I understand what you are saying Juz but there are other methods NOT taught, if you know anyone in the Navy try to get on one of there divers rescue courses. i did one in Portsmouth and the other in Ilfracombe, there is also a course that you can do with the DDRC the REMT is the better one
Here
The problem with people is that they do an O2 admin course and think they need one because there might be two on the boat that need O2 because they are both unconscious but there could be three "SHIT" or FOUR dam were having a bad day !!
do the course you'll find out loads of stuff that PADI, BSAC etc dont teach because they want there ass covered. if you have just done the O2 admin course do this one as well.
As for feeling guilty/or living with yourself afterwards about loosing people because of whatever reason, thats life you can only do so much. In the words of my old CSM "he wont be the first or the last get used to it" if you have done your best what else could you do?
Graham