Guess who's a newbie TRIMIX diver?!? (and sorta Lake Travis report of 8/13)

[wedivebc]

Why 80%?

If I need the gas volume and my baby booster takes forever to fill an al80 I will blend 80% since with most deco software I have seen there is very little difference in 80-100% as far as washout is concerned. That way I can get a good 3000psi fill when my O2 cylinders only hold 2400psi.

 

[FIXXERVI6]

If I need the gas volume and my baby booster takes forever to fill an al80 I will blend 80% since with most deco software I have seen there is very little difference in 80-100% as far as washout is concerned. That way I can get a good 3000psi fill when my O2 cylinders only hold 2400psi.

I know why some people dive it, just wondered why he dove it.

I guess if your gonna fill your two gas requirement anything will do but was wondering if he had any speical reason for it.

For the record I'm not a GI3 clone just seriously want to know, but I am a 100% kind of man because of the diving I do.

 

[Teknadv3x]

I am a 100% kind of man because of the diving I do.

Me Too

 

[battles2a5]

I know why some people dive it, just wondered why he dove it.

I guess if your gonna fill your two gas requirement anything will do but was wondering if he had any speical reason for it.

For the record I'm not a GI3 clone just seriously want to know, but I am a 100% kind of man because of the diving I do.

My shallow gas of preference is definitely 100% but 80% has its uses, especially in keeping your O2 clock in check. For example, a 200ft dive on 18/45 for 25 minutes, using 50 and 100 for deco will put you at 61%. Substitute 80% for the 100%, and your clock in down to 35% and you will get out of the water only 1 min later (using VPM-B, nominal conservatism). If you are doing multiple dives a day, using 80% can be a good tool to manage CNS loading. Then again, losing the shallow gas altogether will only take a few minutes longer to get out and you have one less bottle to worry about at intermediate depths. I think GI3's "baker's dozen" of reasons not to use the "stroke mix" has driven a lot of people away from 80, but I think anyone with an agenda could come of up a million reasons not to dive any gas out there.

Daylon, congrats on the course. Put some more He in that mix and you will REALLY see the difference. I did most of my training dives w/ 16/24 and while I noticed a difference it wasn't until I started putting the END around 100 when I "saw the light". Have fun w/ it!

 

[Daylonious]

Well, just my take on on but we decided on 80% rather than 100% due to the safety margin. If you're doing gas switches with 100% and you have ANY kind of a swell, you can bob from 17-18 feet to below 20' (which would put you past PPo2 1.6)

80% you have more of a cushion - that's all. Just a safety thing - unless my math is wrong 1.4 to 1.6 on 80% is something like 24 - 34 feet - nice cushion. 1.4-1.6 on 100% is like 13.5 to 20 - and below 20' bad things happen.

And we didn't NEED the the two deco gases for the dive, just needed to demonstrate the skills doing multiple gas switches at depth. In our case we switched to 50% at 60 feet, and 80% at 30 feet.

Anyhoo, glad I got through it, and would love some REAL trimix diving somewhere with decent viz.. i.e. the Oriskany perhaps?

Although adding $100 to every dive isn't really making my wallet feel any better.... ;-)

D.

 

[FIXXERVI6]

you shouldn't be bobbing in lake travis, and passing 20' on o2 isn't an instant death sentance.

but to each their own, when I'm on dive vacations o2 boosters and high pressure banks are abound, nothing like a AL40 with 3100 psi handed back to you slightly warm... mm warm fuzzy o2.

 

[Daylonious]

Well, a lot of things "shouldn't" happen while diving but it IS windy point, and there was a bit of a chop on the lake and we WERE bobbing. I'm only saying that because we were, and I was there, and I was bobbing.

As for the 20' line - hey, if you're comfortable breathing 100% under 20' be my guest, but don't expect me to follow suit.

D.

you shouldn't be bobbing in lake travis, and passing 20' on o2 isn't an instant death sentance.

but to each their own, when I'm on dive vacations o2 boosters and high pressure banks are abound, nothing like a AL40 with 3100 psi handed back to you slightly warm... mm warm fuzzy o2.

 

[ScubaTexan]

Congratulations, Daylon!

 

[battles2a5]

but to each their own, when I'm on dive vacations o2 boosters and high pressure banks are abound, nothing like a AL40 with 3100 psi handed back to you slightly warm... mm warm fuzzy o2.

And then leaving it in the back of your truck for a couple of hours to bake I saw 3400 on my O2 bottle at Ginnie last weekend. Major pucker effect when I charged that bottle before the dive :11:

 

[ianr33]

Congratulations! Having some He makes a huge difference for me in Travis below 130. Much less paranoia!

Now for the nitpicking (this is Scubaboard after all!)

80% makes no sense to me in Travis. A 40 of 100% will last for several dives and is really easy to blend

108's and a wetsuit? What was the plan for a wing failure? Crawl up the silt slope on hands and knees?