continued from the other thread...

[CaptnDale]

What is recreational triox?? I'm not familar with that course.

Recreational Triox is one of the names for tri-mix intended for use at relatively shallow depths (shallower than 140 feet).

Personally, I have long struggled with the concept of this course or those like it for two reasons. These courses promote the use of oxygen as a dilutant gas. While this makes some sense in nitrox diving, it makes little sense to increase the percentage of oxygen in a tri-mix when you have helium available. The second problem with this course is that it is usually taught as an entry-level technical course or as a recreational course to students who do not yet have the experience, skill or the discipline to do proper planning and to do well-regulated, controlled decompression ascents. Helium is a very unforgiving gas and a rapid or "saw-tooth" ascent profile can easily lead to serious decompression sickness when the same ascent while breathing air or nitrox would be relatively safe.

[theskull]

Recreational Triox is one of the names for tri-mix intended for use at relatively shallow depths (shallower than 140 feet).

Personally, I have long struggled with the concept of this course or those like it for two reasons. These courses promote the use of oxygen as a dilutant gas. While this makes some sense in nitrox diving, it makes little sense to increase the percentage of oxygen in a tri-mix when you have helium available. The second problem with this course is that it is usually taught as an entry-level technical course or as a recreational course to students who do not yet have the experience, skill or the discipline to do proper planning and to do well-regulated, controlled decompression ascents. Helium is a very unforgiving gas and a rapid or "saw-tooth" ascent profile can easily lead to serious decompression sickness when the same ascent while breathing air or nitrox would be relatively safe.

Very good points! I've also wondered why anyone would bother using helium at depths that shallow from both a cost perspective, and a planning/top-off perspective. Air can be topped off with more air and you're off for another dive. Triox would have to be drained and another fill bought or topped off by someone who can continuous blend, or you end up doing new calculations for deco obligations with your new near-trimix blend after an air top-off.

theskull

[CaptnDale]

I apologize to PPO2 Diver for getting into this discussion here. Perhaps this part of the thread could be moved to another area.

I've also wondered why anyone would bother using helium at depths that shallow

The lack of judgment exhibited by supposedly experienced divers in the depth range of 100 to 130 feet is truly incredible. Last week I had six divers on my boat doing a dive to a wreck at 105 feet. Three of them had rented tanks from me and none of the three tanks came back with more than 100 psi left in them. Two were completely empty. This is only one example of inappropriate behavior which is easy to see and document. Might not narcosis have something to do with this? Would not a little helium in the mix help?

Air can be topped off with more air and you're off for another dive. Triox would have to be drained and another fill bought or topped off by someone who can continuous blend, or you end up doing new calculations for deco obligations with your new near-trimix blend after an air top-off.

For most single tank dives in the 100 to 130 foot range where Triox would be used the diver will breathe the gas down to near 500 psi. At this level it will nearly always make more sense to empty the tank and start over. In the case of diving with doubles where only half or so of the gas is used, you can usually just top with air and get a reasonable breathing mix. Yes, you have to plan the next dive.

My concerns are not with the logistics or the planning of shallow dives with trimix. My concerns are with the skills of the divers who take these beginning technical courses.

I start my students with Decompression Procedures and Advanced Nitrox. All of them are experienced, with at least 100 dives logged and a large percentage of them are recreational instructors but most of them have trouble, in the beginning, holding their decompression stops. I attach Reefpoint Sensus "blackbox" recorders to them and have them do a simulated staged decompression. I then download their profiles. Most believe that they did nice, "stairstep" profiles until they have a look at the printouts and see a sawtooth curve. It takes time and practice to get to the skill level required to make safe trimix dives. I am more comfortable with having my students get an entry level technical course first and then some experience with decompression diving before proceeding to trimix.

I would like to know how those who teach recreational trimix bridge this learning curve with their students. I know that if one were to ask the students, most would say (and truly believe) they are more ready than they are.

[brettbyers]

I think you guys are missing the point of this class, it is not a technical class. It does not deal with decompresion. It does state that it is a recreational class. Does't PADI and all the other training agencies have a deep specialty class? Wouldn't it be safer for the students to be a little less narced when down at these depths? Wasn't nitrox something only tech divers used fifteen years ago? Maybe this is the next step for rec diving. Duane, go ahead and advertise this class and try to make diving safer.

[DeepDiverBob]

I think you guys are missing the point of this class, it is not a technical class. It does not deal with decompresion. It does state that it is a recreational class. Does't PADI and all the other training agencies have a deep specialty class? Wouldn't it be safer for the students to be a little less narced when down at these depths? Wasn't nitrox something only tech divers used fifteen years ago? Maybe this is the next step for rec diving. Duane, go ahead and advertise this class and try to make diving safer.

I think the concern is when dealing with helium, a lot of people dont have the diving discipline to complete safe dives with an unforgiving gas.

[ppo2_diver]

Bob,

Thanks for moving the thread into an appropriate forum.

I've always believed that the deeper people go, the more perfect their skills need to be. If recreational instructors who take Adv Nitrox and Deco courses can't hold stops, then should they pursue this level of diving? If they can't manage their gas supply, they shouldn't be doing dives deeper than 60 ft IMHO.

I think to bridge the learning curve is to hold the students to a higher level of mastery than our standard recreational courses. For the recreational triox classes, students don't start using helium right away. Their skills are evaluated using Nitrox to determine if they are ready for helium or not.

[CaptnDale]

I've always believed that the deeper people go, the more perfect their skills need to be. If recreational instructors who take Adv Nitrox and Deco courses can't hold stops, then should they pursue this level of diving? If they can't manage their gas supply, they shouldn't be doing dives deeper than 60 ft IMHO.

We agree.

I think to bridge the learning curve is to hold the students to a higher level of mastery than our standard recreational courses. The Adv. Nitro and Deco classes I teach, I hold the students to the same performance standards as a trimix class as that will hopefully be their next step in diver education and to make them more proficient technical divers.

Yes, we are on the same page here. The Advanced Nitrox and Decompression Course(s) exist to get divers thinking and acting like technical divers. Once they are at that level they are ready to start using trimix.

For the recreational triox classes, students don't start using helium right away. Their skills are evaluated using Nitrox to determine if they are ready for helium or not

How do you get students who have not yet made a commitment to technical diving ready to dive trimix in a single short course? How do the skills required to dive recreational trimix differ from the skills required to dive technical trimix? Do you think it is just a matter of depth? I believe that the most important thing that seperates technical divers from recreational divers is their philosophical approach to diving. Technical divers think differently about diving. Getting a diver to think like a technical diver may be difficult to do in such a short time, whatever their skill level.

[SLIM]

I for one think that this class even though I can teach IANTD's version is like a way to get more money. If they wish to take a class about being deeper then why not a normoxic class?

We need to look at why we are having classes like these. Most technical diving classes tought to 170 and now in the last few and I do mean few years we are having to add a class inbetwen with a recreational class that deals with He. He is so unforgiving. Is it because divers are trying to go to fast and get certs? Why do we need these classes when just a few years ago we were still doing dives to 170 on air or a light EANx mix and using other gasses to deco out with. Is it the new stuf that we have learened about narcoses? Why do we push such a class?

Remember there are many reasons that make this good but just as many that make it a waist. Are the newer divers moving so fast that they truly do not know what there abilities are and what their capabilites are?

Remember that not all divers will ever think the same or agree on everything. Like a buddy of mine says about SM diving you ask 10 SM divers and you will get 11 answers.

Do I agree with all of the new classes with the high O2 content and He content? Like Skull mentioned a top off can change things so fast. If they are not going ot learn about technical diving and deco, do they need to be down that deep?

Not to slam one way or the other but so many things that one can pnder and think about.

SLIM

[M&P+4]

OK - I don't have a clue about the actual subject matter, but I do have a question....what's unforgiving about helium?

[theskull]

OK - I don't have a clue about the actual subject matter, but I do have a question....what's unforgiving about helium?

It both ongasses and offgasses faster than nitrogen. So an ascent that is a little too fast will result in DCS much more easily than if diving air or Nitrox.

theskull

[theskull]

. . . The lack of judgment exhibited by supposedly experienced divers in the depth range of 100 to 130 feet is truly incredible. . . . Might not narcosis have something to do with this? Would not a little helium in the mix help?



For most single tank dives in the 100 to 130 foot range where Triox would be used the diver will breathe the gas down to near 500 psi. At this level it will nearly always make more sense to empty the tank and start over. In the case of diving with doubles where only half or so of the gas is used, you can usually just top with air and get a reasonable breathing mix. Yes, you have to plan the next dive. . .



I totally agree with the lack of judgment of many "deep" divers. And my opinion is that the problem is with lack of knowledge, training, and respect for consequences -- not with temporary narcosis while they are at max depth.

Single tank dives on Helium mixes with no deco gases and no deco training? Now you really are scaring me. They will think they are diving a deep gas and want to test its limits. And will those who get a top-off on the half-used doubles be carrying a laptop with them to plot their "NDL" for the subsequent dives on their new mix? I doubt it.

I now consider my previously stated objections to Triox as trivial--I truly had no idea it was being promoted as a single-tank recreational gas without appropriate tech training.

theskull