[DALESDIVER]

Basically what Mark said, is the correct procedure, STAY ON THE HELIUM!

Helium is a freindly gas, it reduces the amount of CO2 produced and off gases cleaner than N2, We have played about with different procedures and the best is Heliox all the way up, including bailout gases of 50/50 and 80/20.

99% of tables that we are using at current time run on the old idea that He is bad for us, so it gives you credit for jumping off it ASAP, the more modern approach, following research by Dr Bill Hamilton is it gets you out of the water quicker on a heliox mix than trimix, his tables for 10/90 have been dived and they get you on the boat while the computer wants to be at 15m...

Looking back to o/c, I used the GUE method and tables and gases, and was always out at least 20-25 minutes before the guys switching back to 32 @40 etc, I always switch to a trimix at deco, keep the N2 as low or lower than in the bottom mix and it works wonders.

As a comarison of gases, on the flying enterprise last year, two of the team dived 10/52 with linked 4th cell, I dived 10/90 linked in, and for the same bottom time I had two minutes different in my deco, but twice as clear a head, and less fatigue after the dive due to a cleaner off gassing due to no N2 in the mix, I dont flush the loop to pure, as its already at 87% on its own at1.4 at 6m, only time I run 100% is if driving manual, or had a very hard dive.