Tores mailbox VIIC and VIIC/41 operation and technical details

[NZSnowman]

In the area of this ventpipe  the max. height between the casing deck and pressurehull is, I guess, 0,70 m. If you compare the vent pipepipe drawing for fwd. ballastanks port and stb. plate 28 with the drawn frame hight app 15 cm, you would end up with a pipediameter of approximately 250 max 300mm, easily fitted under the casing deck and probably not too far away from the biggest pipe shown on the wreck.

I just checked my drawing, I went for 275 mm 

[NZSnowman]

Hi Tore

Just letting you know that were will be no new drawings for the next few days. I am taking a break from drawing and catch-up on some other work.

Simon.

Fueloil compensating valves fuel oil saddle tanks.
The upper drawing you are showing is the system outside the pressurehull and I don`t believe the valves are operated from inside the pressurehull. The fuel/ballast saddletank 2 and 4 starboard and port are just made of light steel sheets and do not withstand any large pressure. They are equipped both as full fueloil bunkertanks and  full ballast tanks with all the connections required. The encircled valves have two positions either in direct connection with the head/buffertank in the tower or in contact with the sea via a small compensatingbox in the bottom of the tank. As fueltank the first position shall be used to ensure the compensating head is allways positive but not exceeding the differential pressure (the height difference between the headtank in the tower and the fueltank). Eg. irrelevant of the ambient pressure regardless the diving depth. 
Tore

Tore, that dimension do you think this pipe would be? I was thinking about 75 mm.

Simon.
To me 75 mm diameter seems to be on the large side. I don`t think it would be any bigger than the fuelpipe from the tanks entering the engineroom as seen on the picture below previously displaid.
Tore

I just checked dive video of U-352 and U-1021, and I found no evidence of this pipe. I think after 60 years at the bottom of the sea all evidence is gone

[tore]

Simon.
Ventpipediameter.
I guess your choice of diameter is pretty much correct.
Tore

[tore]

Simon
Seawater compensating pipes.

Hi Tore

Just letting you know that were will be no new drawings for the next few days. I am taking a break from drawing and catch-up on some other work.

Simon.

Fueloil compensating valves fuel oil saddle tanks.
The upper drawing you are showing is the system outside the pressurehull and I don`t believe the valves are operated from inside the pressurehull. The fuel/ballast saddletank 2 and 4 starboard and port are just made of light steel sheets and do not withstand any large pressure. They are equipped both as full fueloil bunkertanks and  full ballast tanks with all the connections required. The encircled valves have two positions either in direct connection with the head/buffertank in the tower or in contact with the sea via a small compensatingbox in the bottom of the tank. As fueltank the first position shall be used to ensure the compensating head is allways positive but not exceeding the differential pressure (the height difference between the headtank in the tower and the fueltank). Eg. irrelevant of the ambient pressure regardless the diving depth. 
Tore

Tore, that dimension do you think this pipe would be? I was thinking about 75 mm.

Simon.
To me 75 mm diameter seems to be on the large side. I don`t think it would be any bigger than the fuelpipe from the tanks entering the engineroom as seen on the picture below previously displaid.
Tore

I just checked dive video of U-352 and U-1021, and I found no evidence of this pipe. I think after 60 years at the bottom of the sea all evidence is gone

Simon.
60 years at the bottom of the sea takes its toll I can assure you, it`s 59 years since I came on board the U 995 and quite a bit has changed both to me and the U 995 even at the surface.
I have studied the diameter of the pipe once more and reconsidered my guesswork.  I believe your estimate of 75mm is not too far away, may be a fraction smaller but I should think you could go for it.
Tore

[SnakeDoc]

Hi Gents


Few days ago, on 1st December, it has been 60 years ago, when U995 entered into the service as KNM Kaura.


--
Regards
Maciek

[tore]

Maciek
You are absolutely right, unbelievable it is 60 years since she was commissioned as KNM Kaura, but the date was December 6Th 1952. I embarked May 1953. She was our first and only VIIC/41 the two others were VIIC U 926 KNM Kya and VIIC U 1202 KNM Kinn.
Tore

[NZSnowman]

Fuel oil compensating system

Tore,

• How often would you need to open/close the

[NZSnowman]

Simon
Seawater compensating pipes.

Hi Tore

Just letting you know that were will be no new drawings for the next few days. I am taking a break from drawing and catch-up on some other work.

Simon.

Fueloil compensating valves fuel oil saddle tanks.
The upper drawing you are showing is the system outside the pressurehull and I don`t believe the valves are operated from inside the pressurehull. The fuel/ballast saddletank 2 and 4 starboard and port are just made of light steel sheets and do not withstand any large pressure. They are equipped both as full fueloil bunkertanks and  full ballast tanks with all the connections required. The encircled valves have two positions either in direct connection with the head/buffertank in the tower or in contact with the sea via a small compensatingbox in the bottom of the tank. As fueltank the first position shall be used to ensure the compensating head is allways positive but not exceeding the differential pressure (the height difference between the headtank in the tower and the fueltank). Eg. irrelevant of the ambient pressure regardless the diving depth. 
Tore

Tore, that dimension do you think this pipe would be? I was thinking about 75 mm.

Simon.
To me 75 mm diameter seems to be on the large side. I don`t think it would be any bigger than the fuelpipe from the tanks entering the engineroom as seen on the picture below previously displaid.
Tore

I just checked dive video of U-352 and U-1021, and I found no evidence of this pipe. I think after 60 years at the bottom of the sea all evidence is gone

Simon.
60 years at the bottom of the sea takes its toll I can assure you, it`s 59 years since I came on board the U 995 and quite a bit has changed both to me and the U 995 even at the surface.
I have studied the diameter of the pipe once more and reconsidered my guesswork.  I believe your estimate of 75mm is not too far away, may be a fraction smaller but I should think you could go for it.
Tore

I have decided to go for 60 mm.

[tore]

Simon
I guess that`s not far from the correct dimension.
Tore

[tore]

Simon
Fuel compensating saddle ballasttanks
The valve b is a valve only in use when you select the mode you want to use the saddletanks,as fuel tanks or ballasttanks. It is a double seated valve with only two positions  either in direct contact with the head tank in the conningtower when the saddletank is used as fueltank or in direct contact with the sea when the saddletank is used as ballasttank. I believe it is controlled from outside the pressurehull under the casingdeck as it is not often used. I think it is a hatch in the deck for access.
Tore

[NZSnowman]

Simon
Fuel compensating saddle ballasttanks
The valve b is a valve only in use when you select the mode you want to use the saddletanks,as fuel tanks or ballasttanks. It is a double seated valve with only two positions  either in direct contact with the head tank in the conningtower when the saddletank is used as fueltank or in direct contact with the sea when the saddletank is used as ballasttank. I believe it is controlled from outside the pressurehull under the casingdeck as it is not often used. I think it is a hatch in the deck for access.
Tore

Thanks Tore.

I have checked all my photo's and checked dive videos and found no evidence of these pipes. So this morning I started checking deck hatches and I think I can location the positions they enter the saddle tanks using the hatches. I will use this as my glide for the drawing.

Do you think the open end to the sea would have a pipe screen over the end to stop sea weeds etc entering the system?

[tore]

Simon
Sea connection for compensatingpipe.
I don`t believe there is much of a screen. This connection is not for transport of any seawater (throughflow) it is merely a seapressure equalizer connection. The Kingstons take care of the filling of the tank. I`ll see if I can figure out something better tommorrow.
Tore

[NZSnowman]

Simon
Sea connection for compensatingpipe.
I don`t believe there is much of a screen. This connection is not for transport of any seawater (throughflow) it is merely a seapressure equalizer connection. The Kingstons take care of the filling of the tank. I`ll see if I can figure out something better tommorrow.
Tore

Thanks, Tore.

I imagine if the opening is only for equalizing this open could be a lot small than the 60 mm pipe.

[tore]

Simon.
Saddle fuel/ballasttanks
I have not been able to find any drawing or picture of this arrangement. I have looked for a seawater connection but there is non. My conclusion would be, when used as ballasttanks the Kingstons are open and the tank is in direct contact with the sea. Thus when the compensatingpipe is shut to the compensatingtank
( headtank) the pipe is in contact with the seawater via the Kingstons.
Tore

[NZSnowman]

Simon
Fuel compensating saddle ballasttanks
The valve b is a valve only in use when you select the mode you want to use the saddletanks,as fuel tanks or ballasttanks. It is a double seated valve with only two positions  either in direct contact with the head tank in the conningtower when the saddletank is used as fueltank or in direct contact with the sea when the saddletank is used as ballasttank. I believe it is controlled from outside the pressurehull under the casingdeck as it is not often used. I think it is a hatch in the deck for access.
Tore

Thanks Tore.

I have checked all my photo's and checked dive videos and found no evidence of these pipes. So this morning I started checking deck hatches and I think I can location the positions they enter the saddle tanks using the hatches. I will use this as my glide for the drawing.

Do you think the open end to the sea would have a pipe screen over the end to stop sea weeds etc entering the system?

I think I may have an explanation why I can not found any evidence of these pipes. I previous imagine those pipes would run just above the pressure hull, but now I believe there is not enough room, so the Germans run those pipes just under the wooden deck. As both the decking of U-352 and U-1021 are gone, this is why I can not found these pipes in the dive videos.