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Sniper297 · 12-02-14, 02:24 PM

"Crush depth for a Porpoise class sub is 250 ft"

Don't get confused between test depth and crush depth. The test depth is the depth that the builder guarantees, and civilian engineers actually dive each new boat down to that depth but no deeper before the Navy accepts delivery. Design depth is 150% of the test depth, and most would go to 200% or better before something failed. Usually that was seals gaskets or valves, in fact the S class had a riveted hull so below 150 feet the water leaked in faster than the pumps could deal with it, so actual crush depth was far below the practical limit. An S class would probably flood completely instead of crushing.

Porpoise was the first US sub with a welded pressure hull, but it still had the problem with the propeller shaft seals and periscope shaft seals leaking heavily under pressure.

12-02-14, 02:24 PM	#8
Sniper297 The Old Man Join Date: Dec 2005 Location: Philadelphia Shipyard Brig Posts: 1,386 Downloads: 160 Uploads: 19	"Crush depth for a Porpoise class sub is 250 ft" Don't get confused between test depth and crush depth. The test depth is the depth that the builder guarantees, and civilian engineers actually dive each new boat down to that depth but no deeper before the Navy accepts delivery. Design depth is 150% of the test depth, and most would go to 200% or better before something failed. Usually that was seals gaskets or valves, in fact the S class had a riveted hull so below 150 feet the water leaked in faster than the pumps could deal with it, so actual crush depth was far below the practical limit. An S class would probably flood completely instead of crushing. Porpoise was the first US sub with a welded pressure hull, but it still had the problem with the propeller shaft seals and periscope shaft seals leaking heavily under pressure.