DPV gas planning

[RN]

How do you plan?

I'm pretty conservative and always plan to be able to swim out even when I'm towing a 2nd scooter. I've had some wonky things happen with scooters and other mechanical equipment that I just don't trust them enough, especially when it comes to my life. I know not everyone is this conservative. In fact, I've heard some gas plan the same whether they're doing a swim dive or a scooter dive.

So what do you do? And why?

[Superlyte27]

I plan on CCR dying, buddy not noticing, scooter crapping out.... aka, enough gas to swim out at max penetration.

[Danseur]

Always plan to survive the worst possible day of your life...

[Sludge]

I always scooter with untouched backgas. One stage will get me, for example, p4,000' and back at JB. For anything more, I take another stage.

[Dsix36]

In a team of 3 divers on CCR and scooters, I plan for one CCR failure and one scooter failure.

If the dive is big enough to need to plan for team bailout rather than being self sufficient, then some serious predive planning takes place and methods are practiced before the dive at hand.

[bamafan]

I was taught plan for any two failures if you have three it is your day to go.

[PfcAJ]

Depends on the dive and it depends on the cave.

Sometimes enough gas to swim out. Sometimes enough scooters so that I won't have to swim out.

IMO, planning to swim out on a deep cave dive is not realistic. The deco times and gas requirements become absolutely bananas rather quickly. I always tow on deeper cave dives, and often on shallow ones too.

I also dive with pretty good buddies, which factors in a bit. So realistically we'd have to lose a pile of scooters to end up swimming.

[RN]

Depends on the dive and it depends on the cave.

Sometimes enough gas to swim out. Sometimes enough scooters so that I won't have to swim out.

IMO, planning to swim out on a deep cave dive is not realistic. The deco times and gas requirements become absolutely bananas rather quickly. I always tow on deeper cave dives, and often on shallow ones too.

I also dive with pretty good buddies, which factors in a bit. So realistically we'd have to lose a pile of scooters to end up swimming.

It does depend on the dive and cave. I'm not referring to something like Eagle's Nest here. It's simply physically impossible to carry enough gas to swim out of there after scootering in or to deco on bottom gas if you lose a gas. That's an entirely different thing.

I'm referring to basic cave dives in the 80-100' depth range. While having multiple scooter failures is not likely I have heard of it happening. And I have heard of having to swim out from significant distance because of this. IMO that was just poor planning. While bigger dives require some risk assessment and deciding what is okay to do and not to do, for most scooter dives planning for a swim exit isn't all that difficult. I know I can swim out from Stage Rock in JB (2600 p) on a single AL80 and still have gas left over. I've done it to prove the math works. And I even pushed myself a little bit and was pushing the scooter ahead of me to try to get my RMV up to simulate a stressed situation. (See Kelly's post #9). So for me a couple of AL80s will get me out from pretty much anywhere in the mapped passage of JB. I might have a bunch of deco but I'd rather have to ride a chamber than not make it out at all.

[steve2281]

I still plan it the way you taught me in DPV class. Assuming a two man team with at least one diver in backmounted doubles, one scooter for each diver: plan gas to be able to swim out with one total loss of backgas and 2 scooter failures at max penetration.

[Kelly Jessop]

The only thing I hate to see is gas planning based on math exclusively versus some real testing. So many people will say I can exit from the Heinkel on an AL80 stage because I have a SAC of X, swim rate of X, flow rate of X..... my calculations show I have a enough gas. There are so many variables that I found when I simulated swims like this from different systems that I found that my mathematical planning would have left me short of a safe exit.