girton1981
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Hello all. I was wondering at what level of training does one start to use decompression diving? Are there classes just for that or is it part of another class? 
Decompression Diving???
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You can start decompression diving ant time you like.
It's best to take a class though and the agency's that teach it like to see a decent amount of diving experience before you start their courses.
Each Agency has their own minimum cert level before you begin.
It's best to take a class though and the agency's that teach it like to see a decent amount of diving experience before you start their courses.
Each Agency has their own minimum cert level before you begin.
Having never done any deco dives myself, you'll get better answers from others I'm sure, but I'll attempt an answer:
All "recreational" diving is "no deco" diving. When you begin doing decompression dives, that falls in the "technical diving" category, and requires additional training, equipment, and experience.
Training:
Most agencies have some sort of deco course, although the technically inclined ones (TDI, GUE, etc) likely have the better courses (I'm guessing here).
Many divers start the transition with something like GUE's "DIR-Fundamentals" or an "Intro to Tech" kind of class.
Equipment:
Most decompression diving is done with double cylinders, sometimes with a stage bottle for a decompression gas. Single cylinders usually don't have enough gas for a long deep dive plus decompression gas. Plus, when going to the surface isn't an option, you need a redundant source of breathing gas.
Experience:
Most courses require a certain number of dives (sometimes a certain number beyond a certain depth limit, etc). This is one way to compare your experience with what's expected. Another is your personal experience (review your log book) and comfort level with what you've done, and the kind of diving you have in mind. My own personal recommendation would be to log 100 dives (a nice round number, but somewhat arbitrary) before considering technical diving (which includes mandatory decompression obligations).
Keep in mind that I haven't done any deco dives, but will eventually... so read up on these forums, keep asking questions, and dive as much as possible. =)
All "recreational" diving is "no deco" diving. When you begin doing decompression dives, that falls in the "technical diving" category, and requires additional training, equipment, and experience.
Training:
Most agencies have some sort of deco course, although the technically inclined ones (TDI, GUE, etc) likely have the better courses (I'm guessing here).
Many divers start the transition with something like GUE's "DIR-Fundamentals" or an "Intro to Tech" kind of class.
Equipment:
Most decompression diving is done with double cylinders, sometimes with a stage bottle for a decompression gas. Single cylinders usually don't have enough gas for a long deep dive plus decompression gas. Plus, when going to the surface isn't an option, you need a redundant source of breathing gas.
Experience:
Most courses require a certain number of dives (sometimes a certain number beyond a certain depth limit, etc). This is one way to compare your experience with what's expected. Another is your personal experience (review your log book) and comfort level with what you've done, and the kind of diving you have in mind. My own personal recommendation would be to log 100 dives (a nice round number, but somewhat arbitrary) before considering technical diving (which includes mandatory decompression obligations).
Keep in mind that I haven't done any deco dives, but will eventually... so read up on these forums, keep asking questions, and dive as much as possible. =)
There are some of us who would say that all diving is decompression diving . . . 
I assume you are asking about staged decompression for deeper, longer dives. This is a big step away from recreational, no-stop diving, because you now no longer have the surface for an option if anything goes wrong. Therefore, the equipment changes to provide greater redundancy (double tanks) and the training is much more intense, to make sure you can solve problems underwater while maintaining your basic diving skills.
As mentioned, for many people the first step is an Intro to Tech or Fundies class. This will generally introduce the higher standard of skills required for technical diving, as well as work on facility with the new equipment. Where you go from there depends on the agency, because they break it down differently.
Although it is quite possible to go into deco and do your hang without taking a class about it, I would recommend against that very strongly. This is definitely a case of "you don't know what you don't know", and good instruction will help you avoid a number of potentially dangerous or fatal errors.
I assume you are asking about staged decompression for deeper, longer dives. This is a big step away from recreational, no-stop diving, because you now no longer have the surface for an option if anything goes wrong. Therefore, the equipment changes to provide greater redundancy (double tanks) and the training is much more intense, to make sure you can solve problems underwater while maintaining your basic diving skills.
As mentioned, for many people the first step is an Intro to Tech or Fundies class. This will generally introduce the higher standard of skills required for technical diving, as well as work on facility with the new equipment. Where you go from there depends on the agency, because they break it down differently.
Although it is quite possible to go into deco and do your hang without taking a class about it, I would recommend against that very strongly. This is definitely a case of "you don't know what you don't know", and good instruction will help you avoid a number of potentially dangerous or fatal errors.
Calw wrote
OK, so what's going on here?
The OP apparently has the basic training which teaches about "NDL's" (no decompression limits) and that it is different from "Decompression" diving (i.e., "technical" diving). Not to make too fine a point, BUT, TSandM is "technically" correct -- ALL diving involves decompression because as soon as we start breathing compressed air underwater, we start loading our tissues with Nitrogen (the basic gas) which, once we go up, must be unloaded from those same body tissues -- that is, the tissues must "decompress."
OP -- as far as I can determine, the REAL difference between "recreational" diving and "technical decompression" diving is merely the fact that, under the "rules" of recreational diving, you ALWAYS have the option of going directly to the surface and completing your "decompression" in that "big air tank in the sky" -- the surface -- without a significant risk of decompression illness. This is NOT true of "technical decompression diving" where the diver needs to do some (most, all?) of her decompression under water -- OR ELSE face a significant risk of "decompression illness."
It is NOT that the recreational diver doesn't go through decompression, it is just that the recreational diver has the "safe" option of doing so on the surface.
Regarding your specific question -- You really SHOULD be "using decompression diving" at all times in all of your diving. When you "plan your dive" you should be thinking about how to decompress in the most efficient, and safe, way for you. By doing this planning you can then "dive your plan" in a way that makes you feel good when you finally get out of the water. In addition, not only should you be planning your "decompression strategy" (for example, are you going to ascend directly to the surface as you would when you typically do a dive on a wreck and if so, do a safety stop, ascend at 30 ft/min, etc., or are you going to swim upslope as you would when doing a typical shore dive and then "just spend time in the shallows" -- all those decisions) but that also gives you the opportunity to plan on how much air you need and when you turn your dive, etc.
Of course, you can always use the time tested strategy of "I'm just going to look at my computer and do what it tells me to do -- and I'm going to turn around when I've used half my air!" That actually works most of the time and you then don't have to worry about this planning stuff!
TSandM wrote
OK, so what's going on here?
The OP apparently has the basic training which teaches about "NDL's" (no decompression limits) and that it is different from "Decompression" diving (i.e., "technical" diving). Not to make too fine a point, BUT, TSandM is "technically" correct -- ALL diving involves decompression because as soon as we start breathing compressed air underwater, we start loading our tissues with Nitrogen (the basic gas) which, once we go up, must be unloaded from those same body tissues -- that is, the tissues must "decompress."
OP -- as far as I can determine, the REAL difference between "recreational" diving and "technical decompression" diving is merely the fact that, under the "rules" of recreational diving, you ALWAYS have the option of going directly to the surface and completing your "decompression" in that "big air tank in the sky" -- the surface -- without a significant risk of decompression illness. This is NOT true of "technical decompression diving" where the diver needs to do some (most, all?) of her decompression under water -- OR ELSE face a significant risk of "decompression illness."
It is NOT that the recreational diver doesn't go through decompression, it is just that the recreational diver has the "safe" option of doing so on the surface.
Regarding your specific question -- You really SHOULD be "using decompression diving" at all times in all of your diving. When you "plan your dive" you should be thinking about how to decompress in the most efficient, and safe, way for you. By doing this planning you can then "dive your plan" in a way that makes you feel good when you finally get out of the water. In addition, not only should you be planning your "decompression strategy" (for example, are you going to ascend directly to the surface as you would when you typically do a dive on a wreck and if so, do a safety stop, ascend at 30 ft/min, etc., or are you going to swim upslope as you would when doing a typical shore dive and then "just spend time in the shallows" -- all those decisions) but that also gives you the opportunity to plan on how much air you need and when you turn your dive, etc.
Of course, you can always use the time tested strategy of "I'm just going to look at my computer and do what it tells me to do -- and I'm going to turn around when I've used half my air!" That actually works most of the time and you then don't have to worry about this planning stuff!
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Blackwood
Contributor
And further that any diving done for fun is "recreational" regardless of whether there is an overhead environment (artificial or otherwise).
Addressing your question (?) all is impossible. So long as you have water above you (i.e. an ambient pressure drop between where you are and where you are going), there is decompression left to do*, and that decompression occurs at the surface. We generally call that the 'surface interval'.
*I suppose if you hung for an inordinate amount of time on Oxygen, pulmonary issues aside, you could say that you have no 'inert gases' left to decompress.
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BabyDuck
Contributor
to answer the op plainly - yes, there are classes for deco diving. the most common way to present deco is in two classes usually called 'advanced nitrox and decompression procedures', which can be taught separately but are usually combined. these classes are offered (perhaps under slightly different names) by several agencies - i'm using tdi, but there are others, and remember - it's not the agency, it's the instructor!
The posts above have addressed the semantics.
The major philosophical difference with decompression diving at depths and times outside the normal no decompresion limits is that you need to accept that you will have to deal with any emergency underwater without the option of a direct ascent to the surface.
That can be a biggy as many newer divers' first thought is to bolt for the surface if there is a problem. In contrast techical/decompression divers will almost by default work the problem and not consider an ascent to the surface while in a soft (deco only) or hard (inside a cave or wreck) overhead environment.
The other major challenge is that gas planning becomes much more critical both in terms of the rate at which you use it and the reserves needed to complete the dive safely.
Way back when (pre-mid 1980's) emergency deco procedures were taught as part of the PADI AOW course, but that would just not happen today.
TDI offers a Deco Procedures course that is usually taken along with Advanced Nitrox to allow accellerated deco using deco mixes with O2 percentages between 50% and 100%. That tends to be the first course in the SDI/TDI series where deco is normally done.
The major philosophical difference with decompression diving at depths and times outside the normal no decompresion limits is that you need to accept that you will have to deal with any emergency underwater without the option of a direct ascent to the surface.
That can be a biggy as many newer divers' first thought is to bolt for the surface if there is a problem. In contrast techical/decompression divers will almost by default work the problem and not consider an ascent to the surface while in a soft (deco only) or hard (inside a cave or wreck) overhead environment.
The other major challenge is that gas planning becomes much more critical both in terms of the rate at which you use it and the reserves needed to complete the dive safely.
Way back when (pre-mid 1980's) emergency deco procedures were taught as part of the PADI AOW course, but that would just not happen today.
TDI offers a Deco Procedures course that is usually taken along with Advanced Nitrox to allow accellerated deco using deco mixes with O2 percentages between 50% and 100%. That tends to be the first course in the SDI/TDI series where deco is normally done.
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To answer the OP post, yes there are specific classes that you need to take to learn how to plan and conduct decompression dives. However, you really need to have a strong, and I mean strong, foundation of the recreational skills. That is buoyancy control, trim, propulsion, situational awareness, etc. That is why Intro to Tech type courses are good (when ran by a good instructor), in that they teach you what you will need to look like in order to be successful in a technical diving class. Plus they are a lot of fun.
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