Training for "Recreational Trimix"?

[waterpirate]

I will not comment on the reputation of instructors at thr T1 or higher, other than to say that they vary as wildly in thier aproach as a OW instructor, with 100x the risk.

Where you are now is the natural progression of a experianced mission driven diver. IMHO you need to seriously look at taking the next step to learn " what you do not know ". evan if you choose not to continue to dive that way.

The choice comes down to risk management. Continue to ride the limits, take the next step, or shallow up your dives. Which ever choice you make you should find a good mentor to help you. Scuba board is good for discussion, but sucks for execution. There are many instructors in south fla. diving big singles on bounce dives to shoot fish. I would find one if I were you.

Personally I can tell you that there is no joy in my life greater than doing 45+ on the hydro before starting back.
Eric

---------- Post added January 11th, 2013 at 03:19 AM ----------

Oh, and contrary to popular belief there are some really goood benefits of carrying and useing a deco gas on ndl dives, specially if you are riding the edge of the limits. Paying a quality instructor to explain those benefits to you would help you to start understanding " all this gas stuff".
Eric

 

[danvolker]

Agree & concur . . .that "pony bottle" should be a slung deco cylinder of Oxygen.

Note: Shallow depth NDL's on Helium can be less than Nitrox, or even Air diving:

The greater diffusivity of Helium from a free phase bubble model perspective (i.e. RGBM) means possibly loading idiopathic bubble seeds/bubble nuclei and having a Boyle expansion pathology resulting in DCS upon ascent --even if you were diving trimix within air or nitrox NDL's. . .

Attached are the comparative NDL's for Eanx 32 and Helitrox; and example deco profiles for bottom times at 30m and 33m, for Ean 32 and Helitrox w/ or w/o O2 deco. . .

As you can see, the NDL's for even a light triox like NAUI-Tec's are less than Eanx32, within the RGBM paradigm. . . Point is you shouldn't dive trimix as "NDL" prescribed to an Air or Nitrox Table --IMHO the "Rule-of-Thumb" should be always do Oxygen deco on a trimix dive, or even at the very least, an O2 deco clean-up on your last dive in a repetitive "NDL" recreational series of trimix dives. . .

Great post!

I should have mentioned that the way George or Bill or I see the pony bottle with O2 is as a slung tank...we absolutely do not believe in "Pony bottles", and have been dead against them for so long, I actually almost assumed this would be inferred with it being my post....
But of course, with Dumpster in this thread, I do need to be clear I was talking about a stage..not a pony, even if it is a 40 cu foot tank, or a 30.

Also....take a real advanced diver, with 10 or 20 years experience, one that has done stops for year, and gets this absolutely.....
How can you imagine that this kind of diver needs to have an entire class just to be able to switch regs and go to an O2 tank at 20 feet? It is ungodly easy, it takes no brains or skills beyond air sharing skills, and because this diver is not a mentally challenged person, they KNOW that they can't breath the O2 stage until they are at 20 feet--just as the tech diver knows this. This kind of knowledge and behavior set does not require a class...Sorry.

As to the buddy separation issue at the Hole in the Wall, this goes to who the buddies are. I did this dive for decades, and NEVER had a current drag me away from my buddy. For this to happen, one buddy would need to go off on their own--20 feet to 50 feet out....or...on high current days, one would have to purposely leave the protection of the wall or rocks or bottom, and put themselves into the full current...if this happened accidentally, they should have had their buddy see this, and the buddy should have launched themselves into the immediate proximity of the one now in the fulll current..and they are together.....and as to the shark issue, only on spearfishing dives will the sharks in that neighborhood become problematic.....DD is probably referring to dives where a hotshot decides to shoot the cobias off the back of a big bullshark, and that stirs up the local tribe with ideas of a teritorial dispute, and Mike Tyson bad intentions

The worst problem I can imagine Guy having, is a bullshark or two posing for him to take pictures of, and Guy not wanting to stop shooting --and this going beyond the agreed on max bottom time duration...another reason for the clear head of helium, versus the poor judgements of deep air at 130 to 150 feet. But then Guy would have Maribe yanking him back to reality, and not letting the bottom time go beyond where it should..because they are a real buddy team, and each is plugged in to the other.

 

[guyharrisonphoto]

Kevrumbo,

Thanks for that great post. That is the actual, real-world information I like to see. It looks like, for the same NDL time we get with 28%, a trimix blend will put us into deco. That is, of course, why I want formal training in addition to mentoring, as it is taking on a whole new set of skills for dive planning and execution.

This will be on my agenda probably this summer.

Thanks everyone for the responses and different points of view. This is a bigger step in training/diving than I had originally thouight.

And, above all, we will be very, very careful as the people who know me already know.

 

[dumpsterDiver]

Also....take a real advanced diver, with 10 or 20 years experience, one that has done stops for year, and gets this absolutely.....
How can you imagine that this kind of diver needs to have an entire class just to be able to switch regs and go to an O2 tank at 20 feet? It is ungodly easy, it takes no brains or skills beyond air sharing skills, and because this diver is not a mentally challenged person, they KNOW that they can't breath the O2 stage until they are at 20 feet--just as the tech diver knows this. This kind of knowledge and behavior set does not require a class...Sorry..

Dan...I see you think that using a deco gas is simple. I agree, it is simple AND dangerous....Since you feel that it is intuitively obvious that no training is required, do you also assume that the diver or a member of the team will have deployed an SMB while doing the drifting, Deco/accelerated safety stop? Or do you feel that maintenance of the stop depth is so trivial that no hard guideline or tethered smb is required for a drifting deco in open water?

Just curious, since again, I have no training..

---------- Post added January 11th, 2013 at 09:36 PM ----------

As to the buddy separation issue at the Hole in the Wall, this goes to who the buddies are. I did this dive for decades, and NEVER had a current drag me away from my buddy. For this to happen, one buddy would need to go off on their own--20 feet to 50 feet out....or...on high current days, one would have to purposely leave the protection of the wall or rocks or bottom, and put themselves into the full current...if this happened accidentally, they should have had their buddy see this, and the buddy should have launched themselves into the immediate proximity of the one now in the fulll current..and they are together.....

The worst problem I can imagine Guy having, is a bullshark or two posing for him to take pictures of,.

Dan: I'm surprised by your comments on buddy separation in a high current (one-way street scenario). The danger is not that one diver gets off the wall and carried away fast by the current. If that should happen, the buddy "simply" needs to swim hard and catch up...May or may not be simple, but doable...I wonder if you remember the dive you and I and George and Bill did there several years ago?


The dangerous scenario is the opposite, the photog. decides to do some macro on a really cool anemone and drops into a crack in the reef (which he must do instantly when spotting it or he will be carried past it). The buddy is 8 feet ahead and a little higher up and is distracted for 10 seconds by 3 bullsharks each weighing more than the diver with her tanks on. In those short 10 seconds, the diver in the water column has now drifted past the stationary diver. Should the stationary diver (upstream) have a serious entanglement (and in worst case a scuba failure)... it will be impossible for the downstream diver to make it back ...

It is an important distinction that I have to drill into my young son's head... on a drift dive in strong current he is to stay pinned to my shoulder OR well ahead of me, but I scream and yell and shout, if he stops without yelling to me and securing my attention and "allows me" to drift by him, leaving him "on his own". upstream and unreachable..

If the dive is traversing open sand with no hand holds to crawl back to him, even a moderate current could be a problem.

This video of he and I spearing in a current in 80-90 last week (first 30 seconds) shows how he can stay ahead of me, but I wave him off the bottom and want him to stay up with me in the drift and not stop on the bottom... especailly when I am pulling the float.

[video=youtube;82CD8nw6R5U]http://www.youtube.com/watch?v=82CD8nw6R5U&feature=share&list=UU1utDku8vJ RJYgBZImLyLJQ[/video]


http://www.youtube.com/watch?v=82CD8nw6R5U&feature=share&list=UU1utDku8vJRJYgBZImLyLJQ

 

[halocline]

There are several dives in our locale in the 100 to 135 foot range that are available to us. I am interested in getting training for trimix diving at these depths to reduce nacrossis. I would also expect this training to include deco theory and basic one-stop decompression dive planning. We are diving big singles 120-130 cf and would carry a 19 cf pony for deco mix. It wouild be trimix diving with never less than 21% O2.

In addition to the many excellent comments you've received already, it might be worthwhile to consider this. The gas mix is not really the issue; it's diving at this depth without redundancy. Sure it can be done, but in the long run it just makes sense if you are going to regularly dive in this depth to invest in doubles and get deco training. Diving with doubles is fun other than lugging them around on land, and although I have zero sidemount experience, it certainly seems to be what all the cool kids are doing these days and there's an obvious advantage in physical top side logistics.

I get the idea that a dive identical to what you are now doing, except done with gas that results in less narcosis, seems to make sense from an enjoyment and safety standpoint. But what you might consider is that single tank recreational dives in the 120-130 ft range could be considered somewhat dicey to begin with, especially on a regular basis.

 

[danvolker]

Dan...I see you think that using a deco gas is simple. I agree, it is simple AND dangerous....Since you feel that it is intuitively obvious that no training is required, do you also assume that the diver or a member of the team will have deployed an SMB while doing the drifting, Deco/accelerated safety stop? Or do you feel that maintenance of the stop depth is so trivial that no hard guideline or tethered smb is required for a drifting deco in open water?

I have never felt the need for a tethered line to the surface for drifting deco--to make it somehow easier--it is just easy, period.....the only reason I can think of for shooting the smb, is so that the boat will know where we are, but beyond that, what is the big deal about watching your depth gauge and holding stop depth????


---------- Post added January 11th, 2013 at 09:36 PM ----------

Dan: I'm surprised by your comments on buddy separation in a high current (one-way street scenario). The danger is not that one diver gets off the wall and carried away fast by the current. If that should happen, the buddy "simply" needs to swim hard and catch up...May or may not be simple, but doable...I wonder if you remember the dive you and I and George and Bill did there several years ago?

Actually, I have no recollection of diving with you, and did so many dives with George and Bill on the Hole in the wall, I really would need you to go into much more detail, if you want me to know what you are talking about.Remember, you are the one that tries so hard to be anonymous, to not use your real name, and refuses to meet people. Maybe if I had the opportunity to have a coffee with you, or even dive with you some time, I might have a CHANCE at knowing who you are, or remembering a dive with you long ago.
I can say that niether Bill nor George nor I ever had any hard to handle separation incidents at the cave....Though back in those days--early to mid 90's, if we were on the cave , I may have been spearfishing, which could have easily meant being on my own for a while.....our strict buddy guidelines were really followed on tech dives, not recreational spearfishing dives.....and I love the Hole in the Wall dive, and the more current, the more fun it is!

The dangerous scenario is the opposite, the photog. decides to do some macro on a really cool anemone and drops into a crack in the reef (which he must do instantly when spotting it or he will be carried past it). The buddy is 8 feet ahead and a little higher up and is distracted for 10 seconds by 3 bullsharks each weighing more than the diver with her tanks on. In those short 10 seconds, the diver in the water column has now drifted past the stationary diver. Should the stationary diver (upstream) have a serious entanglement (and in worst case a scuba failure)... it will be impossible for the downstream diver to make it back ...

See this is the thing....If your buddy is a photographer or videographer, they are not a functional buddy, they are a dependant buddy--a bad thing for just two people on a very challenging dive. Real buddies don't get separated the way you suggest.

If Guy and his wife were doing a major dive like the hole in the wall, until doing it feels consistantly easy for them, I don't think either should have a camera, and even when it is an easy dive, to have a camera should mean a 3rd buddy--two buddies with no cameras, one with.

 

[dumpsterDiver]

Dan: We did a few dives. I was your divemaster.


I don't want to be the dependent buddy. I'm just arguing that personal (independent) redundancy on a dive like this is smart.

As for the drifting deco. you indicate that using a deco bottle is no harder than holding a normal stop. I agree. On the other hand, the consequences of dropping down too deep with 100% oxygen are potentially more serious than when using nitrox or air.... so my (untrained) opinion is that a diver (especailly an untrained one, like myself) would be safer if they had the security of a string from the smb to better prevent unintended depth changes when on deco/safety stop. maybe trained tech divers don't need or want this "security blanket", but I do (or atleast have my buddy holding the smb and I can use him as a hard visual reference (when doing open water drifting deco dives). To be honest it is just more relaxing to "hang" off the string and be a few pounds negative and keep the smb pointing up.

I was curious, it has been a long time since i looked through a tech diving book and didn't know what they recommend as best practice...or if they have any recommendation...

 

[danvolker]

Dan: We did a few dives. I was your divemaster.



I was curious, it has been a long time since i looked through a tech diving book and didn't know what they recommend as best practice...or if they have any recommendation...

Since I was mentored by George, I really could not say what the books would be preaching.....though if I was to guess, since the courses are to make as much money from as many people as possible, they would use the technique best suited to those that are not really proficient yet....
meaning I would expect many teach that the crutch of the smb and hanging on it is fine.... but I think that would be a shame.

We always did deco horizontal, and usually with slight swimming, when off the deep palm beach reefs or free drifting after a deep wreck.... a line to a torpedo float with flag, was fairly typical so the boat could follow us, but we would not hang on it, ever. For one, hanging on it would mean getting vertical, and we wanted the hydrostatic lung loading in the chest, to have maximum blood flow to alveoli, so the lungs would be optimal at filtering any bubbles.

As to the buddy thing.... I was not being preachy....the OP, Guy, is actually a recreational diver with very advanced skills, as is his wife.
They trained hard, and can hold stops with ease, and are an "ideal buddy team"....meaning your same ocean buddy concept of buddy separation, is not relevant to this THREAD.

So when are you going to introduce yourself, and drop the anonymity? Or go diving with Bill and me... again

 

[guyharrisonphoto]

Dan,

That is why I did not even think before clipping the camera off on that first dive. It was obvious to me that it was not the place or time to be distracted. You are also right that I would do more dives before attempting any serious photography and when I did would do so strictly in the open with no chance of getting snagged, and 2 feet from my buddy at most. Dumpster, you are right, no macro shooting on "the hole." I am still a diver first, photographer second and have passed by many photo ops if I felt getting the shot might create a risky separation with my buddy. Even on the shallower reefs, if the current is blowing too hard to swim against, I forget about macro and just stay in the open and off the reef and shoot larger stuff. I do like the luxury of spending a lot of time with a macro subject, and for that I have the BHB or the shallow reefs when the current is light.

Dumpster, Maribi and I have intentionally practiced, for almost every drift including at night, and in all sorts of current, holding the safety stop without the SMB. That being said if using trimix even at "recreational" depths required deco per Kevrumbo's post above, I would deploy the SMB because that makes holding the stop with very high precision even easier.

 

[waterpirate]

I would add this to the discussion of the smb deployment. While it is convenient at times to " hang " on the smb, it is not it's purpose. It is to let the surface know where you are hanging. If you need to hang on the smb, you prolly would benefit from some remedial boyancy training.
Eric