Greetings List,

Someone out there should be able to handle this question easily.

I understand that the saddle tanks on U-Boats were open to the sea, so that as the fuel (I assume it was a marine diesel or a bunker fuel) was used up, sea water would replace it in the tanks. Correct?

A couple of questions come to mind: Notwithstanding that diesel fuel generally has a lower specific gravity than water and will therefore tend to stay on top, I reckon that a U-boat under combat conditions would end up with an oily emulsion of sea water and diesel fuel in the saddle tanks; especially after a good pasting with some well-placed depth charges. Furthermore, they must have had some serious water-separators on board to handle this mess. Am I off base here?

Can anyone provide me with an explanation of how this system worked?

Cheers,

Robert