Backing off from technical diving

[Diver0001]

I had a very interesting conversation with a friend yesterday. He was telling me about a recent trip he did, where he did a bunch of wreck diving, all at technical depths. He had had the interesting insight that the diving, although it was actually quite good, just didn't light his fire, especially not enough to justify the horrendous cost of the gases to do it.

I told him I really haven't had the urge to do any tech diving for the last year or so. The things I love most just don't require it, and the sites we have where there is interesting critter finding to do at depth are boat dives, that I don't get to very often.

Both of us agreed that we will probably not do much tech diving in the future, and both of us are considering selling some gear.

I wondered how many other people are out there who got the training, did some dives, and decided it just wasn't worth the effort or the expense.

(BTW, I will keep a set of doubles and a deco bottle, just in case, and also because I need to stay current on skills for cave diving, which I emphatically intend to continue to do!)

I'll add my voice to that too. My problem is probably more practical because I'm only really interested in technical nitrox to get longer bottom times on wrecks we dive and all of my tech buddies have all gone the deep/rebreather/cave route. It leaves me in a constant state of having to "grow my own" as my buddies "out grow" me and I'm tired of it. I still make quite a few dives over the NDL's but most of it is so tame that you could hardly call it "technical". I'd say a 5-10 min shallow hang is really all we do these days. It feels more like an extended safety stop than a deco stop even if it is required. In terms of what I'm willing to tolerate, a 10 min hang is ok, if it's 20 min I'm reaching the threshold of boredom and if it's 30 min I wonder why I bothered.

A friend of mine regularly pays a fortune for 2 hour dives with 15 min on the bottom. He's making dives that look impressive on paper but you'd seriously need to use a cow-prod to get me to do that.

R..

 

[waterpirate]

Being eligible to begin tech training is one thing. To be eligible to step into the middle of the program and get into the advanced level classes without going through the earlier classes is another. Try going to GUE and telling them that you want to take Cave 2 because you had a friend teach you everything that is in Cave 1.

To be more specific in the case I described above, I went to a TDI instructor and said that I had the rough equivalent of their regular normoxic trimix class through another agency. I wanted advanced trimix. Fortunately, I had completed TDI Intro to Tech, Advanced Nitrox, and Decompression Procedures long ago. On that basis, I was accepted into the normoxic trimix class, which I finished quickly, and then went on to advanced trimix. There would have been problems if I had not had those earlier classes.

I think GUE would be the last place to play that card. lol My mileage was very different from yours. I think it is still up to the individual instructor to either sign your card or not regardless of previous cards. It boils down to the skills you show up with, even for normoxic.
Eric

 

[Rhone Man]

In terms of what I'm willing to tolerate, a 10 min hang is ok, if it's 20 min I'm reaching the threshold of boredom and if it's 30 min I wonder why I bothered.

I always have a little difficulty with this argument. If I am going out on a charter, even a really short one, you can spend an hour getting to the site, half an hour gearing up, two hour surface interval, hour heading back to the dock - and all that excludes the drive to and from the dock or (in some cases) the flight half way around the world. Given all that non-deco time that gets spent to allow you to have your bottom time, I can't really see why I would quibble over 10 minutes more or less looking at fishes at the end of a dive.

 

[Diver0001]

I always have a little difficulty with this argument. If I am going out on a charter, even a really short one, you can spend an hour getting to the site, half an hour gearing up, two hour surface interval, hour heading back to the dock - and all that excludes the drive to and from the dock or (in some cases) the flight half way around the world. Given all that non-deco time that gets spent to allow you to have your bottom time, I can't really see why I would quibble over 10 minutes more or less looking at fishes at the end of a dive.

I guess it's context. In our local diving you might spend 50 min on the bottom and then another 35 or so ascending in a green bubble with no reference points whatsoever and nothing to see but your own hands.

If we had fishes to look at I might feel differently.

R..

 

[Slamfire]

There's absolutely no way any algorithm in the world knows that you have "1 minute and 16 seconds of no-deco time left".

I'm not exactly sure I understand what you are trying to convey. As it is written right now, I have to disagree. Now, if you meant that no algorithm in the world will be able to reflect exactly what happens to your body in any given day, then I agree with you.

Algorithms are just mathematical models that try to approximate what happens to your body. They will never be 100% accurate with what really happens to your body. But they are certainly capable of telling you to the second when you are about to break the NDL according to the mathematical model. They just won't be able to tell you when you are about to break a cellular wall in your body.

Talking about pushing the limits I know an instructor who would literally ride her computer at the NDL. She would hit the limit at one depth go up a few feet run that limit out go up again ect. until she surfaced. This Instructor had also been bent at least on time before.

This is another reason why some basic deco knowledge (even with caveat that they are not supposed to do deco dives) would be healthy to OW divers. I keep trying to explain friends that it is possible to have an NDL dive be more likely to yield DCS than a decompression dive. The lady in Claymore's example (let's call her Bonnie) could have a higher nitrogen loading at the end of the dive than another diver (let's call him Clyde) that did go into deco, but executed a very conservative ascent keeping below the deco ceiling and padding the last stop.

The way many OW's are currently taught, they think that Bonnie is at a lower risk than Clyde. Clyde is doing "technical diving" -- that MUST mean that his risk level once he reached surface is higher than Bonnie's. Reality is that Bonnie would probably be better served extending her dive time by going into deco and doing a conservative decompression schedule instead of riding the NDL limits every 5 ft all the way to the top.
- But she's not supposed to do that because she's not deco trained.
- Fine, but at least she now has the knowledge to make a more clear, comparative risk assessment.
- But if she goes beyond the NDL she won't be able to pop up at the surface at any time.
- Well, you should not just "pop up" at the surface at any time, even during NDL dives. It is not healthy. Even the most lenient agencies teach you about the benefits of a simple 3 minute safety stop at 15 ft. They teach you that you increase your risk if you don't do it.

 

[boulderjohn]

The way many OW's are currently taught, they think that Bonnie is at a lower risk than Clyde. Clyde is doing "technical diving" -- that MUST mean that his risk level once he reached surface is higher than Bonnie's. Reality is that Bonnie would probably be better served extending her dive time by going into deco and doing a conservative decompression schedule instead of riding the NDL limits every 5 ft all the way to the top.
- But she's not supposed to do that because she's not deco trained.
- Fine, but at least she now has the knowledge to make a more clear, comparative risk assessment.
- But if she goes beyond the NDL she won't be able to pop up at the surface at any time.
- Well, you should not just "pop up" at the surface at any time, even during NDL dives. It is not healthy. Even the most lenient agencies teach you about the benefits of a simple 3 minute safety stop at 15 ft. They teach you that you increase your risk if you don't do it.

I don't understand this, and I am coming from the way OWs are taught. If the diver is diving a table near NDLs (and I know that is not your example), then the diver is told a safety stop is mandatory. If the diver is using a computer, then the current PADI computer course instructions are even more adamant about the use of safety stops. That is the current state of OW training.

So in one of your scenarios, the diver rides the computer to the surface and does a safety stop. If she has an emergency, she should be ale to go to the surface immediately without consequence, because a safety stop is really just what the name implies.

In the other scenario, the diver goes into deco, and the computer signals a mandatory decompression stop. Now what happens if the diver has an emergency and goes to the surface? The diver has a much greater probability of sustaining a DCS hit.

Can you explain why the second scenario is better than the first?

 

[MXGratefulDiver]

What happens if the diver doesn't understand what his computer is telling him? Had that happen once ... dive buddy practically bolted from 120 fsw to 10 fsw because he thought his computer was telling him he had to go there. He was completely ignorant of the concept of "ceiling" ...

... Bob (Grateful Diver)

 

[boulderjohn]

What happens if the diver doesn't understand what his computer is telling him? Had that happen once ... dive buddy practically bolted from 120 fsw to 10 fsw because he thought his computer was telling him he had to go there. He was completely ignorant of the concept of "ceiling" ...

This is part of the training in a modern computer-based OW course. Students are taught that a computer will guide them to decompression stops if the diver accidentally gets into that situation. There is a simulator that can give a generic example of this. They are taught that they need to make sure they understand how their specific computer model does this. The student should leave the course understanding this concept.

 

[Slamfire]

I don't understand this, and I am coming from the way OWs are taught. If the diver is diving a table near NDLs (and I know that is not your example), then the diver is told a safety stop is mandatory. If the diver is using a computer, then the current PADI computer course instructions are even more adamant about the use of safety stops. That is the current state of OW training.

So in one of your scenarios, the diver rides the computer to the surface and does a safety stop. If she has an emergency, she should be ale to go to the surface immediately without consequence, because a safety stop is really just what the name implies.

In the other scenario, the diver goes into deco, and the computer signals a mandatory decompression stop. Now what happens if the diver has an emergency and goes to the surface? The diver has a much greater probability of sustaining a DCS hit.

Can you explain why the second scenario is better than the first?

No emergencies in the scenarios. Never mentioned an emergency. Both Bonnie and Clyde completed their dive and have just arrived at the surface and neither of them broke their computer rules. In that particular moment, Bonnie could well be on pressure group "x", or gradient factor 90, whereas Clyde came up at pressure group "p" or gradient factor 70.

In other words, once a dive is completed, the more inert gas loading someone has, the more likely he/she will experience DCS. It is possible for an NDL diver to come up with more nitrogen loading than a diver that did go beyond NDL. It all depends on their ascent behavior.

---------- Post added August 21st, 2013 at 03:46 PM ----------

But it's a good thing you mentioned emergencies. Going to the surface is always an option as long as you don't have a hard overhead. Better bent than drowned. At least as long as you don't bolt up too fast lest you cause arterial gas embolism, in which case you probably won't be caring too much about DCS. Bottom line, it is extremely valuable for ALL divers (technical or otherwise) to learn to control their fears/panic and be proficient at dealing with emergencies while still at the bottom, instead of bolting to the surface. Yes, surfacing is always an option, but it is not always the best option. The best option is to prevent events from becoming emergencies or better yet, strive to have uneventful dives. Luck favors the prepared.

 

[DaleC]

There is a practical problem to educating yourself, with or without the help of a Mentor, until the time comes when you really need the card. In order to get the higher level card you needd from every agency I know, you have to go through the courses leading up to it.

I started with one tech agency, and I went through the first three levels of tech certification with them over a long period of time. Due to circumstances beyond my control, I had no choice but to switch agencies. That agency had a relatively reasonable crossover policy, so I did not have to repeat too many courses in order to get my certifications with them up to the level they were with my first agency, but it still took quite some time. My earlier training made it easier for me to go through the steps, but I still had to go through the steps.

Then a took a bunch of courses from that new agency before making the unavoidable decision to leave it and switch to another agency. Fortunately, I went back to my original agency, which meant I only had to go back to my old highest training level with them in order to continue. Had I gone to another agency, I would have had to start from scratch.

If you get great training from a Mentor (but no cards) over a period of years and then find out you need a trimix card to go further, when you go to get that trimix card, you will probably discover that you will first have to take the introduction to technical diving course and then go through all the steps that you have already gone through on your own. That is roughly what I had to do when I switched agencies, and I suspect it will be even harder if you walk up to an advanced tech instructor and say, "Please put me in your advanced trimix class without making me go through all the courses before that. A friend has shown me all that stuff, so I don't need to take those classes. Don't worry about your agency's policies--you can make an exception for me."

This is very true though I suspect it would not be a jump from self taught to advanced trimix. Probably more like air deco to mixed gas or occasionally, mixed gas to basic trimix - but the point is noted.
I had just such a discussion with our local UTD instructor when I was mapping out a trimix pathway with his agency. I did not insist on his making an exception for me however. we discussed the holistic approach of his regime and where I would probably start and why. A fairly civil and well thought out conversation.