Mistakes can,and do,happen aboard military vessels----personally, having served in the Royal Navy for some years, I am AMAZED that there have been no catastrophes, or even major incidents,involving nuclear-powered submarines ,since their introduction into service.Well, not as far as I have been permitted to know about, anyway !! On the other hand, I feel certain that the same cannot be said for the Russians, or indeed ( as far as we know !! ) our American cousins ! A trifling 5 million pounds worth of damage to HMS Trafalgar is a small price to offset against an otherwise enviable safety record----in fact, since the whole point of obscuring some navigational data from the aspiring submarine commanders was to test their resourcefulness and abilities, the exercise can be viewed as a total SUCCESS! ( it's a "British Thing", you see ),as it highlighted their shortcomings in that capacity. So, you see, it was a GOOD THING, after all !!
                              As to the use of "Class A" drugs on ships --- I just don't understand it !! What are these TWATS doing in the Royal Navy in the first place ?? Bring back flogging (and The Tot ), I say !!