Snorkel In or Out?

[Bill]

Soul Deep
In all the years, I only dropped the belt twice. You can open the buckle and hold both ends in place or take it off and just carry it. Retrieving the belt becomes a challenge. You can either dive with no weight (that was difficult with a 6mm suit) or get the spare and bring two up. Better still, have your buddy do it.
I am experimenting with the exhale. If you come up fast and get one deep inhale and hold, you probably have enough O2 available for a few minutes. Judges won't buy it and safety divers won't like it, but even if you black out and exhale, you should recover before you run out of O2.
I'm also trying to work out the mechanics of shallow water blackout. It appears to me that a full exhale at 20-30 meters will increase the amount of O2 available when you reach the surface. How to prove it?
Thanks for the comments on the different instructors. I hope to have a chance to ask the Performance team about it next month.
Aloha
Bill

 

[gonetobaja]

I push my snorkel out with my tounge at the dive to prevent bubbles from comming out of the snorkel on my decent.

I read earlier in the thread that it wasnt proven that bubbles scare fish. To me I have proven that fact several times. I have scared away many fish by just a bubble comming out of my snorkel or my fins hitting together. Maybe the fish in the sea where I am are more timid.

GTB

 

[Marwan]

GTB,
I agree with you, had the same experience, i try to train myself to push out the snorkel as a matter of reflex, it also somhow increases my bottom time a bit.

 

[Mr. X]

It appears to me that a full exhale at 20-30 meters will increase the amount of O2 available when you reach the surface.

Isn't that rather dangerous. I thought you were not supposed to breath out while freediving deep -- not sure why, maybe risk of collapsing your lungs (and SBA I suppose).

 

[Mr. X]

When diving in very shallow water, 2-6m, i normally take the snorkel out, as mentioned previously, the bubbles that the air makes as it escapes from your snorkel scares flighty fish.

... AFTER taking a freediving course, i learnt the displacement method of clearing your snorkel. All this entails is you looking up (when ascending, when you're about a meter from the surface) and gently exhaling a SMALL amount of air into your snorkel. This will displace the water and upon surfacing, you won't need to clear your snorkel.

The MAIN reason for NOT spitting your snorkel is that SHOULD you black out, which normally happens close to the surface, you will still be able to breathe. ...

Boy am I confused now! I always keep the snorkel in but after a similar discussion on another thread recently, I came to the conclusion that I should keep the snorkel in on shallow dives & take it out on longer/deeper dives. So I started practising taking the snorkel out -- but it really seems to mess up the flow of things for me currently.

Now Miles has made me think again! :duh Not sure what to do about shallow dives -- seems like views vary here, I guess both have pros & cons. Miles does shoot an awful lot of real big fish though! :hmm I read about displacement clearing in the other thread -- and tried it with moderate success. The idea about looking up while doing it is new to me though, I will definitely have to give that a try (it should make judging the correct point to blow out easier too). Thanks for that .

 

[Bill]

I spoke out of context. Sorry. Better to say....
On a 60+ meter dive of 2+ minutes, a full exhale 15-20 seconds before surfacing may result in more O2 in the blood to prevent blackout.
At 30 meters, for me, a full exhale will only reduce my total air (measured on the surface) 10-15%. I have begun exhaling a little deeper and don't notice any difference yet. Buoyancy change may be a limiting factor.
Aloha
Bill

 

[donmoore]

Bill,
I haven’t been able to do the amount of rope diving you have or the depth, but I was having trouble with samba’s from both dry and wet statics. In the dry statics I was watching a pulse/oximeter and had a good idea of what my SaO2 was. I started exhaling further and breathing harder and the samba’s became worst. Then I e-mail Kirk Krack and ask him what I was doing wrong. He said I should not fully exhale and take quick upper lung breaths to maintain my blood pressure. He said a full exhale could drop blood pressure which would decrease the amount of O2 to the brain.

I changed my recovery breaths and it made a world of difference. Same SaO2 readings that before had caused samba’s were now no problem.

I understand your idea of fully exhaling the air out of lungs to avoid the sucking of O2 out effect associated with SWB, but I worry about the loss of blood pressure. I also understand the hook breath principle to increase the blood pressure and push O2 from the lungs into the blood stream. But my worry is that how every you take your first breath it’s going to take 10 –20 seconds before that O2 reaches the brain. Therefore you are forced to live with the O2 in blood on route to the brain until the first breath O2 makes it there. So to me it really isn’t how much O2 you can cram into your blood on the first few breaths, because any amount is going to be more than what you currently have, but maintaining consciousness through the first 10 –20 seconds.

I just wonder if there isn’t a happy medium of exhaling toward the surface, but still maintaining enough air in the lungs to keep from dropping the blood pressure? I don’t know how much of a drop in blood pressure a full exhale gives someone, but I do know that changing from full exhales made a difference in my static recoveries.
don

 

[greendiver]

I have been diving for some time now, however I seriously started not so long ago, and the first thing I noticed, especially in shallow water, how the bigger sargos, would "fire" away...like roadrunners........, nobody told me, but the snorkel out!

 

[Bill]

'Therefore you are forced to live with the O2 in blood on route to the brain until the first breath O2 makes it there. So to me it really isn’t how much O2 you can cram into your blood on the first few breaths, because any amount is going to be more than what you currently have, but maintaining consciousness through the first 10 –20 seconds.'

No arguement, with you or Kirk. I'm working on the model of the dive. One possibility has me at 30 meters with blood saturation that will allow me to get to the surface with 20 seconds of O2 left if I can prevent the reverse transfer. Total prevention isn't possible but, if you were to assume on a max dive that lung O2 is 2 1/2%(by volume) at 30 meters and 5+ at the surface (or you would black out), then about 6% of the total O2 that you started the dive with will transfer from the blood to the lungs in the last 30 meters. Still working on it.
Aloha
Bill

 

[Soul Deep]

Bill, your work sounds interesting. Would you mind explaining in laymen terms what you mean about the basic theories of the dive model and what you mean by reverse transfer etc? Also how this then relates to best time to exhale with a snorkel on a dive

Cheers...

 

[Bill]

It's something like this.......
Start dive with 100% available O2, fully saturated blood and 20% in lungs.
End dive (sfc +5-10") with zero available O2, 50% saturated blood and 5% O2 in lungs. Assuming a max dive, anything less would result in a blackout. At this point blood saturation 'tracks' lung O2 with some delay.
Back down to -30 meters on my 60 meter dive, assume 15% of available O2 is used from there to sfc +5 and the numbers might look like....
blood saturation 70 and lung O2 2% by volume PPO2 8%. This assumes a lot of things, some of which must be false but, basically that blood O2 saturation tracks lung partial pressure from 15 to 5.
Now we see the SWB theory, O2 must transfer from the blood to bring the lung volume up to 5%. If we could stop this transfer, it would be the same as having 10% more O2 for the dive. Not possible of course but, if we exhaled to and maintained residual volume, starting at 30, it might be halved, offset by an unknown amount of increased work for lack of buoyancy.
Without instruments I can't find out except by trying. So far I haven't been able to confirm anything. I have tried a full exhale at 12 meters and plan to work deeper but, I keep forgetting to warn the safety divers.
Does that all sound like goobledy-goop?
Aloha
Bill

 

[Mr. X]

Don't forget to fill in the snorkel in/out survey for *spearfishing*:
[ame="http://forums.deeperblue.net/showthread.php?t=63661"]Snorkel In/Out Survey[/ame]

 

[Queer4spear]

Snorkel out....always....... Too noisy

 

[greendiver]

I have seen people taking them out and putting them behind their weight belts, tried that as well, last 3 snorkles.. :duh

 

[freediver7]

Removing the Snorkel before I descend helps me relax. This also cuts down on the blub blub noise of air escaping from the tub as you descend.

 

[greendiver]

Removing the Snorkel before I descend helps me relax. This also cuts down on the blub blub noise of air escaping from the tub as you descend.

...Good idea, never thought about it this way....focus on the breathing...the right moment....thanks!!

 

[flyflicker]

I was absolutely captivated by Tanya Streeter and her swimming with whales in the recent TV documentary.

But I’m sure it shows her surfacing with her snorkel most defiantly still “in” - does this make it right or is it just a TV editing fault??

 

[Mr. X]

I was absolutely captivated by Tanya Streeter and her swimming with whales in the recent TV documentary.

But I’m sure it shows her surfacing with her snorkel most defiantly still “in” - does this make it right or is it just a TV editing fault??

If Tanya :wave does it, it must be right! I see from these forums that she does spearfish -- presumably she didn't do that on the TV program? [She probably has a lot more puff available than those of us that are not professional apneaists though!]

 

[jimdoe2you]

Now hold on a minute.........................my theory is that Tanya, through her affiliation with Kirk Krack, would cater to the snorkel out discipline, but if she is doing shallow dives (less than 6M) it is not unreasonable to keep the snorkel in thoughout your diving.

 

[flyflicker]

Jim

That is most probably the answer, the TV clip only starts as she surfaces, so there is no gauge to how deep she’s been -- I thought it would be something along those lines- thanks for clearing this one up. Now back to work.. 