Deco in caves

[JahJahwarrior]

Wats a cave 4?

A cave is 4 diving in, silly!


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[kelemvor]

Wats a cave 4?

The last section of full cave with NASE. I believe I need to plan and lead a cave dive with no mistakes, basically. I'm not ready yet . Had to stop diving for a few months due to a bum body.

 

[Germie]

As I wrote yesterday: deco is not covered in all full cave courses.
You can enter a cave course without any experience in technical diving. It is possible to do the cavern,-intro to cave, full cave in a ‘zero to hero’ traject. You can do this if you have an AOW cert. Yes, then you don’t have any experience with decodives. I was ART certified when I did this tdi zero to hero course and no stagecylinders where used in the course and no decodives done. In the iantd technical cave diver you use just 1 stage, so it is limited deco. So yes, a full cave course is not a decocourse. Planning ‘normal’ decodives is part of a decocourse (adv. Nitrox or trimix). But the aspects of making a diveplan in a cave is part of a full cave course. How far can you get in? (time at depth * P * rmv, where time at depth depends on swimmingspeed). A good instructor will tell you something about a diveplan with use of decogases if a student has already done decodives. After a full cave course you need to gain experience by diving in caves. And then step by step you can go further. If you are unsure about the use of stages in caves there are ‘multiple stage’ courses after a full cave course. Not all divers do/need that, but is an option if you have too much questions left. First do your complete full cave course, then go diving and go further step by step, get more and more experience after the course.

And yes I know from the fast swimming sportsdivers. But I am a slow swimmer when diving and no need to hurry and slow them down (and the viz is here most times max 2m, so that slows down too.)

 

[kensuf]

I'm a big believer in cave divers taking AN/DP in a cave environment (although some of the standards Nazis jump seem to want to jump on instructors for doing that unless the student is already full cave certified). Similarly, I am also a fan of cave divers taking trimix in a cave environment, as the planning and skill sets in a cave are substantially different than the planning and skill sets in offshore trimix diving. I actually re-took trimix in a cave environment just to get a better perspective on the challenges and nuances unique to trimix cave diving.

With some agencies, AN/DP can be taught in a cave environment if it's part of a cave course. The student will have to do a couple of additional dives beyond the minimum 8 for full cave, and all of the skills must be met, which includes shooting liftbags.

The disagreement comes when instructors take students that have not completed full cave into advanced cave environments (lower orange grove being the oft cited location, but eagles nest counts too). Instructors do not need to go to lower orange grove to get deeper than 100', Little River usually works pretty well. Worst case they can spend a day in Hudson Grotto and get to 130', or pony up for 40 Fathom Grotto.

 

[SillyQuestions]

In the following post, proper measurements are used. Guesses have been taken at silly measurements, they're probably wrong.

So I do a fair amount of cave exploration. Dry and wet, and the wet normally comes after the dry.

I discovered a 3rd sump into the system. The first and second sumps were known.

First sump 40 long and 3m deep (140ft long, 10ft deep). No problem here.

Second sump, perfect shaft to 21m (70ft) gradual slope to 50m (180ft) then 500m (1700ft?)at this depth, gradual slope to surface again.

You know in this instance you've got approx 1 hour at 50m depth. So you know you've got about 80mins of deco. Take enough gas, see what happens, if it's not enough, turn round. But in this place it is, so I carried on.

I found the third sump. I didn't have available gas for it. I left, came back later with two 3L (LP30s?) cylinders to check it didn't close down. I dived to 10m (30ft) deep and about 100m in (300ft). It didn't.

I came back with more gas, it went to 30m (100ft) deep at 400m (1300ft?) and continued downwards.

I came back with some 32%, 21/35 and a bottle of 50%. I found a shaft, still on going at 50m (180ft)

I came back with some 35/25, 15/55, 50% and O2. Dropped the shaft, at 68m (230ft?) it levels out for about 150m (450ft) and then starts to rise. I turned around at 40m.

I'm going back in February with a rebreather in February.

Basically, go slowly, learn the cave, understand how deco works and don't just blindly follow computer.

For example, as someone stated above "can't do deco at 20ft, so do it at 30ft"

With a conservative plan, why not have one person at 15, one at 20 and one at 25 and stick to the plan? Rather than using silly gases and doing much longer deco. Deco not an exact science by a long way and understanding this learning what wiggle room you have is quintessential to reasonably practicable and safe exploration.


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[Germie]

SillyQuestions, what you describes is on exploration level. I wrote my example on known caves, no exploration level. With explorations it can take dives and more dives and much more dives as you don't know what is coming. A cave course is for 'recreational cavediving', there are already lines in the cave etc. But of course it is nice to tell about such dives. But starting an exploration just after a full cave course is not an good idea.

 

[SillyQuestions]

What works in exploration works in tourist diving.

Go slowly, baby steps, know your stuff, don't blindly follow anything.


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[DA Aquamaster]

With some agencies, AN/DP can be taught in a cave environment if it's part of a cave course. The student will have to do a couple of additional dives beyond the minimum 8 for full cave, and all of the skills must be met, which includes shooting liftbags.

The disagreement comes when instructors take students that have not completed full cave into advanced cave environments (lower orange grove being the oft cited location, but eagles nest counts too). Instructors do not need to go to lower orange grove to get deeper than 100', Little River usually works pretty well. Worst case they can spend a day in Hudson Grotto and get to 130', or pony up for 40 Fathom Grotto.

I noted above my beef is primarily with NACD and NSS-CDS for NOT incorporating a formal process for teaching/learning decompression in advance of or in addition to the Cave/Full Cave course. The fact that other agencies have figured that out just adds impetus to the argument that it's a good idea.

As for going to someplace like 40 Fathom Grotto to get enough depth, it defeats the purpose of learning AN/DP skills in a cave environment as it's pretty much a non overhead dive.

I'll be right upfront and note that one of the dives in the AN/DP course Marci took (and that I audited to get exposure to AN/DP taught in a cave) was done in Lower Orange Grove and that another dive was to 145 ft just past the sand slide in Henley's Castle. The instructor, now retired, was one of the old guys who'd been around for decades, and had been heavily involved in instructor development. No one ever questioned his choice of dives in his classes.

It seems that this has only recently become a sin - and it smells rather badly cave country politics.

Consider the flawed logic here:

If a Cave instructor takes an Intro to Cave certified diver to 130' in Lower OG during their Apprentice or Cave training, it's just peachy as it's within the Apprentice and Cave depth limit of 130'. The student however is not required to have any specific classroom training on decompression or the use of high percentage nitrox mixes.

However if a Cave instructor takes that same Intro to Cave certified student to 130' in a TDI or IANTD AN/DP course in Lower OG, it's suddenly a mortal sin. Apparently that's because this same student, doing exactly the same dive, now has classroom training before hand in planning and executing a staged decompression dive using 1 or 2 high O2 percentage decompression mixes.

Same instructor, same student, better training in deco procedures, but a different course name = people trying to get an instructor thrown out.

100' has been given as the depth limit for AN/DP in this situation, but how realistic is it to certify a diver to 150' in AN/DP and only expose them to the same 100' depths they've already encountered. If the diver is Intro to Cave level in N FL, they've probably already dove to 100' (plus 4' to 6' more) in Little River. If they stay long enough to rack up deco on a first dive of the day, they either violate sixths (gasp! a standards violation for the instructor) or they just "simulate" the deco. Personally, I think giving an AN/DP card to a student who's never been below a 100' or done real deco is a dis-service and it sets the diver up with some serious confidence issues in the event they ever really want to do a deco dive.

Once again however, if a dive with that same Intro to Cave certified student is done below 100' to thirds with meaningful deco resulting, it's just fine in a Cave course - where of course no substantial decompression theory or procedure is required to be taught.

The logic being used by some folks (in the NACD in particular) to try to find an instructor at fault for a standards violation is fatally flawed.

The rational thing to do is to explicitly allow Intro to Cave certified students to be taught an AN/DP course (or the NACD equivalent) in a cave environment to the same limits that a Cave instructor is allowed to apply to an Apprentice or Cave student.

An even better idea would be to incorporate formal decompression training standards into Cave training conducted in areas like N FL, where full cave dives of meaningful length in 100' deep caves requires decompression. The same standard would not have to be applied in areas like MX where full cave training may never involved decompression, but the same decompression and high percentage O2 mix subjects should be covered to the same standards. After all, those dives may end up in a much deeper caves in MX or elsewhere.

 

[stuartv]

Consider the flawed logic here:

If a Cave instructor takes an Intro to Cave certified diver to 130' in Lower OG during their Apprentice or Cave training, it's just peachy as it's within the Apprentice and Cave depth limit of 130'. The student however is not required to have any specific classroom training on decompression or the use of high percentage nitrox mixes.

However if a Cave instructor takes that same Intro to Cave certified student to 130' in a TDI or IANTD AN/DP course in Lower OG, it's suddenly a mortal sin. Apparently that's because this same student, doing exactly the same dive, now has classroom training before hand in planning and executing a staged decompression dive using 1 or 2 high O2 percentage decompression mixes.

Same instructor, same student, better training in deco procedures, but a different course name = people trying to get an instructor thrown out.

Isn't there a difference between the two scenarios regarding what the student was taught in the classroom portion of their current class, prior to this hypothetical dive?

I mean, taking a cave student into a cave after doing classroom training on cave diving makes perfect sense. You didn't specify in the first example that a deco obligation is incurred, but maybe that is understood by people who know that cave?

Taking a DP student into a cave after doing classroom training on DP doesn't seem to make as much sense - unless they are already certified to do the same dive, only as a shorter, non-deco dive.

I am presuming that Intro to Cave is not sufficient to allow the 130' dive in Lower OG by itself. I don't know the standards nor that dive, so that could also be wrong. If the dive is something Intro certifies the diver to do anyway (as an NDL dive), then your example makes perfect sense.

Maybe I should have just posted "I don't know Lower OG or the cave diving standards. Can you explain more why your example makes sense?"

 

[DA Aquamaster]

Isn't there a difference between the two scenarios regarding what the student was taught in the classroom portion of their current class, prior to this hypothetical dive?

I mean, taking a cave student into a cave after doing classroom training on cave diving makes perfect sense. You didn't specify in the first example that a deco obligation is incurred, but maybe that is understood by people who know that cave?

Taking a DP student into a cave after doing classroom training on DP doesn't seem to make as much sense - unless they are already certified to do the same dive, only as a shorter, non-deco dive.

I am presuming that Intro to Cave is not sufficient to allow the 130' dive in Lower OG by itself. I don't know the standards nor that dive, so that could also be wrong. If the dive is something Intro certifies the diver to do anyway (as an NDL dive), then your example makes perfect sense.

Maybe I should have just posted "I don't know Lower OG or the cave diving standards. Can you explain more why your example makes sense?"

Sure.

If I am an Intro to Cave certified diver - able to do dives in caves on the main line (no jumps, etc) - and I'm a student in a full cave class, a cave instructor could take me to 130' in a cave and we could stay there long enough to incur significant deco, and there is no standards violation involved.

However, if I am an Intro to Cave certified diver - able to do dives in caves on the main line (no jumps, etc) - and I'm a student in an AN/DP class, a cave instructor could take me to 130' in a cave and we could stay there long enough to incur significant deco, and some folks will call that a standards violation.

In both cases, for the purposes of training, the instructor is taking me one level above my certification level. The folks who scream "standards violation!" are in essence claiming I'm two levels above my training level in an ANDP class in a cave, as I'm in a full cave situation, AND I'm taking a deco class (from another agency).

But it's the same situation in both cases, as I'm doing training, in a cave, with a full cave instructor. The only differences are the course title and the cert agency involved. .