I've read and read about the German schnorkel, but all that ever gets talked about is the air induction, never the exhaust.

As a former US Navy submarine officer and the Engineer Officer in two boats, my natural instincts have always made me curious as to how things work. Our boats had a rather elaborate snorkel system, but it was the engine exhaust arrangement that made them complex.

The snorkel mast consisted of a 15-inch, two-piece, telescoping, vertical pipe which was forward of a similar but shorter exhaust pipe which was vented such that the exhaust fumes went aft under a deflector plate. The masts were raised and lowered differentially with the snorkel head valve approximately 5 feet above the exhaust when both were raised. The induction mast was dry inasmuch as it had a head valve which was shut automatically whenever the mast was lowered. The exhaust mast was flooded when it was raised and had to be blown dry by the pressure of the exhaust gasses once the engines started.

The snorkel induction mast was connected to the main induction valve, which, of course, was always shut when submerged. Air then passed to the two engine rooms through their normal engine room induction line and valves.

The exhaust was quite another matter. Each engine had two exhaust valves, the hand-cranked inboard valve and the hydraulically-operated outboard valve which would direct the exhaust through a tailpipe and over the side when surfaced. There was an additional snorkel engine exhaust valve which directed each engine's exhaust into the snorkel exhaust line, rather than to the outboard exhaust valve, and on to the main snorkel exhaust valve. This valve opened hydraulically, but not until the exhaust pressure was 17 psi above atmospheric, i.e., sufficient to overcome the pressure of column of seawater in the snorkel exhaust mast and blow the mast dry. It shut automatically when snorkeling was secured.

That was how our systems worked. How did the Germans do it?

Thanks,

Fritz Steiner
LCDR, USN (Ret.)