New safety protocol? loosen weight belt AND remove mask?

[efattah]

Having had many dives with sambas and several blackouts, including one samba on a recreational dive in 2002, I can say first hand what happens in these situations.

Even for someone with great experience with hypoxia, you will never realize that you are in trouble until you reach a shallow depth. If you really overdid it, you may realize you are in trouble at a depth of around 15m, but usually you'll realize it around 10m or less. Once you realize that you are in trouble, you have about 1 second of useful consciousness, which is not enough to do any task. Once that one second elapses, the only thing you will do is continue kicking towards the surface, in a virtually unconscious state.

Even if taking the mask off had an oxygen saving effect, this oxygen saving effect would have be IN EFFECT for at least 10-20 seconds of dive time to actually have a noticeably positive effect. But, you need to SUBTRACT the energy of actually removing the mask (and holding it hard clenched in one hand, which is what you would likely do). Not to mention the total loss of velocity caused by the drag of doing it. In my opinion it would be detrimental.

I did a 'dumb' solo freedive in 1998 to 31m with a big weight belt and bifins. On the ascent, I realized I was in trouble around 15m, and my last clear thought was 'I should ditch my weight belt.' The next thing I knew, I was at the surface and my vision was gradually returning. I was still wearing the weight belt.

By 2002, I was much smarter. After having already set a WR and having had blackouts at the end of dives, I realized what I should really be thinking when in trouble. I did a shallow dive on a wreck (23m) for a very short total dive time (1'30"), but my recovery had been far too short from the previous dive. On the ascent I suddenly realized I was in trouble around 15m. I knew I had one second of useful consciousness. I used that one second to tell myself one thing: Remember to breathe upon surfacing!! I reached the surface in a virtually unconscious state, but I took a deep breath, and had a big samba. My buddy was 30m away pointing in a different direction. If I had tried to ditch my weight belt, I would probably be dead.

In my mind, the only time it is conceivable to ditch the weight belt with benefit (or remove the mask), would be if you got stuck in something on the bottom (wreck, fishing line, etc.), and you overstayed your bottom time and realized you had been on the bottom for WAY too long. Even before beginning the ascent, you decide that you must ditch your belt and remove your mask. You don't lose any momentum or cause any drag, because you aren't even moving yet.

[laminar]

Practicing mask removal over and over again may lead to a reduced "life-saving" effect. Seb Murat might have some insight on this. If it starts out being a stressful event, long practice would tend to make it comfortable. Seb experienced this desensitization effect during his high-stress training program.

Overall, I really don't know how practical removing your mask is on the way up. The loss of vision, inability to judge how close to the surface you are, panic, feeling of drowning and having water in your nose/sinuses (possible sucked in my involuntary contractions), inability to see obstacles to your surfacing, makes for a messy surfacing. There is also value in having your nose airway sealed off from the water should you black out on the surface. Ideally, your buddy sees you in time and can assist you even if you loss consciousness on the surface. If your nose is exposed, water is more likely to jeopardize the airway before and after consciousness is regained.

I could see the O2 saving benefits of removing the mask (if all other stress factors didn't counter them) on a deep line dive near max.

Better yet, dive without a mask in the first place from start to finish (or use fluid goggles).

I think the best way to prepare for a hard dive is to practice on a line. But then again, practicing on a line means you are perhaps more likely to go deeper than you should recreationally. Personally, I prefer baby steps in recreational diving, ending dives before contractions (once you are knowledgeable about your own physiology and your personal symptoms of overbreathing), and not diving by the gauge/watch.

[Fondueset]

Since I finally sold my soul and got something less than an F1, I've been pleased how useful a guage is. I use it for basically two things - reviewing my dives when I'm done - and enforcing decent surface intervals.

(my daughter PREFERS to dive with no wetsuit and no mask - just a monofin. once the temp is about 16c the suit is gone)

[trux]

Waiting till you feel you are in troubles, is of course nonsense. You have to do some countermeasures far before. That's exactly why I am telling I am opening my belt buckle at any dive longer than some 40s. And I do it preventively at the bottom, I do not wait to see if I can make it up first.

I realize that removing the mask is less practical, but you could probably drill yourself for doing it when starting the ascent too. Once you are used doing it regularly, it won't be too inconvenient. Finally when ascending, the vision without a mask should be rather sufficient. Better than removing and keeping in the hand is probably pulling it down to the neck, or maybe keeping on the front - some additional fixation might be wise though, to avoid losing it.

[naiad]

I am not too sure about the whole dive reflex thing. For me, cold water on my face, or being in cool water, reduces my apnea time and increases the risk of blackout. I am not sure why this is, but it has consistently proven to be the case for me.

[trux]

Originally Posted by naiad

I am not too sure about the whole dive reflex thing. For me, cold water on my face, or being in cool water, reduces my apnea time and increases the risk of blackout. I am not sure why this is, but it has consistently proven to be the case for me.

The only explanation is that you are a cold-blood reptile, not a mammalian, Lucia

[naiad]

Maybe not too far from the truth...
http://forums.deeperblue.net/beach-b...tml#post629467
http://forums.deeperblue.net/beach-b...tml#post629972

[efattah]

Originally Posted by naiad

I am not too sure about the whole dive reflex thing. For me, cold water on my face, or being in cool water, reduces my apnea time and increases the risk of blackout. I am not sure why this is, but it has consistently proven to be the case for me.

< this post is a friendly JOKE >

The only explanation is that Naiad is a cold-blooded liar....!

[harbour seal]

thanks for giving your insight eric. having only a 1 sec window is not sufficient time to do much of anything. i think your mantra of "remember to breath upon surfacing" is optimal given the situation.

Originally Posted by efattah

In my mind, the only time it is conceivable to ditch the weight belt with benefit (or remove the mask), would be if you got stuck in something on the bottom (wreck, fishing line, etc.), and you overstayed your bottom time and realized you had been on the bottom for WAY too long. Even before beginning the ascent, you decide that you must ditch your belt and remove your mask. You don't lose any momentum or cause any drag, because you aren't even moving yet.

i am glad you mentioned this type of scenario as it is exactly the type where i think these techniques would be most effective.

specifically, ted's (unirdna) account of his BO while diving with connor and his son came to mind. basically he ended up staying much too long on the bottom at depth before suddenly realizing he had to get going (probably CO2 narced?). in a situation like this dropping your weight belt and mask would seem to make sense.

http://forums.deeperblue.net/freediving-stories/50858-lessons-learned-bahamas-intimate-account-our-most-dangerous-enemy.html

Originally Posted by trux

You have to do some countermeasures far before. That's exactly why I am telling I am opening my belt buckle at any dive longer than some 40s. And I do it preventively at the bottom, I do not wait to see if I can make it up first.

this seems the most realistic approach (loosening it upon commencing ascent), given an operating window of 1 second, in which weight belt removal would be possible.

in fact, the beginning of the ascent seems the only time that either of these techniques would be both useful and possible.

Originally Posted by trusx

Better than removing and keeping in the hand is probably pulling it down to the neck, or maybe keeping on the front - some additional fixation might be wise though, to avoid losing it.

as eric mentioned drag created by holding the mask would be an issue, particularly if you held it by the strap. although i think less so if you held the body of the mask.

with practice, would it be possibly to easily slip the mask down below the chin? this would minimize the drag concerns; however, if your mask ended up blocking your mouth or even choking your neck this maneuver would be detrimental.

cheers,
sean
vancouver

[azapa]

There is a great little drawing and explanation in Umberto Pelizzari's book about why it can feel so good down at 20M, and this why freedivers/spearos stay too long there. "Feeling of well being" is the expression used. The trouble is one forgets the time required to get to the surface. I have the cressi "MARSELLAISE" belt, and on too long dives unbuckle, the belt stays on though, one hand stops the trailing end slipping through the buckle. I will unbuckle before even heading up. I guess thats what you meant by holding belt in your hand.

Safe dives.

[harbour seal]

hello all,

i received some wise council from island sands in response to this thread, which led me to posting.

i just wanted to clear up that i don't think anyone should immediately take sebastian's findings as gospel. i don't think any one diver's ideas, in isolation, should be taken as gospel for that matter.

personally, i think mask removal is a rather interesting idea but ultimately does nothing if it has no practical utility for most divers. hopefully the community will start thinking about/testing mask removal under safe and controlled conditions.

only after wider testing by different groups of experienced divers, can we evaluate if it is ultimately a worthwhile technique and under what conditions it should/should not be employed.

in the end it may not be worth the effort or even hazardous in certain situations (as many have mentioned) or it could in fact be a life-saving maneuver that ends up being taught in PFI/FIT/etc teaching as invaluable in the right situations.

cheers and thanks for all of your input,
sean

[Job.Romijn]

I have been thinking about unlocking the buckle of my weightbelt on ascent, but never got around to actually doing it.
Probably because i didn't feel that i'm pushing it yet.

However, the comment from Eric about the shallow dive getting hairy because of the lack of surface/recovery time made me think:
This could happen to me too!

Also the idea of making this safety measure an automatic thing sounds very plausible.
So i will start experimenting with this now, because it will be to late to start when i do get into trouble.
It will probably make me feel even safer going up!

Another thing i thought might help is putting the weightblocks on the back of my weightbelt (instead of my belly, or evenly distributed).
This should help me floating on my back, face up, especially if i'm unconscious at the surface.

If the weight is hanging on my belly, i tend to float face-down. That doesn't help the breathing process...

I realise the weight distribution doesn't matter anymore after dumping the belt, but i want to try constant weight without fins as well. I'll be needing both my arms to propel me back up to the surface then, so no free hand to hold the buckle!

Job

[sebastien murat]

Mr Harbour Seal asked if I could elaborate further on this mask-removal thing:

The sooner you remove it the better. Ideally you'd dive without it, but if not, then immediately upon ascending...not when your in the steep part of the ambient pressure gradient. Furthermore, you ideally want to tape into colder water as soon as possible, which is generally that found below the thermoclines. Cold aside the added stress will further lower your O2 consumption rate. This strategy is not for use when your diving within your aerobic dive limit, i.e., easy diving, since there should be no excuse for blacking-out then. Its use is strictly for pb diving or for emergencies if you're in the habit of diving with a mask.

PS: Island Sands.....The notion of realizing your full O2 conserving dive response in a relaxed mental state, as some teach and continue to teach, is simply *******s; animal diving physiologists have known this since at least the 1940s. There's ample amounts of literature out there so this is nothing new.

My two bits
S

[sebastien murat]

*******s = b o l l o c k s

S

[azapa]

Originally Posted by naiad

I am not too sure about the whole dive reflex thing. For me, cold water on my face, or being in cool water, reduces my apnea time and increases the risk of blackout. I am not sure why this is, but it has consistently proven to be the case for me.

Naiad,

Seeing as no one believes your cold=worse apnea scam , I will offer you a possible explanation from my very limited experience:

I guess you must be confusing cold water with the "scariness" of open water?? Murky, cold, deep, full of sharks and other imaginary beasties(!), the sound of outboard motors buzzing etc. My apnea is reduced by 50% when I can't see the bottom, diving into the murk. Just takes practice and a good buddy to overcome.

safe dives.