Cavern with single tank?

[rjack321]

In the past I would have said cavern in a single tank was ridiculous - the cavern is just a temporarily lit cave afterall. The sun goes down, dark clouds can come up, only a tiny bit of silt or percolation can obscure what little light gets to the back etc. But history has proven that cavern in doubles just gives you a whole lot more rope to hang yourself with after class. A single tank is a much firmer enforcer of not going so far.

The "cavern tours" in MX have had some fatalities but they are almost always medical events. Overhead-wise they are some of the safest trust me dives you can do - mostly because they are so shallow so there is tons of time to solve problems even at stressed consumption rates.

 

[MichaelMc]

I'm in the 'I want good cavern as self proof of good skills' camp. And to appreciate Cenotes. Maybe with Under the Jungle or someone in Florida.

I appreciate classes shifting to reduce the risk of leaving the cavern conditions. That risk seems real. Maybe keeping cavern rec single tank keeps them an extra step back from over extending in doubles. Do cavern/cave adjacent areas limit what cavern card holders are allowed as equipment?

Yet I dive (tiny) sidemount. Taking a one tank class would only result in me back in two tanks the next day. Being limited to single sidemount because I gained a cavern card would be super annoying. I appreciate single tank makes more sense in back-mount, but strapping on buoyant doubles is not hard. Of course, if you get students who say they actually want to dive caverns to take cave instead, that works.

If tech level cavern goes away, you really need good cave level ITT (or tech sidemount) available and taught.

I'm sort of ok looking at going from tech sidemount (particularly a 4 day one) to Cave 1 instead of Cavern. But if all that gets compressed into just Cave 1, because teaching ITT in open water is a pain and tech cavern went away, that is a rough start. I get Florida may not have much cavern, but Mexico seems to.

Maybe rec cavern, in single, can still serve as a 'practice with some of the tools class' on a path to tec cavern (aka Cave 1). Though NSS-DCS Cavern class is an entry class, not an external appreciation class, though taught in single tank (backmount?) only, so if it silts out you’re still blind in a cave.

 

[fxb]

I'm in the 'I want good cavern as self proof of good skills' camp. And to appreciate Cenotes. Maybe with Under the Jungle or someone in Florida.

I appreciate classes shifting to reduce the risk of leaving the cavern conditions. That risk seems real. Maybe keeping cavern rec single tank keeps them an extra step back from over extending in doubles. Do cavern/cave adjacent areas limit what cavern card holders are allowed as equipment?

Yet I dive (tiny) sidemount. Taking a one tank class would only result in me back in two tanks the next day. Being limited to single sidemount because I gained a cavern card would be super annoying. I appreciate single tank makes more sense in back-mount, but strapping on buoyant doubles is not hard. Of course, if you get students who say they actually want to dive caverns to take cave instead, that works.

If tech level cavern goes away, you really need good cave level ITT (or tech sidemount) available and taught.

I'm sort of ok looking at going from tech sidemount (particularly a 4 day one) to Cave 1 instead of Cavern. But if all that gets compressed into just Cave 1, because teaching ITT in open water is a pain and tech cavern went away, that is a rough start. I get Florida may not have much cavern, but Mexico seems to.

Maybe rec cavern (appreciation but not entry), in single, can still serve as a 'practice with some of the tools class' on a path to tec cavern entry (aka Cave 1). Though NSS-DCS Cavern class is an entry class, not an external appreciation class, though taught in single tank (backmount?) only.

Unless I am mistaken, unlike Wreck there is no "recreational" Cavern course that does not not involve overhead. In fact, there is no Cavern in SDI, it is only taught under the TDI umbrella. It is still a rigorous course involving plenty of drills and line work. Even if you do take TDI Cavern on doubles or sidemount, the penetration limit is 1/6 available back gas instead of 1/3 for singles, for the same reasons as stated above.

 

[MichaelMc]

Unless I am mistaken, unlike Wreck there is no "recreational" Cavern course that does not not involve overhead. In fact, there is no Cavern in SDI, it is only taught under the TDI umbrella. It is still a rigorous course involving plenty of drills and line work. Even if you do take TDI Cavern on doubles or sidemount, the penetration limit is 1/6 available back gas instead of 1/3 for singles, for the same reasons as stated above.

Yes, the single tank cavern was sounding like wreck appreciation, but you enter the same cavern as before, just now with only one tank. I'd trimmed out my rec cavern 'appreciation but not entry'. Which makes sense one way, but not as much the other. Maybe the 'we have the gas, lets go deeper' is the more common risk than the 'oh ****, we cann't see', or at least moves the second to less deep in the cave.

 

[MrBigfins]

I'd trimmed out my rec cavern 'appreciation but not entry', as yes even the single tank seems to qualify you to the same bit of daylight penetration. The single tank cavern was sounding like wreck appreciation, but you enter the same cavern as before, just now with only one tank. Which makes sense one way, but not as much the other. Maybe the 'we have the gas, lets go deeper' is the more common risk than the 'oh ****, we cann't see', or at least makes the second less deep in the cave.

I took cavern in Florida with single tank, even with 1/3 limitations I still experienced dives from 45-60 min. With the same limitations in Mexico we did 75-100 min dives. As far as daylight restrictions, it is interpreted differently but from the NSS-CDS standpoint it was as long as you still see a qtr size bit of light visible. That allows for significant penetration (certification limits in some location) at some sites and minimal at others in Florida. The options for penetration are endless in Mexico because of the configuration of the caves, to be honest it can be alittle overwhelming in Mexico due to multiple entrances/exits, karst windows etc. It really requires a solid understanding of the map and configuration of the cave.

 

[rjack321]

Maybe rec cavern, in single, can still serve as a 'practice with some of the tools class' on a path to tec cavern (aka Cave 1). Though NSS-DCS Cavern class is an entry class, not an external appreciation class, though taught in single tank (backmount?) only, so if it silts out you’re still blind in a cave.

In FL where there are no established cavern lines in the same sense as places like Dos Ojos, there are very few established caverns where - if your stick to the daylight + 130ft total depth plus linear penetration rules - you can get into that much trouble in a single tank. Actually, if the single tank cavern people need a small gas volume to keep them honest, light monkey should sell a 130ft reel to go with the C-card limits.

In MX most of the cavern dives are actually tours with OW divers. Not independent cavern (only) certified divers.

 

[tursiops]

In MX most of the cavern dives are actually tours with OW divers. Not independent cavern (only) certified divers.

The trick is to have four certified cavern divers, and let the guide know you prefer real caverns. They can't take more than 4 per guide, so you won't have any tag-alongs.

 

[wetb4igetinthewater]

In the past I would have said cavern in a single tank was ridiculous - the cavern is just a temporarily lit cave afterall. The sun goes down, dark clouds can come up, only a tiny bit of silt or percolation can obscure what little light gets to the back etc. But history has proven that cavern in doubles just gives you a whole lot more rope to hang yourself with after class. A single tank is a much firmer enforcer of not going so far.

The "cavern tours" in MX have had some fatalities but they are almost always medical events. Overhead-wise they are some of the safest trust me dives you can do - mostly because they are so shallow so there is tons of time to solve problems even at stressed consumption rates.

Do you feel that way about going to/from the air dome in Chac Mool? Maybe because I did it when I had less that 40 dives, the time we spent in the dark seemed like a long time. If the person in the back had a problem, I'm not sure that the third person would notice, given how often newly certified divers are taken in there who often lack awareness. I was #4 and my girlfriend was #3 and she would not have noticed at all (can't complain too much, as she's the reason I got into diving) if I had a problem. That camera I got her just prior to that trip took all of her attention.

Fortunately equipment is quite reliable. But maybe it is a combination of both the instructor in me and being a new parent that I wouldn't take that risk in a single tank, for myself and students. I see it as normalization of deviance.

 

[Manatee Diver]

I went on a cavern tour with a grand total of 16 dives and diving for just over a month, I now realize how dangerous it was and I was trusting that the guide knew what he was doing. But like @rjack321 says they are reasonably safe if the guide follows the rules, though I think it would be best to have full cave guides in the front and back of the group.

Video example of one of those tours that got me hooked on caves.

 

[kensuf]

Not going to jump into the fray myself; I think both sides make good points. But I don't mind the discussion on the wisdom of guided cavern dives for OW divers. I think it's relevant to the general subject matter, plus it bumps the thread so more people see it and can give their input on my question.

I'm a little surprised there's so much support here for the idea of doing cavern in a single tank; I guess if I'd had to place a bet, I would've bet on this board leaning the other way. I'd be curious to hear more about people's reasons.

I won't issue a cavern certification to a person in doubles or sidemount anymore. If you want to take cavern in doubles, take a cave class. The temptation to go beyond the cavern zone seems to be too great for many people, this really has been a problem.