Why is it so hard to understand the point of a "safety factor"???
A "safety factor" is used to provide SAFETY under normal conditions. In war, you donŽt have "normal" conditions, so youŽll push it to the limit in an emergency - what else could you do?
If you take a ride in a rollercoaster, youŽll rely on a safety factor for weight. If itŽs built for 20 people you can count on it that it had been tested with much more weight. The decrapancy between normal operation and tested (or calculated) operation is expressed in a safety factor.
If you want a NORMAL OPERATIONAL depth of, say, 100m, would you build a hull that will collapse at 110m? Probably not. But maybe you feel "safer" if you know all parts are able to endure the pressure youŽll find at 250m (which means they can take more than twice the pressure they will encounter under "normal" conditions).
The US Navy thought 1.5 was enough, which simply means that normal operational depth was closer to critical depth compared to German subs. Taking this into account, youŽll probably not try to dive two times deeper than operational depth in SH4, while you CAN do this in SH3. It is pretty obvious that Captains only dived deep to avoid depth charges or detection, it wasnŽt fun. I talked to a U-Boat veteran and he told me that sometimes they dived so deep that the hull bended inside and "you could take a shower" in the engine rooms.
Cheers, AS