Sudden switch of diesel to electric engine when dive

[matrixmod]

Especially when you dive, main engine(diesel) switched to electric, engine compartment animation just freeze instead of slowly stopping. It looks jarring.
It only happens when dive. Weird enough, when you just stop the rig, it actually slowly stopping.

[9erRed]

Well in reality when you turn off the diesel to a small motor it makes a "cug" and stops.

But the large motors for the subs did take 3 or more steps to turn them off "safely".
- reduce rpm, turn fuel down, open cylinder tops, decouple prop drive mains, close main air vent to sail. (big red wheel at ceiling.)
There is a large flywheel connected to these motors, so also required braking for that.
- Some steps can be eliminated for emergency changes.
- Some steps also had automated controls for ease of starting and shutdown.

- The electric motors also take 3 or 4 steps to have them "running".

So, there should be a bit of "flurry" of activity happening when an engine type change is called for. And personnel moving between motor types.

Up to 3 or 4 persons for the 2 Diesel and at least 2 for the electric controls.

[DECAFBAD]

Machine room procedure to switch during diving:
1) Disengage the Diesel clutch.
1) Cut the fuel by lifting the fuel handle up to 0°, disengage the supercharger if it was on. The engine is now off, there are no additional steps.
1) Begin closing the intake and exhaust hull valves.

There is no order in these steps, they are executed simultaneously.
The engine keeps pumping air into the exhaust manifold as it spins down, which is normal.

2) As soon as the Diesel clutch is pulled, engage the switches on the main switchboard to the fastest setting. You can see the procedure in Das Boot, it takes less than 2 seconds.
From a standstill the motors spin the propellers to 200RPM in 2 seconds. If underway this is even faster since the propeller doesn't stop turning.

Originally posted by 9erRed:

There is a large flywheel connected to these motors, so also required braking for that.

On the free end, it's a surprisingly light torsional vibration damper, tuned to absorb vibrations at the driveline resonant speed, just to avoid having a barred speed range. The engine was designed to only ever run with the 3 ton electric motor armature clutched in: it was the flywheel.