Decompression Course

[FinnMom]

Returning to the. original question of this thread

Another option is Advanced recreational trimix through IANTD. Then you get deco and trimix, plus a ticket to 48m

This is what I would have said. Exactly what you are looking for:
* a single class
* focused on recreational divers who want to add the capability to do deep dives with a better gas, i.e. mixed gas
* certifies you all the way to 48m, which is plenty darn deep for divers who consider their diving to be recreational
* can also be done with much more recreational gear configurations than most other trimix classes

BTW the kindle store has exactly 1 rec trimix book (don't recall title), fairlly inexpensive and well worth the money.
When I took the class we never used the textbook, just the instructor's notes because the text was English-speaking and most of the students were not. I saw the official text and it was not good: talked at length about tables in an age of dive planning software, presented calculations in a very unclear manner (this from someone who loved math) and had 15 differnt fonts in crazy colors everywhere - looked like a kid with a Crayola 64 box had just gone nuts.
The kindle book was pretty good, Deco for Divers is exceptionally good for learning what a trimix-level diver should know about deco theory, gases, physiology and decompression illness. Amazingly enough it's presented in a way that makes it recreationally readable.

 

[rivers]

Thanks for the reply... I think that some of the subtleties of this can be lost in translation, but I'm always interested in learning about different approaches to diving...





So, are you a dive professional? Do you carry insurance? Do you get paid to do this, or is it just an informal buddy relationship?





Don't know about that. Unless you are running an open water class, I would expect every diver to have a plan for what to do in case of separation. Maybe you have better vis there!






So you would do a deco dive to 40 m with a diver who had 20 dives? Since you aren't an instructor, and this wouldn't be in the context of a training dive, would you really take such a diver into deco simply because you are a DM equivalent?

In my experience, most tech instructors want you to have a very solid foundation before you get even close to real deco in open water. In addition to working on necessary skills, our course includes a long profile with simulated deco, so that you have the opportunity to follow runtime before you are subject to the danger of DCS from a failure to follow that plan.




I guess I was more concerned about the gas loss in cases of a profile involving decompression stops, and having enough gas to finish the schedule.

So what is your definition of a technical dive?

So you define a technical dive as a dive involving accelerated deco with a deco bottle, but decompression on air doesn't count as technical?

Mike, the concept of deco and club diving in the UK and Europe was something I had to wrap my head around when I first moved to the UK a few years back.
In the club systems (BSAC, SAA, CMAS, ScotSAC, etc), once you hit what is essentially the 2nd tier in training, you are taught and allowed to complete dives that involve mandatory deco. But, at least in BSAC, if it is a club sanctioned dive, the Diving Officer (DO) has to essentially okay it. So while a sports diver with say 30 or so dives may technically be able to complete a deco dive, the DO can turn around and say "actually no you can't, you don't yet have the experience nor are you equipped to do so", if that makes sense. I know plenty of sports divers in my club who are quite happy doing single tank bimbles, and have no interest in getting into mandatory decompression. Then there are some like me who are quite happy to do a bit of deco on dives that warrant it. But, I also dive manifolded twins and a 7 litre stage (either back gas or a rich deco gas). As a sports diver, you can also take courses such as accelerated deco, trimix, etc. There are certain requirements that must be met (prerequisite courses, buoyancy standards, number of dives, etc) in order to take those courses.
I don't consider myself a technical diver. I'm currently limited to a max depth of 35m. But, I regularly carry out dives that involve mandatory decompression, and I am allowed to accelerate my deco (although I don't. I'm not racking up enough deco at the moment to worry about it, but it was a good course and I'm glad I did it). Hopefully, if all goes well on my GUE Rec 3 course next week, I'll be able to complete a decompression dive to 40m using trimix. But again, it's only a recreational course.
Mandatory deco isn't as big a deal over on this side of the pond. For some, it just becomes a regular part of diving once you hit a certain point in one's diving career. Maybe it's because we don't get into the sea as often as we hope, so when we do, we take full advantage...

 

[KenGordon]

What is the difference between Rec3 and a GUE Tech course which goes to 40m on trimix that makes it recreational rather than technical?

 

[rivers]

Rec 3: 40m limit, 30/30 and 21/35 for trimix, 32% as a "deco gas", 15 minutes of deco and the failures aren't as "intense". It's like baby tech diving, but if you really cock things at least you have a gas you breathe from depth to the surface in your stage
Tech 1: 51m limit, 18/45, 21/35, and 30/30 (i think) for trimix, 50% and 100% deco gas., 30 minutes (i think) of deco, and loads more failures

i don't know if that's all the differences, but what i do know

 

[alewar]

I guess if the CMAS equivalent of open water diver involves much more training and weeds out people who aren't very comfortable in the water, that makes sense. Personally, that would worry me.

I think the CMAS approach works in Germany not because the training is better, but because people don't normally dive bellow 15-20m. Most diving is done in our artificial lakes and bellow 15m it's cold, dark and with little to see. There is normally no point going deeper except for training purposes. When diving abroad you probably end up in a group with divers from other agencies and diving within NDL, so most people don't go into deco there either.

 

[mathauck0814]

technical dive begins with advanced nitrox, when bringing a rich nitrox pony and switching to.
decompression is not technical, our drivers are trained to.
basic nitrox is not technical, our divers know decompression, know how to compute MOD and MIX.

I suppose in the end the difference is this:

Decompression stops are required when you've reached a point where surfacing would be dangerous and you have to stay in the water. If you're doing "decompression" on a "normal dive" and you don't have the redundancy that a more traditional technical diving kit provides you've got to roll the dice with your odds of what may happen when you surface.

So can you do decompression diving on a single cylinder? Sure, you can. You just have to be aware that a failure causing loss of gas can put you in a place where you can get hurt.

It's all about personal risk assessment and what's acceptable. CMAS gives their divers a tool that the mainstream agencies don't. If that's how you were taught to dive, I'm not going to crap on it. The point is that the OP didn't learn to dive that way, but is talking about somehow piggybacking on another agencies' practices when he doesn't know them himself.

 

[boulderjohn]

I suppose in the end the difference is this:

Decompression stops are required when you've reached a point where surfacing would be dangerous and you have to stay in the water. If you're doing "decompression" on a "normal dive" and you don't have the redundancy that a more traditional technical diving kit provides you've got to roll the dice with your odds of what may happen when you surface.

So can you do decompression diving on a single cylinder? Sure, you can. You just have to be aware that a failure causing loss of gas can put you in a place where you can get hurt.

It's all about personal risk assessment and what's acceptable. CMAS gives their divers a tool that the mainstream agencies don't. If that's how you were taught to dive, I'm not going to crap on it. The point is that the OP didn't learn to dive that way, but is talking about somehow piggybacking on another agencies' practices when he doesn't know them himself.

I think I am going to give an accurate accounting of some history, but I will be happy if those more knowledgeable than I wish to correct me.

When recreational diving began, most people were using things like the U.S. Navy tables for guidance. There was then no differentiation between recreational (or sport) diving and technical diving. It was just diving. The U.S. Navy Air tables showed that some dives required decompression stops, and some dives didn't. They showed when you had to do those stops and for how long, and you did those stops using the same air you were using throughout the dive.

The U.S. Navy tables, however, were not really suited to the growing recreational dive market. They were designed for deeper, longer dives, and they used a very slow tissue compartment to determine surface intervals. They didn't have to worry about surface intervals, because Navy divers usually did only one dive a day. This made it really hard for sport divers to get in a two tank dive day. Research showed that typical sport divers did not need to be guided by such a slow compartment, and new tables, notably the PADI RDP, were developed for that purpose. Those tables did not include decompression schedules, and they were called No Decompression Tables. Although they supposedly did not contain decompression stops, they actually did--those are the mandatory, required safety stops on the dives that approach no decompression limits. There is not much difference between those and a mandatory decompression stop at the same depth. These tables and concepts became the norm of the industry.

Soon there was a gap between recreational (sport) diving and a new concept called technical diving. A sharp dividing line was drawn, and the simple decompression dives that used to be a routine part of the training for the U.S. Navy tales became part of the technical diving world.

So the CMAS program, as I see it, is just a continuation of the way diving was taught decades ago, before the dividing line between recreational and technical diving was created.

 

[mathauck0814]

I think I am going to give an accurate accounting of some history, but I will be happy if those more knowledgeable than I wish to correct me.

When recreational diving began, most people were using things like the U.S. Navy tables for guidance. There was then no differentiation between recreational (or sport) diving and technical diving. It was just diving. The U.S. Navy Air tables showed that some dives required decompression stops, and some dives didn't. They showed when you had to do those stops and for how long, and you did those stops using the same air you were using throughout the dive.

The U.S. Navy tables, however, were not really suited to the growing recreational dive market. They were designed for deeper, longer dives, and they used a very slow tissue compartment to determine surface intervals. They didn't have to worry about surface intervals, because Navy divers usually did only one dive a day. This made it really hard for sport divers to get in a two tank dive day. Research showed that typical sport divers did not need to be guided by such a slow compartment, and new tables, notably the PADI RDP, were developed for that purpose. Those tables did not include decompression schedules, and they were called No Decompression Tables. Although they supposedly did not contain decompression stops, they actually did--those are the mandatory, required safety stops on the dives that approach no decompression limits. There is not much difference between those and a mandatory decompression stop at the same depth. These tables and concepts became the norm of the industry.

Soon there was a gap between recreational (sport) diving and a new concept called technical diving. A sharp dividing line was drawn, and the simple decompression dives that used to be a routine part of the training for the U.S. Navy tales became part of the technical diving world.

So the CMAS program, as I see it, is just a continuation of the way diving was taught decades ago, before the dividing line between recreational and technical diving was created.

Part of that "modernization" was realizing that things can go tits up in given situations and designing procedures and standards to address them. No one strapped a set of doubles or developed the isolation manifold, "because it looks cool" or "chicks dig it". We have those things because there was a real problem to be solved.

If CMAS is a continuation of old ideas, that's fine but it seems to ignore some particularly logical ways of doing things.

All of which is neither here nor there. If CMAS has old school practices and they're teaching their divers to dive in a way that they're not ending up dead in droves, that's cool. The OP is a PADI instructor with no CMAS certification. He wasn't trained in "the way diving was taught decades ago" and has fewer tools than a technical diver or a CMAS diver would have in that specific scenario.

The "line" is more real than you're giving it credit for, I think. Unless you believe decompression to be just as optional as a safety stop or feel that you're somehow more physiologically tolerant than the decompression model, on the other side of that line you put yourself at a greatly increased risk of injury.

 

[boulderjohn]

Part of that "modernization" was realizing that things can go tits up in given situations and designing procedures and standards to address them. No one strapped a set of doubles or developed the isolation manifold, "because it looks cool" or "chicks dig it". We have those things because there was a real problem to be solved.

I agree. I am just trying to explain what I perceive to be the history of this approach. I am myself a tech instructor and would much prefer that divers learn and use the additional safety factors that were learned through technical diving over those decades.

 

[doctormike]

Mike, the concept of deco and club diving in the UK and Europe was something I had to wrap my head around when I first moved to the UK a few years back.
In the club systems (BSAC, SAA, CMAS, ScotSAC, etc), once you hit what is essentially the 2nd tier in training, you are taught and allowed to complete dives that involve mandatory deco. But, at least in BSAC, if it is a club sanctioned dive, the Diving Officer (DO) has to essentially okay it. So while a sports diver with say 30 or so dives may technically be able to complete a deco dive, the DO can turn around and say "actually no you can't, you don't yet have the experience nor are you equipped to do so", if that makes sense. I know plenty of sports divers in my club who are quite happy doing single tank bimbles, and have no interest in getting into mandatory decompression. Then there are some like me who are quite happy to do a bit of deco on dives that warrant it. But, I also dive manifolded twins and a 7 litre stage (either back gas or a rich deco gas). As a sports diver, you can also take courses such as accelerated deco, trimix, etc. There are certain requirements that must be met (prerequisite courses, buoyancy standards, number of dives, etc) in order to take those courses.
I don't consider myself a technical diver. I'm currently limited to a max depth of 35m. But, I regularly carry out dives that involve mandatory decompression, and I am allowed to accelerate my deco (although I don't. I'm not racking up enough deco at the moment to worry about it, but it was a good course and I'm glad I did it). Hopefully, if all goes well on my GUE Rec 3 course next week, I'll be able to complete a decompression dive to 40m using trimix. But again, it's only a recreational course.
Mandatory deco isn't as big a deal over on this side of the pond. For some, it just becomes a regular part of diving once you hit a certain point in one's diving career. Maybe it's because we don't get into the sea as often as we hope, so when we do, we take full advantage...

Got it... interesting! See, always good to learn about different cultures....