Tores mailbox VIIC and VIIC/41 operation and technical details

[Don Prince]

Hello Mr. Tore,


That's what I was looking for, thank you...  After getting a good 7 hours sleep, my head is much clearer now!


I realize that the water column head pressure from the internal fuel tanks is about the same, and the water column head pressure would be less from FBT 2, R 1, and FBT 4 when in the fuel oil configuration.


I was thinking about fuel tank usage and this is how I perceive it would go:
1. R 1 for better/easier full ballast control when diving or at periscope depth
2. FBT 2 and FBT 4 converted to full ballast control, for better fuel economy (less resistance from a deep hull)
3. The Internal tanks in an alternating method as not to disturb the U-Boat's horizontal balance


What do you think?


Regards,
Don_ 

[tore]

Don.
Within limits I agree. However the way the Germans used the VIICs I don`t think they had so many options. Before leaving for a warpatrol they had to store up as much fuel as possible. As previously stated we very seldom used the MBTs for fuel as our strategy was mostly coastal defense, having access to fuelling stations all along the coast.
Tore

[Don Prince]

Hello Mr. Tore,


I know that the clutch may be disengaged between the e-motor and the propeller drive shaft when charging the batteries.  And I remember that the drive shaft break is applied when charging the batteries with that e-motor.  The only thing I have forgotten is why was the break applied?


Regards
Don_

[tore]

Don.
I don`t believe you had to disengage the tail clutch when charging the batteries as we used to top up the batteries while using the diesel for propulsion. Of course the engineers kept an eye on the load of the engines and adjusting the battery charging within proper limits.
When you are running on one engine the drag cause the other propeller to rotate. In the event that you did`t want the motor/ generator  to rotate you had to apply the break.
Tore

[SnakeDoc]

Hi Gentlemen,

Patent DE470723C Filing date Jun 7, 1925 - Publication date Jan 25, 1929

Standing fluid centrifugal drum with upper supply and removal of the material to be centrifuged by axial pipes

I have found the this patent document (in attachment).

I have also attached two others patents that may bring some light to the solutions developed by Ramesohl & Schmidt A.G., Ölde i. Westfalen.

--
Regards
Maciek

[Don Prince]

Hello Mr. Tore,


I believe a full current charge at 1660 amps they just had the diesel connected to the e-motor as a motor-generator, and the prop was disconnected.


However, I believe your answer is correct about stopping prop spin on a side that is not running... (Thanks!)


Regards,
Don_

[SnakeDoc]

Regarding various scenarios when different elements of the fuel oil/lubricating oil/cooling water systems are out of order (based on German manuals):
Lubricating oil:
normal operation: attached lubricating oil pump forces oil through the lubricating oil distribution box, lubricating oil cooler to the engine.
attached lubricating oil pump out of order: connect together lubricating oil systems of both engines at the distribution box. Connect together both lubricating oil collection tanks.
both attached lubricating oil pumps out of order: force the lubricating oil (by means of the auxiliary lubricating oil pump) from both lubricating oil collection tanks through the distribution box to the engines.
lubricating oil cooler out of order: bypass damaged cooler, both attached lubricating oil pumps force the oil through the working cooler

Cooling water:
normal operation: attached cooling water pumps force the outboard sea water through the distribution box, lubricating oil coolers, engines, blowers to the exhaust manifolds.
attached cooling water out of order: both engines are cooled by one attached cooling water pump.
cooling by auxiliary cool water pump: when both attached cooling water pumps out of order.
cooling down by hand pump: when the engines are shut down after running under high load (i.e. during alarm diving), it is necessary to cool them down by means of the hand pump
circulating the water by hand pump: used to circulate the water with anti-corrosion agent through the cooling water system (outboard sea water intake and outlet have to be shut).

Fuel oil:
taking the fuel oil by means of the external (depot fuel oil) pump: through the fuel oil hose, fuel oil meter and fuel oil transfer system to the fuel oil tanks.
taking the fuel oil by means of the auxiliary lubricating oil: the auxiliary lubricating oil pump can be used as fuel oil transfer pump, pumping the fuel through the fuel oil meter to the fuel tanks.
giving the fuel oil by means of the auxiliary lubricating oil: outboard, from the fuel oil tanks, through the fuel oil meter.
filling the fuel oil tank from the fuel oil tanks: by means of the pressurized cooling water
transferring the fuel oil from main ballast and fuel oil tank to the internal fuel oil tank by means of the auxiliary lubricating oil pump:
transferring the fuel oil from the internal fuel oil tank to  main ballast and fuel oil tank by means of the auxiliary lubricating oil pump:
draining the internal fuel oil tank by means of the trimming pump: the trimming pump can be used to drain the internal fuel oil tank by means of the auxiliary hose connection between the fuel oil compensating system and the pump.
draining the internal fuel oil tank by means of the cooling water hand pump: by means of the auxiliary hose connection between the pump and compensating system
draining the internal fuel oil tank by means of the auxiliary cooling water pump: by means of the auxiliary hose connection between the pump and compensating system


--
Regards
Maciek

[Don Prince]

Great info Maciek...


Hello Mr. Tore,


I found the following in the British U-570 Report... Is this correct?



Circulating Water System
 
   
The circulating water pumps are fitted in pairs at the forward ends of each engine.  They are engine driven from the crankshafts.
 
   
2.  The main inlets are fitted at each side of the starting platform and are in duplicate, the inner valve being a sluice.  There is a common suction to each pair of pumps and there is also a common delivery pipe and a common air vessel.  A relief valve is fitted in each discharge, the water from this relief passing to the bilge.
 
   
3.  A throttle valve is fitted in the suction side in order to regulate the amount of water pumped.


Generally, was the diesel attached water pump replaceable at sea or was it a depot job?
Regards,
Don_

[tore]

Don.
Below is an image of the attached double coolingwater pumps driven from the front side of the crankshaft. As you see the pumps are placed well below the floorplating and are not easy accessible. When we had the broken coolingwater pump, we were able to inspect the collateral damage and change the parts by the engineroom crew.
Tore

[Don Prince]

Hello Mr Tore,


OK, its a double piston pump not actually two water pumps... The word "pairs" confused me!
If one piston or one set on valves fail will the pump still be functional enough to cool the engine?

Don_

[tore]

Don.
I guess it depends on the failure as you have common discharge and no isolating shut off and common gearwheel pto on the crankshaft. I guess the capacity of the pump would be OK, but I would prefer to shut of the damaged pump completely and using other cooling alternatives.
Tore

[Don Prince]

Hi Maciek,

I'm having some problems with the Fuel Oil: Info...

Using the Auxiliary lubricating oil pump to transfer fuel oil from one tank to another?  If you are taking fuel oil from a saddle tank, then the fuel oil goes through the tank selection valve chest then to the fuel oil valve chest and finally to the aux lubrication oil pump...  Now, what path does the auxiliary lubrication pump use to get the fuel oil back to the internal fuel oil tank? It looks like the tank selection valve chest is a one-way street, unless depot refueling where fuel only flows in the opposite direction?

Draining the internal fuel oil tanks? That U-Boat ain't gonna dive?

Regards,
Don_

[tore]

Don.
Pumping fuel from the fuel/ballast saddletanks might be a problem if you use the internal fuel system as a suction system. The reason would be that the deliverypipe, now acting suction pipe, ends on top of the saddletanks to prevent watercontamination. Without a compensating waterpressure the aux fuelpump suctionpipe would end up in the air.  If for some reason you would have to transfer fuel from the saddletanks in fuelconfiguration by the aux.fueltransferpump you would use a hoseconnection possibly via the man hole.
Tore

[SnakeDoc]

Hi Don,

Using the Auxiliary lubricating oil pump to transfer fuel oil from one tank to another?  If you are taking fuel oil from a saddle tank, then the fuel oil goes through the tank selection valve chest then to the fuel oil valve chest and finally to the aux lubrication oil pump...  Now, what path does the auxiliary lubrication pump use to get the fuel oil back to the internal fuel oil tank? It looks like the tank selection valve chest is a one-way street, unless depot refueling where fuel only flows in the opposite direction?

I have to correct myself.

Fuel oil:
[...]transferring the fuel oil from main ballast and fuel oil tank to the internal fuel oil tank by means of the auxiliary lubricating oil pump:
transferring the fuel oil from the internal fuel oil tank to  main ballast and fuel oil tank by means of the auxiliary lubricating oil pump:
[...]

These two lines should look as follows:
transferring the fuel oil from saddle tanks to the internal fuel oil tanks by means of the auxiliary lubricating oil pump: the pump takes the fuel oil from the saddle tanks through the fuel oil transfer system and pumps it through hose connection of the fuel oil valve chest (I guess b1 or b2) to the internal fuel oil tank (I guess the hose connected the fuel oil valve chest and the compensating system of internal fuel oil tanks (drain connections c1). The water would be removed by fuel through the test lines.
transferring the fuel oil from saddle tanks to the internal fuel oil tanks by means of the auxiliary cooling oil pump: the pump is configured to pump the water to the the saddle tanks, the saddle tanks and internal tank is connected by means of the fuel oil transfer system. Shut the cooling water discharge to the internal tank, open the vent lines of the internal tank. The oil is forced from the saddle tanks to the internal tank by means of the pressurized water.

Draining the internal fuel oil tanks? That U-Boat ain't gonna dive?

Why would the U-Boat dive? Draining the water would be the scenario to make the internal tanks empty (i.e. to make inspection).

--
Regards
Maciek

[SnakeDoc]

Pumping fuel from the fuel/ballast saddletanks might be a problem if you use the internal fuel system as a suction system. The reason would be that the deliverypipe, now acting suction pipe, ends on top of the saddletanks to prevent watercontamination. Without a compensating waterpressure the aux fuelpump suctionpipe would end up in the air.  If for some reason you would have to transfer fuel from the saddletanks in fuelconfiguration by the aux.fueltransferpump you would use a hoseconnection possibly via the man hole.

Right. While pumping the fuel from the saddle tanks by means of the fuel oil transfer system (Treibolforderleitung), Germans simultaneously admitted the pressurized water by means of the compensating system.

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Regards
Maciek