Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Jon's questions on the hatches recalls my memories of the procedure for opening same after a long submerging, may be 30 hours or so. On a long time submerged situation everybody except people on watch, the CO and me was in bed using minimum of oxygen. The increased CO2 content in the air made everybody panting heavily. After a strenuous day it happened that an allowance of one cigarette per man was given ( crazy ) but mostly the match would not burn anyhow. When surfacing the CO on the top ladder having a man with a firm grip on his legs, carefully put the catch of the tophatch in position, turned the hatchwheel and the hatch cracked open letting the overpressure out so you felt it heavily on your eardrums. Mostly the foul air in the compartments turned into fog at the quick pressure release before the tophatch was fully open. The overpressure in the sub was due to various air leakages and inboard venting, but mostly by using the airmotor for the outboard group exhaustvalve grinders at the moment of diving.
Tore

[tore]

Falo has sheared some of his excellent photos from the Laboe U 995 showing details of the present days condition of the U 995. As we have mentioned many times before the museum version of U 995 today should not be used as reference for a correct version of a  VIIC/41 and particularly not the original U 995. I shall try ( during some time) to give some comments as to the details partly based on Falos photos. Falos photo shows a very good detail of the Kingstons (Flutklappen) for main ballast tank 3. I have seen many strange modellers interpretation of these flapvalves one is shown on the picture below. The photo shows the Kingstons shut and the nuts of the seating is clearly visible.
As you see the Kingstones of mbt 3 opens outwards because when shut they are a part of the pressurehull in contradiction to the ballast saddle tanks 2 and 4 where the Kingstons opens inwards being not a part of the pressure hull and as the tanks are used as spare fueltanks as well. So if you want to make your model in a ready for sea execution the Kingstons of mbt 3 should be open and if there is fuel in the saddletanks the Kingstons of same should be shut otherwise open. By the way the Kingstons got the name after a British engineer Kingston who invented the valve, I guess latter part of 1890
The other item I shall mention in my post today is the propeller/rudderguard which is missing. In this area you should include zinc sacrificing elements, this detail is very often forgotten and is an element for corrosion protection. They should not be painted but have the zinc colour, see my picture below.
Tore

[tore]

In December 2012 we discussed the seawatercompensating of the saddle fueltanks, particularly the two positioned footvalve in the compensatingpipe connected either to the bottom of the saddletank or alternatively to a "compartment" directly in connection with the sea. We could not trace that "compartment". I believe Falos detailed photos have revealed the arrangement. If you see on the photo below it is a fairly large rectangular grating next to the Kingstons in port and starboard no2 and 4 saddletanks. As the very detailed photo shows the pipeopening behind the grating I believe this is the described "chamber"and the pipe is the direct seaconnection to the compensatingsystem.
Tore

[tore]

Some of the photos sheared by Falo shows the peculiar "hullgutters" of the museum U 995. Where the sheet plating and the saddletank fairing joins the pressurehull there are some void spaces which collect rainwaters. This obviously created some problem for the museumspeople so they made drain cutouts in the plating and to prevent rustbleeding they welded a U-shaped steelbar as gutter, see photos below. This has nothing to do with the original design of the VIIC-VIIC/41s. Nevertheless I have seen modellers making painstaking copies of the gutters which have nothing to do on a VIIC model unless it is a model of the museum U-995 of course.
Tore

[tore]

Another of Falos detailed photos shows the "Pillenwerfer"slit and reveals a rare view of the outer cap of the ejector. The "Pillenwerfer" or ejector is a common device of a submarine. It is used for many purposes and is merely a steeltube having hinged caps in both ends and an interlock prevent the outer cap to be opened unless the inner cap is shut. The tube has a drain- and ejectingair connection. Inside is a piston having a guiderod through the inner cap. The ejector is charged with different types of canisters or signal rockets making possible for the submarine to send visible signals to the surface. A common canister used during WW2 was filled with magnesium pellets which was ejected when a submarine was Asdic hunted. As the canister was ejected the magnesium pellets came in contact with the seawater and the chemical reaction created a large amount of bubbles which gave a false echo on the Asdic. During exercises very often a signalrocket was ejected indicating a torpedo shot.
Tore

[NZSnowman]

Tore/Maciek

Oxygen system within engine room. Do you guys know:

• Where the manifold is located?
• Where the Exhaust Air Duct is located?
• Where are valves 'b' are located?

Thanks, Simon.
http://www.uboatarchive.net/U-570Plate20.htm
 

[NZSnowman]

Tore/Maciek

Oxygen system within engine room. Do you guys know:

• Where the manifold is located?
• Where the Exhaust Air Duct is located?
• Where are valves 'b' are located?

Thanks, Simon.
http://www.uboatarchive.net/U-570Plate20.htm

I was able to find the Exhaust Air Duct on some drawing on the starboard side of the boat (can not find it in any photo's of U-995 ). This could suggest that valves 'b' are also on the starboard side of the boat.

[SnakeDoc]

Simon,
exhaust air duct is on the port side of the boat. Forward 'b' valve is on the forward bulkhead, on the port side of hatch, near the upper edge of the door (with blue handle). The oxygen manifold is located in the aft starboard corner of engine room - over the clutch piston is visible water trap and manifold itself. Over the hatch to electric motor room are visible two thin lines - I believe they are lines to aft torpedo room and to forward part of the boat. There is also one large pressure gauge - I think it also belongs to this system. I was not able to locate aft 'b' valve.


--
Regards
Maciek

[falo]

Tore you said: "although it is shocking to see what they have done to my old boat". I suppose that I now comprehend what you mean. Please look at the attached pixs. The first shows a double-page, the printed pictures displays the boat during dropping on the two fundaments in the early seventies. If you look at the bow you can recognize the torp doors and the limber holes surrounding them. If you look at my pix (as said before from 2011 or 2012) the bow looks today very basic.

Regards
falo

[tore]

Falo.
Yes , much have been changed and I don`t understand some of the changes, the flood gates are the fingerprints of the submarine. It would not make much of an extra to put in some floodgates, they have blanked off some floodgates instead as shown on your photo. On the other hand they have put up an extra wind deflector on the radar casing which never was there on any VIIC, that cost extra and they have removed the original exhaust outlet and put in a new instead, that cost extra as well. Why if funds are short?
Tore

[NZSnowman]

Simon,
exhaust air duct is on the port side of the boat. Forward 'b' valve is on the forward bulkhead, on the port side of hatch, near the upper edge of the door (with blue handle). The oxygen manifold is located in the aft starboard corner of engine room - over the clutch piston is visible water trap and manifold itself. Over the hatch to electric motor room are visible two thin lines - I believe they are lines to aft torpedo room and to forward part of the boat. There is also one large pressure gauge - I think it also belongs to this system. I was not able to locate aft 'b' valve.


--
Regards
Maciek

Thanks Maciek for the information.

Do you have any photo's of the exhaust air duct and the oxygen manifold, I don't seem to have any photo's of them

The oxygen line look like 10 mm? 

[NZSnowman]

Compartment ventilating and supply systems

I image we should look after the engine room crew

Let take that bad air away

[NZSnowman]

Tore, what is that small hull opening right next to the vent valve, is it a drain line?

http://www.360cities.net/image/submarine-u-995-machine-room#2.39,-64.09,48.4

[tore]

Simon.
Engineroom stand by and ready to get rid of that bad air. . I assume your question concerns the ventilationshaft drain as indicated on the photo below.
Tore

[SnakeDoc]

Hi Simon,


1. Forward 'b' valve.



2. Water trap and control manifold






The manifold itself is the same as in forward torpedo room:

Back to the two lines above the door to aft torpedo room - now I think, that one of them is oxygen supply line to air exhaust duct, second - maybe the line to aft torpdo room or to control room.


--
Regards
Maciek