WW2 German vs US submarines drive questions

[tifosi12]

AFAIK the German subs run either under Diesel power or electric power, meaning the Diesel motors directly drove the props and when they run electric, it was the electric motor that drove the props.

I recently learned that the GATO class design was different: Here the Diesel generators were solely used to charge the batteries and the boat run on the electric motors exclusively.

Assuming I got my facts right, is there an advantage to either system?

Also I was wondering they call it a direct drive on the German subs, meaning the Diesel engines directly drive the shafts and props withou gear in between. If that's the case how can they switch to the electric motors? Am I missing here something?

I figured some of you on here have the answers. Thanks.

[DrSchmidt]

The Gato design, that today is used also on German boats, has the advantage, that the generators can be perfectly matched to the Diesels and the drive motors perfectly matched to the props. This provides overall better electric efficiency at the cost of weight and space.

[tifosi12]

The Gato design, that today is used also on German boats, has the advantage, that the generators can be perfectly matched to the Diesels and the drive motors perfectly matched to the props. This provides overall better electric efficiency at the cost of weight and space.

Interesting, thanks much!