Deco on the fly stops

[Mr Garic]

When you use the deco on the fly method do you make stops well within the cave system? I know that technique requires more deeper stops. What's standard operating procedure?

[Data]

this must be a trick question.
are you from the dir diving police and check if anyone falls for it?
I could tell you, but then I'd have to kill you.
you have to get the secret hand shake first.
these are the usual replies to your question, but I just send you a nice pdf that explains it all.
you can now read it, ignore anything what ever anybody else says that you should actually take a class with a knowledgeable instructor and go and kill yourself.

[Dave]

No, with Deco on the Fly, you cannot make your stops within the cave, they all must be done outside the cave.
I usually make a stop at Edds, another at Burger King in Dothan, a gas stop in Eufaula and a safety stop in Columbus.

Dave

[Cave Ranger]

Hmmm. This gives me an idea.
I wonder if Ginnie would allow me to put an Air Bell just inside the entrance of Devil's Ear or at the Ear/Eye junction. I could open the worlds first underwater Donut/Coffee/Taco/Beer joint that could serve as the last Deco stop. I still have some design issues to figure out and the logistics on how to keep the Dancing girls from catching cold keeps coming up at the meetings.

[FW]

When you use the deco on the fly method do you make stops well within the cave system? I know that technique requires more deeper stops. What's standard operating procedure?

While I share Data's confusion...

You stop where you have to. As Dave so "nicely" put it, you can't always wait until you are out of the cave. Sometimes, if you get lucky, deep stops can be done as you swim, but only if the passage is at the correct depth for a long enough distance. Usually you end up stopping in a vertical passage.

[Mr Garic]

When you use the deco on the fly method do you make stops well within the cave system? I know that technique requires more deeper stops. What's standard operating procedure?

While I share Data's confusion...

You stop where you have to. As Dave so "nicely" put it, you can't always wait until you are out of the cave. Sometimes, if you get lucky, deep stops can be done as you swim, but only if the passage is at the correct depth for a long enough distance. Usually you end up stopping in a vertical passage.

Doesn't that get you into a situation where you need more than one third of your starting gas volume for exit?
That's all I don't get.
I guess I should have phrased it better in the first place.

[skip]

usually the exit takes much less than 1/3 of the gas supply. one-third in, turn the dive, and it takes 1/4 out (or less)....so you can do the deco on the backgas and still be safe. if in doubt, low flow, no flow, siphon, you would either carry deco gas staged or turn the dive on 1/4 or even 1/6. plan the dive, dive the plan.....


not that i'm an expert or anything, but it's worked for me! I usually do deep stops whether required or not, but then they are usually real stops (at bottom of vertical passage), not on the fly. obviously everyone does "deep stops" on the fly if enough horizontal passage....

-skip

[FW]

Skip is right, just plan to have enough gas for deco. You should be doing that anyway

[aw]

Most deeper stops on a normal cave dive are no more than a minute or so each 10 ft. So the gas used is usually negligible. And really the deeper stops on normal dives are just to force you to slow your ascent rate. So under NORMAL conditions, I would not adjust my gas plan.

For advanced dives like trimix, you're gonna have an intermediate depth gas and 100% gasses to switch to. And these dives would be outside the realm of "deco on the fly" anyway. In cases where you will be stopping before reaching your intermediate gas, then yes, you would adjust your gas plan slightly to account for this.

Like FW said, it depends on the cave characteristics. I've dove Hendley's Castle on trimix where I did a short "deco" stop once or twice on the way back up that jump and I was still 1,300 ft from the entrance. If you were to do a trimix dive to the bottom of Aphasia Pit in Harvey's, you'll be doing a few required deco stops before you get back to the main passage, and you are still 400 ft from the entrance.

[aainslie]

Last time I was at Ginnie my first deco stop was before the lips, second by the sign in the ear. I accidentally blew through my third stop halfway up the eye and had to scurry back down. The VR3 can really leave you with quite a few deep stops! We'd racked up over 1/2 hour of deco on a 100 minute dive. About 10 minutes of this was before the O2 stop.

That said, I had two almost half-full stage cylinders and almost half my back-gas (or side-gas!!) in reserve. Gas is definitely not an issue in high flow caves like Ginnie, even if there's an air share on exit. And if I had reserved, it would have been something like 100 psi on backgas - you're resting, after a nice long slow swim with the current, and your SAC is just about as close to zero as it'll ever get.