Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Simon.
Looks fine. May be it is time to put in some spice in in the spaghetti. You love for details require venting of the exhaust manifold cooling bends,foldable handle for the starting air handwheel and the manometer for the supercharger pressure. Sorry for my bungling on your nice drawing.

Tore

[tore]

Off the topic.
Surfacing.
I have mentioned before the normal way of surfacing, nicely take the boat up by hydroplanes to periscope depth, the quick sweep with the periscope before blowing all the ballasttanks until semisurfaced in a horizontal position and then blowing the tanks by diesel engine exhaust or in case of RN U class submarine by electric blower.
It happens howewer you have to make emergency surfacing, blowing you ballasttanks at great depth with an incredible amount of HP air. Then you accelerate towards the surface and in case of using the hydroplanes and E-motors as well you might end up braking the surface like the picture below, which I found in one of my Norwegian submarine pamphlets. The picture is presumably taken of a Norwegian U class surfacing in a Norwegian fjord. I guess more for show off rather than necessity. I guess the surfacing angle would be close to 45 degrees exceeding the spilloff limit for the battery acid , spectacular but not to be recommended.
Tore

[NZSnowman]

Tore, a few more pipes...

[tore]

Simon.
I am back with a few remarks tomorrow as I am checking a few pipedetails which seems to take more time than I anticipated. It is primarily the connection to the transmissionflange cooling which needs some attention.
Tore

[NZSnowman]

No worrys, I am off to the big city today to do some shopping, so no u-boat drawing today.

[NZSnowman]

Tore, one thing, how did the cooling water get outside the pressure hull through the hull flange?

If you were looking into the flange at the top, would you see the inner collar for the cooling water, if so how wide is it?

[tore]

Simon
The group exhausthousing don`t have a flange going through the coolingspace, it is simply a ringflange intergrated with the outer surface of the housing without obstructing the cooling waterflow out of the pressurehull. You want see the coolingwater space at all it is entirely closed like a cooling waterspace for a cast iron car engineblock.

Tore

[tore]

Simon
I guess you see the transmissionring small flange at the exhaust manifold side on the shipyard drawing top view and the groupexhaust housing on the sideview the difference between the two migth give you an estimate for the coolingwater dimension.
Tore

[NZSnowman]

Something like this?

[tore]

Simon
Yes.
Tore

[tore]

Simon.
It got to be only one flange in contact with the pressure hull and it looks like the flange is fixed from the inside, the housing is then free to (heat) expand outwards.

Tore

[tore]

Simon.
Group exhaust valve coolingwater pipes.
To make an understandable drawing of this system is not easy, so when keeping an eye on the confusing drawing below I`ll try to give an explanation:
making use of the systemdrawing and copy the system would not work so basis for the described system is photos and common engineering sense.
The main coolingwater outlet from the dieselengine is close to where the manifold endflange joins the transition piece flange. The pipe goes down to the main coolingwater valve at the aft bulkhead, to the short pipe between the main cooling watervalve and the main seavalve and then via the main seavalve to the group exhaust valve and  overboard.
Immediately after the exhaust manifold it is a small pipe branch off which take some of the coolingwater to the lower part of the transition flange, the water leaves the same flange at the outlet on the top. Then the water goes to the lower inlet of the endflange and leaves same at the outlet on the top. It goes down and join the short pipe between the main coolingwater valve and the main sea ( overboard) valve. On the short pipe between the two mainvalves is a branch off to a two way cock, this cock can be put in drain position leading  the system to a funnel and bilge or to the other position connecting the system the the other engine system.
The main drain pipe (yellow)and valve is obvious and ends together with other drains in a funnel to the bilge.
Allthough not shown on one of the engines, there should be a manometer connection to the main drain of the group exhaust valve, that drain comes from the space between the group exhaustvalve and mufflervalve which might have a severe leakage and full seapressure in the space.
The system is based on interpretation of photos and some basic musts but in the end an assumption from me.
Tore

[NZSnowman]

Tore, a few more pipes and tweaking of alignments

[tore]

Simon.
It is beginning to look like the real thing.
I am a bit in doubt of the location of the valve and pipe assembly at the aft bulkhead. I know you recently relocated the supercharger. With a less professional way I used that as a reference. On the shipyard drawing topview it looks like the centerline of the main coolingwater outlet matches the centerline of the outboard supercharger shaft. On your drawing the centerline of the pipe is a bit offset to the inboard. I again bungled with you drawing and put the coolingwater outlet as on the shipyard drawing see drawing below. With reference to the photos I placed the main cooling water pipe  straight down to the main coolingwater valve realizing it created some distance to the  valve inboard.
Tore

[tore]

Simon.
The coolingwater branch off.
My assumption is founded on the photo below and the orthodox way of cooling waterflow, in at the lowest point out at the highest
Tore