Did they? Knowing the risks, imo, requires more than just being aware of the failure scenarios - it also means having an understanding of the probabilities involved. Playing Russian roulette with 1 vs 5 rounds have the same worse case outcomes, but the odds are very different.

Not doing destructive testing, hiding info from the guy who was supposed to look at the ship, etc. that's avoiding getting a handle on risk.

> None of us would have designed a better submarine

Probably not, but otoh, it sounds like they probably could have done so and failed to take the necessary steps to make it happen.