Freediving after scuba diving?

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.......

From a scuba instructor point of view:

The main reason this would be dangerous in my knowledge is that when you scuba dive you build up nitrogen in your body tissues.

That nitrogen takes time to off-gas. Usually several hours(see non-flying guidelines). You are super-saturated with nitrogen.

If you free-dive, you _still have_ that nitrogen buildup, and when you ascend rapidly from a free-dive, as free-divers do, then the sharply decreasing pressure can cause nitrogen bubbles to form as you go back to a pressure where you are super-saturated.

In essence, you're risking the same effect happening in your body as what you'll see when you open a can of coke, or bottle of champaign.

Look up Henry's Law for more information.

If I may throw in my understanding of the problem, the actual mechanism is still up for debate. Some feel that by freediving, the rapid recompression and immediate decompression of the microbubbles in the blood from scuba tends to make them cluster, potentially causing air embolism of a sort - the only case I heard of behaved like embolism in that the diver went unconscious immediately on surfacing, and died. However, others feel that the physical exertion of freediving is the culprit, similar to shaking the soda bottle. Some feel the rapid ascent of a freediver, generally 6 times faster than a scuba diver's, is the problem. Some other possibilities have been put forward here. The fast rate of freediving ascent and the physical exertion are certainly grounds for concern.

As to the bends from freediving alone, while the avant garde of the sport can get it in one breath/dive, most of the rest of us mere mortals are not likely to get that deep. However, the Taravana Syndrome is pretty well known, wherein a series of fairly deep dives with a short surface interval can indeed cause a form of the bends. As I recall, someone worked out the math and came up with this: repeated dives to 100 feet, where the surface interval is equal to the dive length, is equivalent to being at 60 feet the whole time. Enough dives over enough time eventually bent the divers. Someone freediving like this for a fairly long period then doing a deep scuba dive might trigger the bends, but while possible, this is an extreme scenario. Otherwise, freediving before scuba is generally considered safe by the major freediving and scuba agencies.

While I have heard quite a number of people state that they freedive in the period between scuba dives, every major diving agency, like PADI, DAN, AIDA, and the rest, have come out strongly against it. The people who do it anyway are betting that their nitrogen loading is low enough, that the exertion and rapid pressure changes won't be a problem, and that their freediving is shallow enough. That's Russian Roulette, and best of luck.

Ok, so we all know that freediving after scuba diving is a no-no...

How about freediving before scuba diving?

Someone on this forum once stated that their scuba instructor had taught him "Freediving and scuba diving should not be done on the same day, especially when the freedive is after the scuba dive."

So why is it bad to do it before?

Well, there is some little bit of nitrogen buildup from freediving... but I shouldn't think it would be much of a problem, just plan your dive like you're a pressure group higher and it should be fine, unless you've been doing it to the extreme(at which point you should probably have freediving tables anyway).

Speaking of buildup...

Will there be more oxygen than usual in my bloodstream after a scuba dive? Making long breathholds easier?

(Don't worry, I don't plan on freediving after a scuba dive, just holding my breath in the bathtub.)

Not really, because you metabolize the oxygen.

On the other hand there will probably be some more carbon dioxide in your system. Because it gets dissolved into tissues like every other gas.

I have hit these threads, about combining scuba and freediving, over the years, watching the discussion develop and noticing the regulars, the experts, the guys and gals with the brains here on DeeperBlue becoming more and more adamant about the rule “NO FREEDIVING AFTER SCUBA DIVING.” I searched again today, before a trip to Bonaire, wanting to see if anyone added anything to the discussion specifically about Nitrox diving. Even though I'm sure the same logic applies.

Maybe as the records get deeper and the rest of us reach a little bit deeper, even in our rec fdiving, it becomes more serious. Or maybe the warning escalates and evolves on it’s own. I say that because the fact is, before so much discussion about this topic, I think a lot of us did it, without thinking twice, and without too much trouble.

But wait, wait, wait . . . hold on, don’t go off on me . . . I agree with the way the thread leans, I don’t do it anymore, I keep freedive days and scuba diving days separate. I wanted to get that clear so you-all don’t go ballistic on me, thinking I’m thwarting your SERIOUS warnings -- I'm not.

So, what I'm about to say is a moot point, since we (no one reading this info) is ever going to freedive after scuba, not until your scuba computer has cleared, right? . . . but, I think I disagree with the statement that your breathholds will not be better after diving that all absorbed oxygen will be metabolized.

Because before I knew better, I would always try a drop or two after long scuba dives. Ya' get all that gear and crap off your back, you’re hanging there in crystal clear blue water. Maybe watching a diver or two down on a wall at 25-30m, finishing their scuba dive, and you want to go back down there in the complete freedom of freediving — right?

And on several occasions when I did, I could always make amazing freedives. Amazing for me, not anything that would even show up on a competitive scorecard — you know? But I'm talking slow, relaxed and longer than my normal freedives. And I’m comparing one freedive drop, the very first one after a scuba dive, to other freedives where I warmed up and built my times up slowly over an afternoon. Nothing scientific; not even any logged times to prove it; I just know what it felt like.

I can remember on several occasions (they are vivid in my memory), watching my dive time and thinking “wow this is amazing, what’s going on here?” And I have to say it scared me and I would not reach for a new depth, even though it felt like I might be able to. The thing of it is, I knew something was different, wrong, and it was a false since of comfort that came from some unusual physiology from just ending a long slow drifting scuba dive.

So I don’t know what it’s about: maybe higher partial pressures of oxygen absorbed over a long slow scuba dive; or maybe it’s just heightened relaxation where the scuba dive was like one big giant meditatve breath-up for the freedive; or maybe it’s about moving slower and more consciously and having a little slower heart rate and already being in the zone and feeling a little extra mammalian-dive-reflex; or maybe it’s purely psychosomatic and it’s all in my feeble brain. I’m willing to admit, the last one could be the case, because no matter what you do and how you train, the psychological part of how long you can, or should hold your breath, is still the biggest part of freediving, isn't it? — at least I think it is.

Do not freedive after scuba diving! No, it doesn’t even tempt me to try it again. I know better now.

Very, very interesting observation, although maybe not very useful in itself, unless you want to set some records after scuba diving.
Its the kind of perceptive, food for thought comment you run into on DB. Where somebody else with a lot of knowledge might see it, put it together with other knowledge and come up with something that advances the sport. I can almost hear Eric F chewing on this one right now.

Connor

I'd just like to add one thing to this discussion that I always discuss in my classes.

The no freediving after scuba diving has plenty of good reasoning behind it, and most people can see the sense in that. In my opinion the conclusion that is often reached is, freedive first then scuba dive, but that has risks as well.

Lets say you go out spearfishing for an hour or two, and then are going to scuba dive.

What letter group are you? Does your computer know how much nitrogen you have? No one has any idea how much nitrogen you have after your freediving.

When people do this they say things like yeah but I did a surface interval on the boat before I went scuba diving just to be safe. Well how long was the SI and how long were you "supposed" to sit on the boat. Who knows? I hear things like oh I just make sure my next dive is conservative. Again there is no way to make any judgment on how to change the parameters on future scuba dives based on you past freedives.

So in my opinion the best rule which I teach in class is, scuba dive and freedive on different days. Of all the rules in freediving this one causes me the most difficulty. Espcially when i'm out scuba diving the Vandenburg and I really want to freedive it, but I can't because I'm going to do a scuba dive on it.

Hi guys and gals.

DON'T EVER FREEDIVE AFTER SCUBA DIVING.

Thought i'd offer a bit of evidence; one of my best mates has just died due to this.

After 2 dives he went freediving on a shallow reef, had an air embolism and drowned.

He wasn't even deep diving, but as I'm sure as you all know pressure change is greatest near the surface, and obviously this is enough to re-release any trapped/dissolved nitrogen/gas.

DON'T DO IT AND DON'T EVER DIVE ALONE. No matter how confident you are or how shallow it is.

Sad to hear that... RIP