First Dive Trip Without Instructor - Need to Rent Gear & Help Planning

[Lorenzoid]

In the TDI cavern standards it states using a rule of 1/3 for a single tank but 1/6 for doubles. I dive back doubles pretty much exclusively. Can you explain the extra conservatism for doubles over a single tank?

So you don't penetrate much further than you would have if you had a single tank?

 

[Marie13]

I got carried away with how awesome it was and lost situational awareness.

Wow. You got lucky.

 

[PfcAJ]

In the TDI cavern standards it states using a rule of 1/3 for a single tank but 1/6 for doubles. I dive back doubles pretty much exclusively. Can you explain the extra conservatism for doubles over a single tank?

The guideline is really about limiting distance from the entrance. Generally the close you are to the big air tank in the sky the better.

That said, I can’t support diving in a cave with a single tank. Too many eggs in one basket.

 

[halocline]

Max depth in that room was in the 90s.

Yes I know we went further than we should have. Edd also admonished me. I’m signed up for intro to cave with Edd in August. Will be practicing basics till then!

Please don't take this the wrong way, but you have ZERO open water dives past certification, and you're talking about cave training? Wow....not to mention that your on your first post certification dives, you violated the level of your cavern training and ventured far into the cave zone.

It's not my intention to embarrass you, and I admire your enthusiasm, but you clearly do not have anywhere near an appropriate level of respect for the dangers of cave diving. Get some dive experience in open water, I don't know, maybe at least 100 dives, then consider your cave class.

 

[halocline]

In the TDI cavern standards it states using a rule of 1/3 for a single tank but 1/6 for doubles. I dive back doubles pretty much exclusively. Can you explain the extra conservatism for doubles over a single tank?

It's similar to the Intro to cave level penetration. The idea is to limit total penetration so that less trained cave divers simply don't get too far back in the system. Its approximately 26 cft of gas (assuming AL80s). It's not a perfect rule by any means; someone could take, for example, a 120 on a single tank with a H valve, and use 40 cft on the penetration. In a shallow cave like in MX, that could easily be an hour back, then you're left with a not-fully trained diver who only has 80 cft in a single tank to make an hour long return, with the responsibility of sharing air if necessary. Does that sound like a good situation?

 

[boulderjohn]

Get some dive experience in open water, I don't know, maybe at least 100 dives, then consider your cave class.

I sent the OP a PM that said that and more. IMO, you will have your best experience with some technical training before starting cave training. You should be comfortable using doubles, maintaining trim, frog kicking, etc. before you start that training. Cave training is for cave training, and that is where you want the focus to be. The other stuff should already be in your skill set.

 

[halocline]

So you don't penetrate much further than you would have if you had a single tank?

Yep, you don't penetrate any further (assuming the same size tanks). It's not a rule about gas planning, it's about staying away from getting far back into the cave until you've completed full.

Personally, I think they should just abandon the use of single tanks in overhead training.

 

[GlennL]

I get the additional rule about gas planning as an additional effort to limit penetration. But, as a cavern dive you should also be able to see daylight/the entrance. Is it really necessary to include gas management as part of additional rules. We are all adults. Abide by the first rule. We don’t need backup rules to ensure other rules are followed.

In regards to dive count in relation to courses. I agree and disagree at the same time. The assumption is dive count equals time that correlates to experience. But, all experience is not necessarily good. Furthermore time does not equate to ability. I’m not against requiring a certain amount of dives, simply because there are additional mental aspects in addition to pure skill. Dive count in and of itself does not make a good diver. It’s the quality of the experience.

I’m definitely no expert. But the training agencies seemingly have not put much stock in dive count in correlation to cavern training. From what I have looked at, PADI doesn’t dictate any dive count. Just having advanced open water (which is a joke), and TDI only wants 25 dives. So if a training agency doesn’t dictate a high amount of dives for cavern training, should individual diver opinions supersede that?
Also, why have a 100 dive minimum for solo certs but a lesser requirement for cavern????

 

[tbone1004]

@GlennL because cavern diving has always been looked at as a recreational cert, and solo is technical. TDI has cavern instead of SDI because it's overhead, but even in the "Cave only" agencies like the CDS and NACD, it's always been looked at as a recreational cert which is why the "cave gear" isn't required at that level, particularly the redundant regulators.

 

[kotik]

Edd gave me a talking to both in person and email. I’m honored that he is offering intro cave training to me and my buddy in August.

Careful- if you mention training with Edd three times in front of a mirror, bamafan will appear behind you.