Freediving after scuba diving?

[Angus]

Cliff, I appreciate you articulating the bigger picture. Our decisions effect more than ourselves and that needed to be factored into this. Your point about us needing to be responsible and that our level of responsibility can affect the level of how others may respond to us is also valuable. The number of times I have walked away from people doing foolish things - things they knew were foolish and dangerous is numerous. We are not the keeper of others and they have the right to screw up. They don't have the right to screw up and put others at risk however. Thanks, Angus

[Sickboy]

Cliff, thanks again for your reply, and for emphasising how horrible DCS is, not only for the sufferer, but also fro those around him/her. It is not something to mess around with.

I'm not trying to say you're wrong, I just want clarification on this subject. As far as I can see, it is ok to mix free diving with scuba IF you freedive BEFORE you scuba, and not after.

For recreational freedivers (say, max depth 100ft/30m), I cannot see nitrogen loading being that much of a problem as to increase the risk of DCS on later scuba dives, especially if you keep a safety margin from your NDLs. The nitrogen loading during the freediveing should be minimal. Perhaps if one spent more than 3 hours freediving, it would be harder to tell. In a way it's like drink driving. It's ok to drive and then drink, but not to drink and then drive.

Does this sound logical? Or am I missing something?

Regarding diving after a flight, I read somewhere that because aircraft cabins have a lower pressure than sea level during flights, your body will actually have a *lower* level of Nitrogen after the flight, which should resuce the risk fo underserved DCS if you follow a normal dive plan.

Of course this only relates to nitrogen loading and DCS. Are there any other problems that could arise from diving after having been in a low-pressure enviroment?

Terry

[Sickboy]

Angus, I'm glad you are finding this discussion useful. I am sure this is a very common occurence, mixing freediving (or snorkelling) with scuba, and yet I have searched the net and have found very little information directly related to it.

A friend of mine went to the Maldives for a scuba trip some time ago, and after a few days he displayed the symptoms of DCS, and had to go into the chamber for treatment. He made a full recovery fortunately, and is diving again now.

He was scuba diving with a computer, and was not doing decompression dives. But the problem was he was snorkelling between the scuba dives, and it turns out he was going pretty deep (around 20m I think), and so this seems to be the most likely cause of his DCS.

Soon after this I was in the Philippines to do my Advanced Open Water, and I specifically asked my instructor if there is a limit to how deep I should snorkel to if I have been scuba diving. He and another instructor in the room both replied "no, just make sure you have enough air to get back to the surface!".

On another scuba trip I was talking to an instructor and asked if he ever freedived. He said he loves it, but since he takes divers out every day, he can't freedive because he needs to give himself 24 hour to clear his scuba nitrogen.

On my most recent trip, I again asked the instructor if he freedived. He said he did and he had the fins and all. He said him and a few other instructors used to take a bunch of weight belts on a rope and drop down to 30m, then swim back up. He said he didn't do it anymore, and I asked if it was because he scuba dived every day. He said it wasn't because of that, it was because it was too tiring and he was too lazy.

It was this crazy inconsistency in peoples' attitudes that got me a bit worried, and got me looking into this matter. The fact that scuba instructors (of all people) could have such different perceptions on such a dangerous phenomenon just highlights the lack of knowledge we have about DCS, and even more so when mixing in freediving.

Obviously this risk pertains mainly to freedivers, since scuba divers who are not into freediving would only snorkel to depths that would not present much risk (less than 5m probably). That's why I'm glad we have this site and forum to discuss such matters, to try and prevent any accidents that may occur due to ignorance.

All the best,

Terry

[freediver48]

Hey Sickboy,

You are right on with your last statement, it sure is great to be able to communicate together. While we may not all agree on issues of risk management, and the like it sure is a great and illuminating hit, to visit Deeper Blue. By the way I p[osted your question on FDL and it got thumbes down, e.g.

"I would follow Terry Mass's recommendation. If these computers could follow and track your gas loading is not the issue. It really comes down to bubble physics. The worst thing you can do is freedive after scuba, whether it is deco diving or no-deco diving. To make a long story short, very short.

what happens is the micro bubbles that you get after any scuba dive grow as you come up, your lungs off gas these. unless you have a PFO the bubbles should stay on the veinous side and be eliminated by the lungs. if you compress them again, by diving, these growing bubbles and can compress and bypass the lungs and move over to the arterial side, this is bad. now as we
can not stay down very long we do not give our body time to handle this. as we start coming up these bubbles are growing on the wrong side of our lungs, the arterial side. so instead of using our lungs to filter them out we will now use things like our brain and other parts of our body we have grown to like. this can lead to a real bad hit.

This was the very short answer. If you need a longer one give a yell. If you must combine them, freedive before scuba only. Never between or after. But the best bet is to follow Terrys advise, do not combine them."

Alan Pelstring
S. Fl.

Will Rogers once said:
"If God didn't have a sense of humor, he wouldn't have made monkeys and some
people." Best wishes, FD48

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[Peter Sheard]

In a previous thread there was a brief reference to a relevant article in Freediver Magazine.

The complete reference follows:

Sheard, Peter (2001) A dangerous mix – SCUBA and freediving. Freediver 13: 18 - 19. ISSN 1466-089X

The article will be re-issued, by permission, on Deeper Blue sometime in September(?)

In the meantime, the DAN statement that there is not enough specific research to draw accurate conclusions is 'true' but slightly misleading -- there are some logical conclusions (from related research and basical physical processes) to be drawn that the combination is risky.

The risks lie not in added nitrogen but in 'migrating bubbles.'

Subscribe to Freediver Mag and find out more . . .

Pete

[Stephan Whelan]

Just so everyone knows - you can subscribe to Freediver (the UK magazine Peter was talking about) by going to their website...

http://www.freediver.co.uk

[ISleepUndrwater]

Well..... as long as we are combining things:

How about carying a dive sled with you and jumping out of a plane at 45,000 feet?
Well, you gonna need compressed gas for a minute at least...
Probably a good idea to mix it with helium instead of nitro
(no silly, it wont make you fall slower)
HALO jump - High altitude Low Opening - would be best.......
if ya really want to risk the bends..... dont open untill the last few hundred feet.
Cut loose from your chute about 15 feet above the water and drop in with the sled. That extra speed will send you down faster.
You dont want to be hooked when it fills up with a few tons of water... sure it will pull you down faster....but will trap you too,
awwwww heck....... I almost forgot.... we were TRYING to be dangerous.. maybe chum the waters too.. makes for better
pictures. plus it will be a bigger hit on the news....
"Skydiver gets the bends, Great White gets tasty treat"
anyway....
I dont condone mixing activities either.....
But I get this icky feeling someone is gonna try my idea and live.
And then Ill be sorry I didnt get credit for it.......