Hello Gerard,

The manual for the Type VIIC U-Boat Data:


-----------RPM---------sm/h*---------sm/h
==============================
KF---------180----------7.2-----------7.0
LF---------275---------10.2----------10.0
HF---------340---------12.4----------12.0
2xHF-------396---------14.6----------14.0
GF---------435---------16.3----------16.0
AK---------471---------17.7----------17.5
3xAK-------480---------18.1----------17.9

Note* sm/h = sea knotical miles/hour

I believe 3 x AK (Full) Auxilary Mode is full speed on the Diesel and full drive of the E-Motor on the same drive shaft. This should not be done because you are draining the batteries while running on the surface. You will be in dire trouble if you must dive the U-Boat with low batteries!



d) E Auxiliary Control and Buffer Control.

With the E-machine support mode, the performance of the diesel engines is increased by switching on the E-machines additionally. Each diesel engine works via the diesel engine coupling and in addition each E-machine acts as a motor on the screw. The buffer mode is used in rough seas. The diesel engines work like diesel engine drive only in driving the ship screw. The E-machine voltage is such that with normal conditions the loading and discharge amperage are equal to zero. If the screw runs above the surface thus creating an unintentional increase of the diesel engine’s RPM, the E-machine works as a generator and thereby avoids a rise of speed by the diesel engines, thus an unintentional discharge by the diesel engines.

Regards,
Don_

"A man's got to know his limitations..."
Harry Callahan, SFPD