83 of 100 leaves you 17% of your hull protection, which tain't much... The US subs were rated lower than the German, but only from an engineering perspective. The U-Boats were tested for crush, and rather conservatively also, but the US boats were not, and the depth was decided by an equation someone had on a piece of paper, so if the paper said the boat could go to 600 feet (roughly 200 meters), then they said you could safely dive to 300 feet (100 meters) and be "safe". Ultra-conservative on diving depth. Crush depth might have been even deeper, and quite a few US boats did go below 600 feet - going by guess-timates, since their depth gauges didn't register deeper than 600. But if you take that 600 foot figure, and multiply it by 17%, you come up with 102 feet... death at 102 feet instead of 600+. Use 1000 feet instead, and that is 170 feet deep for death... That is one aspect of submarine warfare the submariners did not have though - a "gauge" on how much hull structure integrity they have left.
