Rec Trimix

[TheRedHead]

Empirical Long Term Studies are still on going with the US Navy, with regard to the RGBM "Bubble Model" (at least that what Weinke likes to tout for his proprietary algorithm).

We used GAP software in our class which is the same RGBM model.

 

[TSandM]

Redhead, I think you missed my point entirely. You say the average recreational diver doesn't have the skills to manage trimix, and therefore "recreational" trimix is a misnomer. I'm saying that GUE, which recommends trimix in "recreational" depths (80 - 130) TRAINS people to have the skills to manage trimix before training them to use it. The "recreational" in the course name does NOT refer to taking folks who have 20 dives and their AOW and teaching them to dive helium.

Ask lamont what the rec triox class was like . . .

 

[TheRedHead]

Lynne, I think the name could be confusing to some divers. And it is not just GUE who uses that name. I can just see a "Try Trimix" dive like the rebreather intro courses. Not from GUE, of course, but from PADI.

But my point still remains that on many 80-100 ft. dives there is no point in using Trimix. That was the point of this thread.

 

[TSandM]

And I still think it depends on how susceptible to narcosis you are, the complexity of the dive planned (see lamont's discussion of laying line), whether the cost is unduly bothersome, and how much you want to do those particular dives. You get a clear head in trade for having to manage an ascent more carefully. For some people, that might be worth it.

If PADI comes up with a "try trimix" class, I'll be on the bandwagon with you.

 

[TheRedHead]

I think everyone has a depth where they become impaired from narcosis. Mine is 120-140 feet. The easier breathing argument resonates with me at those depths too. That is where I would consider helium. But I don't dive in cold water which I could see adding an additional stressor.

 

[Marlinspike]

I don't think that the difference is that huge- if a diver isn't willing to shave time off and experiment, then they will have to do stick to the dives they know are safe-shorter, shallower dives.

If they are planning on experimenting, hopefully they don't just go from 100' to 450' in one dive. I would hope that they would get the proper training and then gradually test the waters.

Thats ok...I am checking out of this one. This line of logic is all I needed to hear to convince me that some people are irresponsible about pushing limits and posting nonsense on this tread. "Got bent last time, add in a little more deco next time"...way to limit your time diving and on the planet Do It Easy.

~Marlinspike

 

[*Floater*]

I was hesitant to initially quote directly the post on gavin scooter list about He uptake and washout vs. N2, but I found it here re-posted in a forum accessible to everyone. I assume David's summary in the post is fairly accurate since no one posted to correct him in either forum, even though I'm sure there were others on those lists who attended the conference. Of course, the study itself remains unconfirmed until it's published in a peer reviewed journal, but if true then it would explain what the WKPP guys had been observing in their own dives.

And here's some more GI3 from Feb 2002 for those who are interested.

JJ has been using 50/50 for his 70 bottle and 35/25 for his 120 bottle now for a few years. Bill Mee has been using heliox, I have been using nitrox. Bill Mee gets the cleanest results.

We have been trying to see what works best.

JJ and I played sports all our lives, I was a defensive back and JJ was a linebacker at U of Florida. That takes a toll on the knees. JJ found that when he used the 50/50, he had no symptoms of any kind in his knees, when he used nitrox, they felt weird afterwards. My knees do not react to deco at all, so I can not tell by that measure.

Bill Mee found that he was able to speed the deco severely by using all heliox. I just do the same thing over and over as the baseline, so we can see if it is the gas or the deco that is successful or unsuccessful.

The overall changing of the shape of deco and the gas choices were done by myself and JJ through trial and error, and by watching what happened with other team members.

Interestingly, even the most fit guys, like Bill Gavin, would get bent if the used 30-40 oxygen bottles for 110-120 starting depth and then the oxygen, whereas if they used 35, 50 and oxygen they did not get bent, so that is how we got there. JJ and I found that using the trimix in the deeper deco gases improved results massively. JJ and I also found that lowering the oxygen in the bottom gas and boosting the helium made deco a lot faster and cleaner, contrary to what the "theories" tell us.

In general, we found that helium is a wonder gas for solving the deco problem.

 

[lamont]

[...replying to a description i posted of a dive that i use helium on...]
Sorry dude, but to me that sounds like someone making an excuse for doing it wrong. Sounds like the situtation you just described is exactly the reason why people dive doubles and true redundant configuration.

which is why i also dive doubles. i dove a single tank a week or two ago for the first time in 5 months. most of the GUE rec triox class is about dealing with doubles and multiple failures and team responses to failures.

 

[TheRedHead]

And your point is, Floater?

 

[do it easy]

Thanks for posting this Floater. I think that I'm annoying Marlinspike be being so flippant, but what you quoted is a good example of what I meant be experimenting with deco. This can be interpolated and extrapolated to any experience level. Freshly minted OW divers can dive progressively challenging dives to find their comfort level, just as cave divers can push to find where they draw the line. I just finished trimix class, but now, I am "experimenting" to see which tables I like and which ones I don't like. I'm not diving any deeper than than before but maybe I don't need that extra 5 minutes with a more conservative gradient.

And here's some more GI3 from Feb 2002 for those who are interested.