My usual final stop deco mix is.....

[Andy Phillips]

Got to say, that really is a bit worrying, you look at your guage and think "thats OK, I've got 100 Bar left" as you do this you breath in, and you think "no I haven't".

Next time I am at 100M, I want more gas, got me 15's now, yipee.

Andrew

[Fathoms Down]

Originally Posted by [b

Quote[/b] (Mark Chase @ Feb. 27 2004,22:50)]IMHO the first option is the best as Extended Range is bsicly a deep air course which is out of date.

I'd agree with you there. IMHO diving to 55m on air is asking for trouble and should only really be considered if you have a desperate need for completing an objective at that depth and can't do it trimix for some reason.

I remember seeing "Adventures to the bottom of the sea" on BBC 2 a while back and it had a guy that went to 84m (ish) in air to try and recover a crate which he thought contained gold. He was very lucky he didn't suffer O2 convulsions but seemed genuinely supprised that he lost the use of his hands whilst down there.

No comment....

[Mark Powell]

Originally Posted by [b

Quote[/b] (Mark Chase @ Feb. 27 2004,22:50)]100m is TDI full trimix. The normal rout is:

Advanced Nitrox
Deco procedures
Entry Level Trimix
Advanced Trimix

I tend to use either 50% or 80% depending on the circumstances.

I agree with Mark C's comments on the steps to take.

My advice would be to take it slowly and build up your experience. TDI Advanced Nitrox and Deco procedures as a combined course is the best starting point.

After this build on your skills and get confident in to 20-40m range. Then once you have mastered all of these skills move on to Entry trimix to take you past 40m. This is a big step up in terms of depth and skills. Full trimix is a further big step.

[jlwarlow]

<font color='#008080'>I'm a lowly swamp gas diver, not Nitrox trained yet but plan to before July for my 40m+ diving holiday

[Rob Evans]

Swamp gas eh? &nbsp;Never knew you could compress methane to 232 bar. &nbsp;I don't care what the decompression advantages may or not be, I'm not breathing the bastard
Only taking the P by the way, no offense intended

[Fathoms Down]

Originally Posted by [b

Quote[/b] (Rob Evans @ Feb. 29 2004,20:27)]Swamp gas eh?  Never knew you could compress methane to 232 bar.  I don't care what the decompression advantages may or not be, I'm not breathing the bastard

Me neither.... although it has been tried:

http://www.techdiver.ws/exotic_gases.shtml

Personally I feel sorry for the poor guy who field tested Radon as a mix gas &nbsp;

[Digger]

<font color='#000080'>OK, so if O2 is narcotic, which I accept it is, does that mean at deeper stops on high O2 (ie 50% at 22m) I could be more narked than at bottom depth? Or is it going to be very similar narcosis levels? I've not really done the reading on this, any suggestions? Is it possible, if I was diving the optimal mix at depth?

[Digger]

<font color='#000080'>Wouldn't it be better for off-gassing if we used 50/50 heliox instead of 50% nitrox then, too? And cut nitrogen out of the equation? Cost we can leave out as a factor here. If helium is a lighter gas we absorb and get rid of faster, won't this work?

[wreckweasel]

ooooh digsboy, that almost smacks of serious diving

O2 Narcs, I've never bought this one myself. All the data I saw seemed to show it was narcotic at 2bar PO2 and above...

As for using 50/50 for deco. I wouldnt!

Cutting your deco mix with *some* helium is ok, but only if your bottom mix was helium rich. IE try to avoid isobaric counterdiffusion!

[bang-on]

Originally Posted by [b

Quote[/b] (Digger @ Mar. 08 2004,12:37)]Wouldn't it be better for off-gassing if we used 50/50 heliox instead of 50% nitrox then, too? And cut nitrogen out of the equation? Cost we can leave out as a factor here. If helium is a lighter gas we absorb and get rid of faster, won't this work?

<font color='#0000FF'>digger,
the main problem with helium at deco depths is the extra time added to decompression.your best option is to reduce helium as you come shallower and replace that gradually with o2 and nitrogen at depths that the n2 will not be a problem with narcs
or cause a major change in % of gases.
helium is great for a clear head at depth but has no advantage over n2 when shallow and a major factor is the cost of the helium and the run time.
cheers
barrie