I certainly don't want to question the quality of the work without more knowledge, but there is certainly little room for error with regard to submarines.
The Kursk, Thresher, Scorpion and a host of others over decades clearly shows the almost unimaginably difficult conditions these vessels operate under.
I can only feel heart break for the families of those lost. Without wanting to sound callous, let's hope it was quick.
"Irreverence is the champion of liberty and its only sure defense."