IIRC the weight of the generators was a big problem- particularly when the Washington Naval Treaty had to be taken into account. The US tried building turboele

IIRC the weight of the generators was a big problem- particularly when the Washington Naval Treaty had to be taken into account. The US tried building turboelectric submarines twice, but in both cases they were heavier and slower than equivalents powered by geared turbines. Apparently advances in electric motor/generator technology in recent years have reached the point where it's practical again.