O2 Bottle for Cavern, Cave or Deep OW

[dewdropsonrosa]

Next time you're in Mexico and get tired of the mosquitos and crawling thru the jungle, come over to Cozumel and lets do some diving - I live here full time!

Are there any options for extended dives on doubles in Cozumel? If there's some way to do a two-hour drift with whatever small amount of deco, that's going on my bucket list.

 

[ChuckP]

Are there any options for extended dives on doubles in Cozumel? If there's some way to do a two-hour drift with whatever small amount of deco, that's going on my bucket list.

Deep Exposure is one company that does them, I can take you too with another boat. There's a few options, most frown on the deco, I enjoy it though.

 

[grantctobin]

Let's start with - I never said I was going to do any of those things. I can do an accelerated decompression dive in 50 ft of water, exceeding 100 ft END is not required, and nothing I stated said anything about how deep the theoretical dive I was talking about would be. As for your inability to figure out how someone could incur a deco obligation without exceeding 1/6ths on their penetration, I'm sorry you can't grasp that but it's easily possible. For instance, go in the cavern to 90 ft (10 minutes into the dive, don't penetrate any farther, turn around and start slowly coming back out, but take your time coming back out without coming up quickly so that you spend the next 30 minutes at an average of 60 ft on your way out and you didn't penetrate past 1/6ths, yet you've got a nice little deco obligation (7 minutes of 50% using 30/70 gf according to multideco).

So, in conclusion, not only did you incorrectly accuse me of planning to dive past my certification level despite the extremely obvious fact that I was asking a question and NOT pretending to know everything and be better than any training, then you invent some parameters for that hypothetical dive AND have your inventions violate more standards, but you also demonstrated that you're incapable of figuring out a dive plan that took me 2 minutes to develop in multideco to show you how it could be done? Oh, and you did ALL of that without stating one reason why the proposed dive would be more dangerous than just doing a cavern dive in Paradise springs that didn't involve deco? Thanks for all that insight.

While blunt, I think RJack is well intentioned and has your safety in mind. You’ve escalated.

Your PADI cavern certification isn’t held in very high regard. Their allowance of instructors to self certify as cavern instructors scares the hell out of me but I don’t know who taught your class and his or her background.

While Paradise (asininely, but w their own monetary and tourist interests in mind) allows OW divers to dive there, it’s an overhead environment. If you move past the sign into the larger area at the bottom, it’s not possible to see daylight. You add a few open water divers that get in the water right after you and moonwalk down the line, visibility near the entrance goes below 20 feet quite quickly. Now, you’re in a cave as visibility has sufficiently deteriorated. There’s no guarantee that your starting vis is going to remain unchanged. Now you’re in a cave, with a deco obligation, without a verified ability to safely manage yourself (let alone be an asset to your team) in such an environment.

To throw another wrench and because you’re arguing semantics with your certs, at 90° you may have already violated your distance limits of your cert. It’s greater than a 45degree angle measured on the line which brings total distance to greater than 130’ penetration. Perhaps PADI cavern limit is further than NSS NACD etc. Happy to be corrected on that point.

Lastly, the average cavern student (let alone self certed instructors) doesn’t have the line etiquette to not get him- or herself entangled when adding things like a slung bottle or other gear.

@kensuf will chime in. I think the other reason deco isn’t allowed at cavern level (in addition to all of Tom’s and Richard’s above), is that cavern class is allowed in a single. A single is irresponsible for decompression diving and it would be a pity to allow someone on a single tank conduct deco in a cavern (that can and does turn to a cave in a few fin kicks).

TLR a cavern deco dive is a technical dive on a recreational cert.

How many cavern dives do you have? How many decompression dives in open water?

 

[jlcnuke]

While blunt, I think RJack is well intentioned and has your safety in mind. You’ve escalated.

Your PADI cavern certification isn’t held in very high regard. Their allowance of instructors to self certify as cavern instructors scares the hell out of me but I don’t know who taught your class and his or her background.

While Paradise (asininely, but w their own monetary and tourist interests in mind) allows OW divers to dive there, it’s an overhead environment. If you move past the sign into the larger area at the bottom, it’s not possible to see daylight. You add a few open water divers that get in the water right after you and moonwalk down the line, visibility near the entrance goes below 20 feet quite quickly. Now, you’re in a cave as visibility has sufficiently deteriorated. There’s no guarantee that your starting vis is going to remain unchanged. Now you’re in a cave, with a deco obligation, without a verified ability to safely manage yourself (let alone be an asset to your team) in such an environment.

To throw another wrench and because you’re arguing semantics with your certs, at 90° you may have already violated your distance limits of your cert. It’s greater than a 45degree angle measured on the line which brings total distance to greater than 130’ penetration. Perhaps PADI cavern limit is further than NSS NACD etc. Happy to be corrected on that point.

Lastly, the average cavern student (let alone self certed instructors) doesn’t have the line etiquette to not get him- or herself entangled when adding things like a slung bottle or other gear.

@kensuf will chime in. I think the other reason deco isn’t allowed at cavern level (in addition to all of Tom’s and Richard’s above), is that cavern class is allowed in a single. A single is irresponsible for decompression diving and it would be a pity to allow someone on a single tank conduct deco in a cavern (that can and does turn to a cave in a few fin kicks).

TLR a cavern deco dive is a technical dive on a recreational cert.

How many cavern dives do you have? How many decompression dives in open water?

I escalated because he didn't pay attention to the post so that he could see it was asking a question. Again, someone is now missing the point as a result. The point (and entire writing, wording, etc.) of my post was to ask what is the reason, if any, for the no-deco in a cavern for cavern certified divers with deco certification? I.e. "what is the danger here that doesn't exist when deco is not part of the dive"? The specifics of some randomly chosen hypothetical dive I chose to illustrate a scenario at a randomly chosen dive spot are completely immaterial. It could be "cavern 001", which has a 10' deep overhanging rock cropping at 20 ft and a depth of 80 ft below the overhead spot. It was a hypothetical question asking for the reason for the stated restriction, not something asking for a holier than thou high-horse lecture on exceeding stated certification limitations - which certainly none of my posts even alluded to wanting to do/planning to/having done, and which no one here stated they planned or wanted to do in a cavern. Tbone and others managed to figure that out quite simply, I'm not sure how others are completely missing that quite obvious fact.

Quite frankly, I'd question the training of anyone cavern certified that suddenly couldn't manage the dive just because they added a deco/stage bottle. If that suddenly causes issues following the line without getting entangled, they've got to be doing something wrong. Maybe, though, the restriction exists because the standard for being able to follow a line without getting yourself entangled in it is so poorly done by a bunch of students out there /shrug, but if that were the case, I'd think ensuring they could do things safely when certified would be a much better option than assuming every certified cavern diver was incompetent. But at least you managed to put forth a reason that may be an answer to my question.

Also, since no one's talking about actually doing any cavern dives (with or without deco) here, I don't think my personal dive stats are relevant to the thread.

 

[Manatee Diver]

Next time you're in Mexico and get tired of the mosquitos and crawling thru the jungle, come over to Cozumel and lets do some diving - I live here full time!

There is diving that doesn't involve getting bitten by mosquitoes?

I will hit you up the next time I am here, thinking about another trip in spring.

 

[lermontov]

That does seem a little strange, I'd think a wreck penetration is no less difficult then a cavern dive but I ain't there yet either.

and the irony is I did a 90 minute 60m trimix dive on my ccr mod 2 in the same spot as my basic cave dive, hmm wonder if i can count that as part of my basic cavern dive numbers

 

[PfcAJ]

Quite frankly, I'd question the training of anyone cavern certified that suddenly couldn't manage the dive just because they added a deco/stage bottle. If that suddenly causes issues following the line without getting entangled, they've got to be doing something wrong. Maybe, though, the restriction exists because the standard for being able to follow a line without getting yourself entangled in it is so poorly done by a bunch of students out there /shrug, but if that were the case, I'd think ensuring they could do things safely when certified would be a much better option than assuming every certified cavern diver was incompetent. But at least you managed to put forth a reason that may be an answer to my question.

I think you haven’t observed many cavern divers.

It’s a familiarization course for open water divers with an open water configuration.

Adding more gear when managing the line, silt, light, buddy, and cave is not helping your situation. Rjack mentioned a fatality at Cow, but I think the one he’s referencing was actually at School Sink.

Iirc one of those cavern divers died from breathing their oxygen bottle at depth.

Overhead dives (deco, cave, wreck) are not to be trifled with.

 

[tursiops]

Perhaps PADI cavern limit is further than NSS NACD etc.

PADI training limit is 70 ft max depth, 130 ft combined horizontal and vertical distance, 40 ft minimum viz, cavern exit always visible. No deco of course, single cylinder.

 

[jlcnuke]

I think you haven’t observed many cavern divers.

It’s a familiarization course for open water divers with an open water configuration.

Adding more gear when managing the line, silt, light, buddy, and cave is not helping your situation. Rjack mentioned a fatality at Cow, but I think the one he’s referencing was actually at School Sink.

Iirc one of those cavern divers died from breathing their oxygen bottle at depth.

Overhead dives (deco, cave, wreck) are not to be trifled with.

Absolutely no one, anywhere here in this thread, has suggested trifling with overhead dives. The simple question was "what is the rationale for a cavern diver, certified to safely dive in a cavern, who is also a decompression procedures diver, certified to do decompression dives, not being able to do the two at the same time?" Not - "hey, is it cool for cavern divers to go do deco dives inside caves?" I appreciate those who were able to answer the question instead of going off on irrelevant tangents, but I'm pretty tired of responding to the irrelevant tangents at this point honestly.

 

[kensuf]

This post really encapsulates most of everything I would say: O2 Bottle for Cavern, Cave or Deep OW

Cavern is meant to be an introductory safety course to the overhead environment, teach people about the risks associated with the cave environment, the basics of how to run a reel, team communication, some propulsion techniques, and a few basic emergency skills.

There's a thing called task loading, which happens to all of us when we have to think about performing a task rather than being able to do the task automatically because we are so experienced that we can perform it via muscle memory. Running a reel, maintaining proper trim and buoyancy, and simply monitoring your gas limits while being in the overhead environment adds a fair bit of task loading to people new to the environment.

Task loading leads to perceptual narrowing. I like to describe task loading and perceptual narrowing in IT terms; we all have a finite amount of bandwidth between our ears (capacity). We consume that available bandwidth every time we have to think about how to do a task. When we are consuming that capacity, we have diminished our ability to observe other things around us, we call that perceptual narrowing. When you have perceptual narrowing, you literally become oblivious to things around you, such as your buddy telling you they are low on air, or the fact that your feet are laying in the ground kicking up silt. Perceptual narrowing can get you into deep trouble.

Decompression diving, holding stops, working with stage bottles, and the like also adds a fair bit of task loading for people new to those skills.

By keeping cavern diving as a non-deco dive, you're reducing the unnecessary task loading and risks of perceptual narrowing. View cavern diving for what it is -- a set of training wheels as you work towards developing and mastering the basic skills of cave diving before going on to the next step.