Discussion of best practices for advancing in cave diving (moved from A&I JB thread)

[cerich]

losing 4 stages (2 each) is not going to happen.

that is one bold statement

 

[Manatee Diver]

I wasn't really planning to start a discussion on stage planning, but to explain why dropping stages is ok, but taking of a "back gas" SM tank isn't. And even then you're trained specifically on how to plan for it and in case of a loss.

While at no point in a full cave or tech SM course are you taught equipment removal. That is a separate course to be done after someone is an experienced cave diver.

I don't know about anyone else at three years about 150 cave dives, and almost to my Abe Davis I don't think I am ready for Advanced SM. Heck I am still a little nervous for Cave DPV this winter, even though I know it will become an indispensable tool for my video work.

 

[PEDiver]

I don't know about anyone else at three years about 150 cave dives, and almost to my Abe Davis I don't think I am ready for Advanced SM. Heck I am still a little nervous for Cave DPV this winter, even though I know it will become an indispensable tool for my video work.

Cave diving is, IMO, something that should never be rushed. I look at diving like a chain: the first link is your OW and the last link is where you want to end up (say, for example, cave CCR). Each link after and preceding are necessary. If you rush, or cut corners, you end up with weak links or a broken chain. Once you are proficient and comfortable, you move to the next link in the chain. I personally came to this conclusion a while back when I realized I was moving too fast and needed to slow down. Too many people around me were already moving to DPV and CCR and I succumbed to the pressure. Ultimately, I sold my CCR and took a pause on DPV. Absolutely nothing wrong with going slow and being safe.

 

[Manatee Diver]

Too many people around me were already moving to DPV and CCR and I succumbed to the pressure.

I lost my last regular buddies I was diving with to CCR and DPVs. But I march to the beat of my own drum...

 

[PEDiver]

I lost my last regular buddies I was diving with to CCR and DPVs. But I march to the beat of my own drum...

That's unfortunate, but you may be better off in the end. The trend seems to be people moving to CCR without any real need for one. I'm a firm believer in exhausting the limits of OC before moving to CCR for longer/deeper dives. I've noticed that most serious cave divers march to their own drum anyway...

 

[Manatee Diver]

I've noticed that most serious cave divers march to their own drum anyway...

Part of the reason why cave politics is almost a combat sport.

 

[L13]

Thirds on stages doesn’t make a lot of sense.

That gas cannot be shared (one hose) ...

What happened to classic buddy breathing?

But the rest still makes sense:

... and when you get back to the next stage, you have a scrap of gas left in the previous one about 1000psi). If things are going sideways, you now have a bundle of stages, each with just a little bit of gas in them.

Half’s on stages and reserving the balance into your backgas allows that reserve to be shared and you keep it with you the entire dive. You’re either on the stage or it’s empty on the way out so you have full access to all the gas in the water but can ditch the empties along the way out so you move faster.

 

[lermontov]

Thirds on stages doesn’t make a lot of sense.

That gas cannot be shared (one hose), and when you get back to the next stage, you have a scrap of gas left in the previous one about 1000psi). If things are going sideways, you now have a bundle of stages, each with just a little bit of gas in them.

Half’s on stages and reserving the balance into your backgas allows that reserve to be shared and you keep it with you the entire dive. You’re either on the stage or it’s empty on the way out so you have full access to all the gas in the water but can ditch the empties along the way out so you move faster

whether its thirds or halves the same applies you cant share easily with one hose and you still have the reserve on your back if its thirds or halves -the only advantage for halves I can see is the efficiency of gas transportation. The upside of thirds is presumably your stages are closer together so you have less distance to cover a meltdown and you always closer to new gas

 

[nakatomi]

What happened to classic buddy breathing?

It simple won't work in a cave, at least most of the time it won't.
There's usually not enough room to swim side by side, buddy breathing is also completely incompatible with scootering.
And generally when you're low on gas, you'll want to take a sharp exit, not waste time playing ping pong with a regulator.

 

[PEDiver]

The upside of thirds is presumably your stages are closer together so you have less distance to cover a meltdown and you always closer to new gas

The stages may be closer together using thirds, but you still have a lot of gas tied up in those stages and carrying multiple stages with 1000psi will only increase drag and make the exit slower. In addition, you sometimes can't always drop stages as soon as you hit thirds so you're carrying that bottle further anyway to find a drop point. It's much easier to use half+200 since you're reserving some of that gas in your backgas and can shed those stages faster, meaning you're reducing drag and you have that gas on your back (and those tanks aren't going anywhere).