One of the most important aspects of a deep simulator is the ability to override the automation of certain systems and have full control over all settings. In a U-boat, the power-plant is arguably the most important system; it moves the boat, and charges (or discharges) batteries, blows ballast tanks when surfaced etc.. . Without the power-plant, the U-boat is useless.

In order to simulate an accurate and fun system, I have pulled specs from the VIIC manual. The main powerplant layout includes two banks of motors, engines, 2 clutches, and the propeller itself.


The diesel motors are connected via a clutch to the electric motors. When connected, the electric motors are either run in free spin mode, charge up batteries by using the spin from the diesels, or act as a support/buffer – adding power to the diesel output, or entering charge /braking mode when the diesel over rev due to being out of the water in rough seas. The electric motors themselves can be connected or disconnected, via a clutch, to the prop.

Here is a proper breakdown, from the manual, of the different operations supported:

The diesel engines provide a maximum surface speed of about 18 knots and both E-motors provide a submerged speed of 8 knots. The different working modes are listed below:

  1. Diesel engine only drive
  2. E motors only drive
  3. Support and buffer mode
  4. Diesel-electric drive
  5. Charging mode

Diesel engine only drive
In diesel engine only drive; both diesel engines drive the propellers via the diesel engine couplings, E motors, main couplings, thrust shafts and the propeller shafts.
In this arrangement the E motors are just a part of the drive train and the armatures are unpowered. The fan blowers of the E motors rotate slowly powered by voltage generated due to the remanent magnetism of the unpowered rotating armature.

Electric motors only
With E motor drive only, the diesel engine coupling is un-clutched. The E motors are powered by the battery and work as motors driving the propellers via the main couplings, thrust shafts and the propeller shafts.

Support and buffer mode
In support mode, the output power of the diesel engines is increased by switching on the E motors additionally. Each diesel engine via the diesel engine coupling and in addition each E motor acting as a motor drives the propeller. The buffer mode is used in rough seas. The diesel engines drive the ship’s propellers as in “Diesel engine only drive”. The E motor voltage is adjusted such that with normal conditions the loading and discharge current are equal to zero. If the screw runs above the surface, thus causing unintentional reduction of load on the diesel engine, the E motor works as a generator preventing an inadmissible increase in diesel RPM.

Diesel-electric drive
Diesel-electric drive allows driving both propellers even if one diesel engine has failed. The operational diesel engine works directly driving the propeller on its side. The E motor whose armature would normally run idle, works as a generator delivering power to the other ship side. The E motor on the other side drives the propeller; the diesel engine clutch is disengaged. The current from the primary E motor can either be switched in such a way that it only drives the secondary E motor or an additional light charge of the batteries takes place.

Charging operation.
Charging operations can be differentiated as follows:

  1. Charging with a disengaged propeller shaft
  2. Charging while running on the surface with diesel engines

When charging with a disengaged propeller shaft, the diesel engine drives the E motor via the diesel engine clutch. The E motor runs as a generator and charges the storage batteries. When charging while on the surface with the diesel engines; the diesel engine power drives the propeller. At a constant number of revolutions from the diesel engine, the E motor charges the batteries. In this case, the diesel engine must provide power for the propeller and for charging.




Currently I have implemented a test panel in the simulator to enable the engagement/disengagement of the different clutches (just click the click icon between the power-plants). You can run the power-plants in any of the aforementioned modes independently. You can even have one electric motor go full reverse while the other diesel on the other shaft is running in full forward mode!


Update: 5/26/2016

The UI panel has received a little polish. The look/feel is more a blueprint style now, which I think should work well going forward.




I welcome all suggestions on art direction, functionality, etc…

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