Standard depths for situations?

[Liszt_]

Could someone please provide some information on standard depths for certain situations?

Periscope depth, snorkel depth (manual makes reference to this. wtf is it?), average cruise depth to avoid detection? etc etc etc.

regards,
liszt

[Sailor Steve]

Standardized depths were used for fleet boats. Periscope depth was (I think) 65 feet. Snorkel and radar depths were also standardized, so the captain didn't have to remember himself, just give the order.