[Mark Chase]

OK Having just planned three dives with over 100% CNS I can tell you a couple of things.

First the dive plan and the dive are not the same thing. Dive plan gave 100+ cns actual dive cleared deco at 87% day one 82% day two. That was two dives of 65+m with 40min bottom time and 90-100min deco on PP of up to 1.6.

So any one saying they are doing 125% profiles off of tables might not actualy be doing 125% profiles.

My VR3 constantly monitors PP02 at all variable presures throughought the dive rather than just taking the planned deepest profile and doing it on that. Thats where I got the comparison.

Most CNS incidents are wrong as switch events where people switch to 80 -100 % at 30m rather than to travel gas. Unless you are into big profiles with high 02 off gassing it is not going to be an issue. I supose a 40% dive on nitrox to 30M fro 1.0 will show up a few problems but there are not many people planning that sort of profile.

How common is a CNS hit??

One member of my dive club toxed due to an incorect gas switch and bit the end of his toung off when he convulsed. His buddy sent him to the surface missing loads of stops but his PP02 was so high he wasn't bent??

He was back in the water two weeks later ??

Freind of a one of my Dive contacts was the chap who toxed sank and died earlier this year.

Thats two in the last twelve months so it dose happen. There are no set figures for who will and who wont surfice as to say that wen reaching limits of 100% CNS you should not be exerting your self in any way and should have some contingancy. IE a necklesed rig that straps the reg into your mouth, a full face mask, Clipping your self to a lift bag or suitable SMB and SUPPORT DIVERS

ATB

Mark Chase