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Re: Deck vent for Stern Driving Tank
Posted by:
Don Prince
()
Date: January 23, 2009 01:40AM
Hi Simon,
The square vent grill is for the stern dive tank #1, and the round vent grill is for the Bow dive tank #1. The high point of Dive Tank #1 id very clode to thr square deck vent. I cut some text that was published in the Subcommittee Report Journal (SCR) that I did several years ago.
German U-Boat Type VIIC: The Ballast System
[Personal Research and Observations by Don Prince]
The Type VIIC ballast system employed a fairly complicated combination of tanks. There are 12 different tanks shown in my diagram below. All of these tanks play an integral part in the U-boats’ ability to dive and maintain a level attitude. First, I will list each tank and its functionality.
D1 – Dive Tank #1 [Tauchzelle 1] - This tank is located at the stern of the U-boat and is external to the pressure hull. It has two outlet valves located on the top of the tank. The one furthest to the stern is visible at deck level. The second outlet valve is located further forward and is covered by the metal decking. Its location is to the Starboard side. The deck above it has a door with a square shaped vented grate to allow for air to escape. On the lower section of the tank there is an inlet valve to allow the tank to be flooded with sea water. The capacity of D1 is approximately 32.0 cubic meters.
B1 – Balance/Trim Tank #1- This tank is located within the pressure hull near/below the stern torpedo tube. The function of this tank is to maintain a level attitude when the U-boat is submerged. The capacity of this tank is relatively small, approximately 3.60 cubic meters.
T1 – Torpedo Compensation Tank #1 – This tank is located within the pressure hull. When a torpedo from the stern tube is launched, there is an immediate loss of weight in the stern section of the U-boat. Therefore, this tank will take on water to help maintain the level attitude of the U-boat.
D2 – Dive Tank #2 [Tauchbunker 2] - This tank is located external to the pressure hull and in the stern section of both saddle tanks. When the U-boat is to dive, the upper bleed valves open to allow the air to escape, and the lower tide valves open and allow the sea water to enter the tanks. Each section has a capacity of approximately 12.25 cubic meters. Therefore, the total capacity for dive tank #2 is 24.5 cubic meters.
R1 – Compensating Fuel Bunker #1 [Regelbunker] - This tank is located external to the pressure hull and in the center section of the saddle tanks, and its construction is very unique. The tank has an opening at the very bottom to allow sea water to enter the tank as the fuel was being used. The fuel is lighter than sea water, so the fuel tends to float to the top of the tank. This is where the term self compensating comes into play because nothing needs to be pumped into this tank to offset the depleted fuel weight. This tank increased the U-boats’ fuel capacity by approximately 20 cubic meters on each side. Therefore, the total capacity of R1 is 40 cubic meters, or approximately 43.2 tons of fuel which extends the U-boats range about 2000 nautical miles. This modification started with the Type VIIB.
R2 – Compensating Water Tank #2 [Regelzelle] – This tank is located external to the pressure hull in the center section of the saddle tanks. This tank has a dual purpose. When the weather was severe, this tank was partially flooded to provide a degree of lateral stability to help prevent roll. The primary purpose was to compensate for the U-boats’ weight loss. During a long voyage, the weight of the food stuffs, munitions, and fuel in the internal bunkers within the pressure hull were depleted. Sea water was pumped into R2 to compensate for this weight loss and maintained the U-boats trim and waterline.
N1 – Negative Bouyancy Tank #1 [Untertriebzelle] – This tank is located external to the pressure hull in the center section of the saddle tanks. This tank was added to the Type VIIC to enable improved diving time in combat by remaining partially flooded. The minimum dive time for the Type VIIC was 30 seconds.
D4 – Dive Tank #4 [Tauchbunker 4] - Exactly the same functionality as Dive Tank #2, a mirror copy at the bow and external to the pressure hull. When the U-boat is to dive, the upper bleed valves open to allow the air to escape, and the lower tide valves open and allow the sea water to enter the tanks. Each section has a capacity of approximately 12.25 cubic meters. Therefore, the total capacity for dive tank #4 is 24.5 cubic meters.
T2 – Torpedo Compensation Tanks #2 – There are two tanks, port and starboard, internal to the pressure hull in the bow section. This is different from T1 at the stern. There is only one torpedo tube at the stern and it is centered along the longitudinal line of the U-boat. During a combat engagement, only one torpedo is launched from the stern. However, the bow section has four torpedo tubes; two side by side. If, for example, only one torpedo from the starboard side was launched, then the starboard trim tank would take on water to keep everything in balance. The same process is followed when the other torpedoes are launched.
B2 – Balance/Trim Tank #2 - This tank is located internal to the pressure hull near/below the bow torpedo tubes. The function of this tank is to maintain a level attitude when the U-boat is submerged. The capacity of this tank is relatively small, approximately 3.55 cubic meters.
D5 – Dive Tank #5 [Tauchzelle 5] - This tank is located at the bow of the U-boat and external to the pressure hull. It has one outlet valves located on the top of the tank. The outlet valve is under the metal bow decking on the Starboard side. The deck above it has a round vented grate to allow for air to escape. On the lower section of the tank there is an inlet valve to allow the tank to be flooded with sea water. The capacity of D5 is approximately 32.0 cubic meters.
Now, we have covered all the various tanks; with the exception of the Main Ballast Tank D3. This tank is located within the pressure hull and is a bit more complicated in design and functionality. The Main Ballast Tank is located directly below the control room.
I hope this helps...
Regards,
Don_
"A man's got to know his limitations..."
Harry Callahan, SFPD
The square vent grill is for the stern dive tank #1, and the round vent grill is for the Bow dive tank #1. The high point of Dive Tank #1 id very clode to thr square deck vent. I cut some text that was published in the Subcommittee Report Journal (SCR) that I did several years ago.
German U-Boat Type VIIC: The Ballast System
[Personal Research and Observations by Don Prince]
The Type VIIC ballast system employed a fairly complicated combination of tanks. There are 12 different tanks shown in my diagram below. All of these tanks play an integral part in the U-boats’ ability to dive and maintain a level attitude. First, I will list each tank and its functionality.
D1 – Dive Tank #1 [Tauchzelle 1] - This tank is located at the stern of the U-boat and is external to the pressure hull. It has two outlet valves located on the top of the tank. The one furthest to the stern is visible at deck level. The second outlet valve is located further forward and is covered by the metal decking. Its location is to the Starboard side. The deck above it has a door with a square shaped vented grate to allow for air to escape. On the lower section of the tank there is an inlet valve to allow the tank to be flooded with sea water. The capacity of D1 is approximately 32.0 cubic meters.
B1 – Balance/Trim Tank #1- This tank is located within the pressure hull near/below the stern torpedo tube. The function of this tank is to maintain a level attitude when the U-boat is submerged. The capacity of this tank is relatively small, approximately 3.60 cubic meters.
T1 – Torpedo Compensation Tank #1 – This tank is located within the pressure hull. When a torpedo from the stern tube is launched, there is an immediate loss of weight in the stern section of the U-boat. Therefore, this tank will take on water to help maintain the level attitude of the U-boat.
D2 – Dive Tank #2 [Tauchbunker 2] - This tank is located external to the pressure hull and in the stern section of both saddle tanks. When the U-boat is to dive, the upper bleed valves open to allow the air to escape, and the lower tide valves open and allow the sea water to enter the tanks. Each section has a capacity of approximately 12.25 cubic meters. Therefore, the total capacity for dive tank #2 is 24.5 cubic meters.
R1 – Compensating Fuel Bunker #1 [Regelbunker] - This tank is located external to the pressure hull and in the center section of the saddle tanks, and its construction is very unique. The tank has an opening at the very bottom to allow sea water to enter the tank as the fuel was being used. The fuel is lighter than sea water, so the fuel tends to float to the top of the tank. This is where the term self compensating comes into play because nothing needs to be pumped into this tank to offset the depleted fuel weight. This tank increased the U-boats’ fuel capacity by approximately 20 cubic meters on each side. Therefore, the total capacity of R1 is 40 cubic meters, or approximately 43.2 tons of fuel which extends the U-boats range about 2000 nautical miles. This modification started with the Type VIIB.
R2 – Compensating Water Tank #2 [Regelzelle] – This tank is located external to the pressure hull in the center section of the saddle tanks. This tank has a dual purpose. When the weather was severe, this tank was partially flooded to provide a degree of lateral stability to help prevent roll. The primary purpose was to compensate for the U-boats’ weight loss. During a long voyage, the weight of the food stuffs, munitions, and fuel in the internal bunkers within the pressure hull were depleted. Sea water was pumped into R2 to compensate for this weight loss and maintained the U-boats trim and waterline.
N1 – Negative Bouyancy Tank #1 [Untertriebzelle] – This tank is located external to the pressure hull in the center section of the saddle tanks. This tank was added to the Type VIIC to enable improved diving time in combat by remaining partially flooded. The minimum dive time for the Type VIIC was 30 seconds.
D4 – Dive Tank #4 [Tauchbunker 4] - Exactly the same functionality as Dive Tank #2, a mirror copy at the bow and external to the pressure hull. When the U-boat is to dive, the upper bleed valves open to allow the air to escape, and the lower tide valves open and allow the sea water to enter the tanks. Each section has a capacity of approximately 12.25 cubic meters. Therefore, the total capacity for dive tank #4 is 24.5 cubic meters.
T2 – Torpedo Compensation Tanks #2 – There are two tanks, port and starboard, internal to the pressure hull in the bow section. This is different from T1 at the stern. There is only one torpedo tube at the stern and it is centered along the longitudinal line of the U-boat. During a combat engagement, only one torpedo is launched from the stern. However, the bow section has four torpedo tubes; two side by side. If, for example, only one torpedo from the starboard side was launched, then the starboard trim tank would take on water to keep everything in balance. The same process is followed when the other torpedoes are launched.
B2 – Balance/Trim Tank #2 - This tank is located internal to the pressure hull near/below the bow torpedo tubes. The function of this tank is to maintain a level attitude when the U-boat is submerged. The capacity of this tank is relatively small, approximately 3.55 cubic meters.
D5 – Dive Tank #5 [Tauchzelle 5] - This tank is located at the bow of the U-boat and external to the pressure hull. It has one outlet valves located on the top of the tank. The outlet valve is under the metal bow decking on the Starboard side. The deck above it has a round vented grate to allow for air to escape. On the lower section of the tank there is an inlet valve to allow the tank to be flooded with sea water. The capacity of D5 is approximately 32.0 cubic meters.
Now, we have covered all the various tanks; with the exception of the Main Ballast Tank D3. This tank is located within the pressure hull and is a bit more complicated in design and functionality. The Main Ballast Tank is located directly below the control room.
I hope this helps...
Regards,
Don_
"A man's got to know his limitations..."
Harry Callahan, SFPD
