Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Don.
I see you, have mixed up the compensatingsystem with the fuelsounding. There are three ways of measuring the fuelcontent in the bunkertanks. One for the inboardtanks 1i and 2i which Maciek has explained with his drawings. The pipings,containers,valves and cocks can be seen for 1i at the aft bulkhead in the control room and for 2i at the forward bulkhead, pretty much dominating selector cocks (valves). The samples are drained into  rather large containers which used to be removable, today they look like tackwelded into the support and shut by a lid. These containers, which were not marked, and contained fuel, should not be emptied into the bilge but carried and emptied into the measuring container in the engineroom shown on the sketch for the compensating system. After the measuring, the container is drained into the funnel and to the fueloil collector tank. It is hard to see the system on the available photos but I guess you can see the funnels behind some connectionboxes on port and starboard forward engineroom bulkhead.
The saddle fuel/ ballast tanks having checkpipes going almost to the top of the tanks were only checked for compensatingwater at the top and were drained for the F.O.BTKs 2 in the fuel collectingtank in the engineroom and F.O. BTKs 4 in a container in the controlroom.
The third way is that for the F.O. bunker/ regulatingtanks which have sigthglasses next to the sightglasses for the regulatingtanks in the aft end of the controlroom.
Tore

[Don Prince]

Hello Mr. Tore,


I apologize for asking so many dumb questions...  All I had to do was take a pause and think about the plumbing in my home to understand a little more about water pressure in pipes.  This is a different medium for me where I spent 46 years tracing electrical wires to components on a circuit board or schematic.


Now, I don't have a problem with venting, or sounding (measuring).  Thank you for your patients...


One question...  When a mission was completed, how was the fuel oil collecting tank emptied and cleaned out in preparation for the next mission?


Regards,
Don_

[tore]

Don.
Some times it is easy to get confused when different systems are interfearing, I remember ( some 60 odd years back) when I crawled all over the pipes of the VIICs to figure out how the piping worked with limited access to drawings. To know how at that time was a matter of life and death of 46 men. The VIICs have so many alternatives in the piping systems which some times was a challenge to use to its full extent. Emptying the fueloil collecting tank is one of them. It is a suctionpipe from the collectingtank to a system having hoseconnecting to a pump on shore as well as a valve connection to the suction of the handcooling waterpump which at the discharge side has a hoseconnection to wherever you want, see sketch below. As the discharge side of the handpump could end up in the galley or engine coolingwater system required a certain knowledge by the engineroom crew to prevent disaster or a furious cock on you neck.
Tore
 

[Don Prince]

Hello Mr. Tore,


I was wondering why contaminated oil was going to the galley...  Perhaps a chef's salad with a special oil and vinegar dressing???


Regards,
Don_

[tore]

Don.
The coolingwater handpump had many tasks, apart from a possible supply of dirty fueloil to the galley, a more serious task was to pump anticorrosive oil into the sea coolingwater system. As you can see it was a hose connection to the suctionside of the pump were you could connect a hose to a barrel of anticorrosive oil and a discharge via valve D1 to the cooling watersystem (Druckwasser). I am afraid the chef salad was non existent on a VIICs, in that case it would had to be made of seaweed and may be dirty fuel oil did not had to be mixed with vinegar to get the proper dressing for seaweed.
Tore

[VIC20]

Tore or Maciek do you have any data about knots at RPM when driving astern?

[VIC20]

Maciek, I guess this was yours? http://sourceforge.net/apps/trac/derleitendeing/wiki


What have you tried to achieve?

[tore]

Mark.
As far as I remember the GW and I presume MAN were converted into non reversible engines as from 1943. Thus the power for going astern was limited to E-motors. The direct reversible diesels I guess could give the same power astern as forward. The propellers would not give the same thrust astern though. I am sorry I have no figures, may be Maciek have some. Generally submarines were maneuvered by E-motors.
Tore 

[VIC20]

Thanks, I just want to add reversed diesels because it was possible (till 43)… (and subsim players are used to it)

[SnakeDoc]

Hi Mark,

Tore or Maciek do you have any data about knots at RPM when driving astern?

Unfortunately, I do not have any data about astern drive.

Maciek, I guess this was yours? http://sourceforge.net/apps/trac/derleitendeing/wiki


What have you tried to achieve?

Well, yes, I have started this project. In the first iteration I have tried to model U-Boat and its dynamics - especially when submerged. I have created (or rather implemented) algorithms for calculating centres of mass and centroids of the tanks (with any amount of water in them), then I have calculated the centroid and centre of mass of the whole vessel, which resulted in the moment of forces. I have also taken into account the rate of flooding and blowing of the tanks. This is was I have achieved. Finally, I wanted to give the operator the control of the whole vital installations of the boat, allowing him blowing particular tanks, shifting water between trim tanks, controlling compensating tanks and so on. All this would result in the position of the vessel in the water and her movements.
The project has been stalled, as I contacted with Captain Jerry Mason and have involved in the translation work. Now I'm doing wide research in the torpedo fire control systems - when I finish it, maybe I will go back to the derleitendeing - now my knowledge is far greater.

--
Regards
Maciek

[tore]

Maciek and Mark.
You certainly are going into quite a task Maciek and Mark if you are going to incorporate Macieks studies into the game it would be a very demanding play almost like the programmes which are used for training COs and EOs final course before being commissioned. The fruitmachines and similar firecontrol "computers" were very much the first stage of our to days computers without the semiconductor technique. We used rheostats, resistors and capacitors  requiring unbelievable space for a relative simple calculation.
Final question Mark I am just curious, what would you use the astern speed figures for?
Tore

[VIC20]

I need them to make the astern speed in the game more correct. Actually any known astern speed at a given RPM would help me to figure it out for all RPMs. Reversed propellers are totally different (hull in the way, propeller efficiency itself, drag when going backwards etc.) - even a rough guess would help me.


Interesting stuff Maciek, details like this won't make it into the first version of my game but I will try to implement it into the later main version which should be much more complex.

[tore]

Mark.
I believe we only used the astern thrust very shortly in following cases: 1. maneuvering alongside, 2.turning on the spot one propeller ahead, the other astern and for 3.emergency braking, in all cases the speed would be of less importance. In cases of diesel reversing, the timedelay, the time to shift camshaft etc., would probably be a more important factor than acceleration or retardation characteristics. A longer operation of going astern I would assume would not be likely and moreover the thrust bearing is only designed for running continuously ahead. Just a few thoughts on the subject as I can`t fully understand the need for the asternspeed.
Tore 

[Don Prince]

Hello Mr. Tore,


Things seem to be awfully quiet on the site, perhaps we need some more basic (dumb) questions to liven things up...


To start:


When I read about blowing the ballast most times the documentation only refers to Ballast tanks 1 through 5 and the negative buoyancy tanks.  However, there are two tanks that are not mentioned; the stern and bow buoyancy tanks.  I believe these tanks are open at the bottom with slits, and have a vent valve, and a low pressure air line. They are fully equipped do do the job quite well...


It would seem if there were an emergency dive situation that these tanks would get blown besides running all the un-needed crewmen to the bow of the U-Boat???


Please let me know when these tanks are used for something other than Longitudinal stability...


Regards,
Don_

[Don Prince]

Hello again Mr. Tore,


There are 2 lubricating oil tanks with a total capacity of 6.5 m3, and a dirty oil tank with a capacity of 0.79 m3.  Where does all that dirty lubricating oil go, certainly not in the much smaller tank?


Regards,
Don_