Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Katuna.

Below I have tried to indicate the details of the wardroom. COs cabin is obvious. The wardroom had two bunks on the starboard side. Towards  the ship side were  the bunks. The lower bunk is for the chief engineer and the upper bunk for no 1. My "office" was the cupboard towards aft, the cupboard contained drawings , logbooks and papers related to my job and I had a small plate fixed to the cupboard wall as a writing desk, towards the wardrom was the blackboard for the acid weight. The typewriter I borrowed from the radio operator as did the CO. The wardobes and lockers were kind of humide and our stripes got green, so quite against the rules I asked the chief electrician to install one of those coalfiber bulbs in my wardrobe closet and lockers to keep it dry. This worked but was exclusively for me, even the CO didn`t get it. I don`t know if other copied my idea. On the port side of the wardroom are the bunks and lockers for the junior officers. As the wardroom was normally used as dining and dayroom, the poor guys used hot bunks. With some minor trouble you could ease down on the lower bunk using same as a seat at the table when somebody slept in the upper bunk.
Tore

[Katuna]

Tore - Is there any tank located under the pumps and piping forward of the engines or is it just open bilge? In the line drawing below it shows a Fuel Oil collection tank spanning from Port to Stbd. On Simon's 3D rendering there is no tank there. I realize that Simon may have purposely left that out to clarify the piping detail. Curious as I'm beginning to move that direction.

[tore]

Katuna. I guess you can trust Simons drawing, I can`t remember any other tank in this area. However the draintank is a part of the fuel venting and draining system of the engines which all ends up in the draintank. This is an intricate system of very small pipes on the engine and I guess more or less impossible to copy on this scale. Nevertheless the system is important as it is designed to prevent fuel pollution of the bilges. Below a small part of the fuel daytank, supply and drainage system, if you want to go into the system just ask.

Tore 

[tore]

Katuna

Another GA plan showing the fueldrain tank.
Tore

[Katuna]

Oddly, the Trumpeter kit actually has that piping. Some of the few pipes they actually molded. This is a pic from another builder but it shows those drains, albeit a little overscale. That's easy enough to recreate in brass wire.

What is the actual purpose of the FO gravity tank?

[Katuna]

Another question, is the pipe in Simon's drawing shown running through the center tanks the same as in the plate drawing?

[tore]

Oddly, the Trumpeter kit actually has that piping. Some of the few pipes they actually molded. This is a pic from another builder but it shows those drains, albeit a little overscale. That's easy enough to recreate in brass wire.

What is the actual purpose of the FO gravity tank?

Katuna

As you probably know the fuelsystem of the VIICs are seawatercompensated which means the fueltanks are always full, having fuel on the top, eleminating the possible trim trouble and free surface effect. As the fuel is consumed the tanks are topped up by the seawatercompensating system which    takes its seawater from the main engine coolingwater at the exhaustsilencer watercooling and pumped up to a head  tank in the towercasing, by that the system is always under the correct pressure. From the head tank the water enter the relevant fueloiltank and fuel on the top of the tank can be transfered to the fuelsystem of the engine. The fuel system on the engine consist of a double day gravetytank (settlingtank) one half connected to the engines at the time. The tank not connected to the engines is topped up by the compensatingsystem, the other half to the engine driven fuelsupplypump attached to the engine. As the system sketch shows a MAN engine having the fuelsupply pump at the aft end I have drawn the supply pipe to the front of the GW engine. The fuelsupply pump supplies fuel under low pressure to the HP fuelpump for each cylinders. The system for suppling fuel to and from the daytank has a meter dial for the consumption and a special cock for easy selection of tanks. Just ask if any question.
Tore

[tore]

Katuna.
I might be I misunderstodd you question on the pipeline you show on the systemsketch plate 9. It shows indeed the main coolingpipe to aft, compressores, Emotors, Thrustbearing etc. But the pipe you refer to is probably the main bilge drainpipe which goes to the suction side of the main bilge pump in the controlroom, thus two different pipes. See image below.
Tore

[Katuna]

Ok, I didn't notice the bilge pick up screen was attached to that pipe. Does that bilge pipe run the length of the boat? I believe the bilge pump is in the Control room, correct?

[tore]

Katuna.
Yes the main bilgedrain pipesystem goes to every compartment in the boat. You are able to open the footvalve of the adjacent compartment by extended valvestem/rods through the watertight bulkhead as shown below.
Tore

[Katuna]

Thanks for the bilge info.


Ok, next question, what is this shield that is outboard of both engines? Depending on which drawing you look at, it either angles down or it had a compound curve that angles back upwards. Is this some sort of sheetmetal shield or bracing? Looking at the drawings it is difficult to decipher what it is exactly.


In Simon's drawing it is clearer from overhead but it isn't clear which direction it goes or what material it is made from. To me it looks like it curves down from the engine bed rail to the frame ribs.

[tore]

Katuna.

I assume you refer to the two black rectangles between the frames towards bord and the engine. Below is Simons drawing of the dieselair system. As the dieselengines are fairly large they need a lot of air for combustion. This air would create a substansial draft through the submarines compartments hence you need a separate diesel air supply shaft outside the pressurehull as drawn by Simon. Although the dieselair shaft main inlet valve is situated in the tower casing, the intake is susceptible to water during heavy sea and the airduct gets partly filled with seawater. Just after the main intake hullvalve for the dieselair ( in the engineroom) the circular air duct is split in two, and transferred into rectangular sheet metal ducts, port and starboard, which fits between the frames towards the pressurehull , the ducts ends up halfway from the bilges. Hence the seawater ends into the bilge and the mainengine air intakes are safely from the water. During heavy weather it was fascinating to see how much water was gushing into the bilge where it could be handled by the bilge pump in the controlroom.
Tore 

[Katuna]

This is the plate I'm speaking of. It appears to go under the starting air tank and over the oxygen tank.


I was unaware there was a duct from the Induction valve to the intakes.

[tore]

Katuna.
What you refer to is the mainengine foundation steelbed in the engineroom which is a very thick steelplate where the mainengine is adjusted and fixed by bolts and nuts. The foundation has of course to be very stable and rigidly connected to the hull. Simons drawing shows the top bedplate which has to be accurately placed for correct adjustment of the mainengine bedplate. The foundation plate is slightly elevated and outside the engine contact surface bended and tapered down to the frames where it is fixed by welding for an extra rigid and stable connection to the hull. See image below.
Tore

[Katuna]

Ok, that's what I thought but could never verify with a clear end view.


I see now the air intake duct. So if I understand correctly, the duct ran below that stabilizing plate and the plate acted as a diffuser or baffle to allow sea water to drop out into the bilge and air was pulled up into the intake through the spacings in the plate?


Then this would be the induction duct, correct?