VII?
so that they serve?
what function has?

Thanks

[conus00]

Siara would be the one to ask. He studied VIIC extensively.

[billp51d]

     I think you'll find that they're a mystery to everyone in the modeling community. Good luck..
                                                     Cheers/Regards, Bill

[Siara]

Bill is right- none knows what the 2 bumps are for. One think is certain- you need to sand them down, and replicate them in slightly different place ( higher ). Study the pictures to locate where the bumps should be, as Revell didnt do the homework properly.

[Rokket]

Even The Masters know not what they are...much speculation, but no answers.

This is when we need time machines. Sure, they would be useful for much, but some stuff they would just make easy. here they would be the only answer.
They are positioned slightly wrong in the Revel kit as Siara says.

[Bad Karma]

I have asked this question on a Dutch forum.

This is a answer from Jeff la Rue,

__________________________________________________________________________________________
If memory serves.....those are the (compressed air) vents for the torpedo launch system.
There should be four of them (two on each side)...
one for each forward torpedo tube.
----------------
Jeffrey W. LaRue
___________________________________________________________________________________________

Here is a pic of the decompression tanks.

[billp51d]

      Originally I thought the same that they were to exhaust the spent gases from fireing torpedoes but I was later told that that these gases were recaptured so that bubbles would not give away the u-boat location.
      Doing an overlay of the pressure hull and the 4 cylinders even suggest that these "bumps" are somehow connected, however I was told not.
      After scratching my head and pondering "what else could they be?" i've finally concluded that.....
      1. They're for side view mirrrors ?
      2. Perhaps .... turn signals ?
      3. Relief tubes for the crew ?
     And so the mystery continues.....
                       Cheers/Regards ...Bill

[Rokket]

Yes, i USN boats the air and water were sucked back into a Water Tank Round...venting would be a DEAD give-away. I think bill's right, turn signals!

[Pat]

How about some sort of pressure relif valve?  Like when trucks with airbrakes 'fart' every once in whileto let off excess pressure since they have to keep constantly pumping air into them to stay within a certain range.

If that was the case, they wouldn't let off much air at any given use, so not much chance of being spotted.

[NZSnowman]

I to also thought about the compressed air vents for the torpedo but I have look at the Torpedo tube firing, venting, flooding and drainage systems schematics from U-570 and can not found any outlet through the pressure hull. The other thing I ask myself if it is a compressed air vents where is the vent for the stern torpedo?

Below is a list of opening in the pressure hull in the bow section that were are four of. My feeling it must be the eight openings for the Flooding torpedo tubes and Draining for torpedo tubes

4x Torpedo tube outer doors
4x Passive sonar array
4x Transmitter for underwater telephone
4x Mine ejection
4x Flooding torpedo tubes
4x Draining for torpedo tubes
4x Torpedo nozzle forward

http://www.uboatarchive.net/U-570Plate25.htm

[Pat]

I agree, those look like reasonable suspects as to their use.  But the same question applies: where are they for the stern tube?

[Rokket]

Actually, it probably isn't for torps - to prevent airbubbles from escaping (tell-tales), the water and air were sucked back inside the sub. In Gatos it could go to a tank for this purpose, or sent to ballast tanks. (also vented outside, but that would be less common, as in, only do-able when not going to be seen).

[NZSnowman]

I am currectly reading Iron Coffins by Herbert A Werner

Here what he writes on page 38

"The compressed air, which had activated the large pinlock that expelled the torpedoes, was released into the boat instead of the water, thus avoiding the bubbly swell on the surface that had revealed the position of submerged U-boat during World War I."

 

[SnakeDoc]

"The compressed air, which had activated the large pinlock that expelled the torpedoes, was released into the boat instead of the water, thus avoiding the bubbly swell on the surface that had revealed the position of submerged U-boat during World War I."

http://uboatarchive.net/KTBNotesArmament.htm

[Don in Cincinnati]

I am currectly reading Iron Coffins by Herbert A Werner

Here what he writes on page 38

"The compressed air, which had activated the large pinlock that expelled the torpedoes, was released into the boat instead of the water, thus avoiding the bubbly swell on the surface that had revealed the position of submerged U-boat during World War I."

 

I am at as much of a loss as to the function of the two "bumps" as everyone else, but here is another piece that may help to eventually solve the puzzle. On page 36 of Showell's book U-Boats in Camera the top picture on the page shows a type VII in drydock and the two bumps can be seen from a 3/4 rear angle. They are clearly some sort of tube and not just a solid mass.