just to add more fuel to the fire, I was skimming through the online version of "The Fleet Type Submarine"
http://www.maritime.org/fleetsub/index.htm
In chapter 18A dealing with diving, it states:
Quote:
Three types of dives are possible: 1) the quick dive, 2) the running dive, and 3) the stationary dive, the choice being dictated by existing conditions. In all dives the ship is placed in the condition of neutral or negative buoyancy; the use of negative buoyancy shortens the diving time. A quick dive is made when the ship is underway on one or more main engines. The bow planers are placed on FULL DIVE and the forward speed results in a maximum downward thrust on the bow planes. As the submarine submerges, the upper surfaces of the hull and superstructure act as planing surfaces and increase the downward thrust. The quick dive is the fastest of the three types and is used in acceptance trials of new submarines, when it must be executed within 60 seconds from standard diving trim.
|
This seems to imply that the US Navy standard was for the dive to be completed in 60 seconds. Certainly, a crew testing to achieve the quickest time could possibly dive in 30 seconds, but if a boat is surprised and does an emergency dive, 30 seconds from the dive order to periscope depth seems a little tight.