Shallow Water Blackout

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Shallow Water Blackout

Postby SeaBear » July 22nd, 2020, 2:01 pm

Hi Everyone,

Can anyone point me in the right direction for scientific articles discussing the mechanisms behind shallow water blackout?

I feel like there are levels to the dangers behind shallow water blackout. I'm still fairly a beginner, and in SoCal 90% of my dives are 0-30 ft and under a minute, with plenty of recovery time. From the preliminary research I've done, the majority of blackouts are happening to those extremely experienced divers, reaching depths and bottom times far beyond my capabilities.

If I decide to go out on my own, and stay in the shallow reef at 15 - 20 ft deep, is that still as big of a risk as a 70+ ft dive? Surely diving for halibut in 10ft of water alone is safe? Again, if anyone can offer a scientific, physiological perspective that would be greatly appreciate.

I am not knocking the IMPORTANCE and SAFETY of never diving alone and ALWAYS diving with buddy. I stick to that rule 95% of the time. I am merely seeking to understand the varying levels of risk, on a physiological level, as you dive deeper and longer. Thanks in advance. :D

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Re: Shallow Water Blackout

Postby chris oak » July 22nd, 2020, 7:35 pm

You can blackout in a pool, it is a pretty common with younger adults. Typically it happens to us in deeper waters although it's more of a time thing that seems to be critical. I'm no expert but I've almost blacked out at least once when cutting a fish out in 50 feet when I was beginning. Now I always rest up double what my underwater time is and also give it an extra minute or two if it's fish down really deep where I can feel the heart rate increase. You gotta remember, there's a lot of variables that will add to your risk and a lot of that is how tired you were on that last dive.

check google scholar and type in "shallow water blackout" in the search field, you'll have weeks of reading.
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Re: Shallow Water Blackout

Postby Behslayer » July 23rd, 2020, 1:19 pm

Check out this site which Ted Harty has put up. Free seminar on Freediving Safety.
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Re: Shallow Water Blackout

Postby Matthew Rice » July 23rd, 2020, 7:52 pm

Ted Harty is an interesting guy. He's clearly very knowledgeable and well spoken. Bill and I were jumping on to some of his live streams a while back to try and learn more. Bill always raises up the troublesome reality of extremely limited visibility diving and how one up one down isn't terribly practical for typical California conditions. The conversation always comes back to "use a float line" and generally doesn't go anywhere productive from there. I took that online course a while ago after having completed a beginning and an intermediate class, and there is certainly value in it, as there is with all professional free diving instruction. I think application of that value and transition into typical hunting conditions is where the difference between theory and typical practice is. I love to line dive when I can, but it is hard to apply the same safety concepts of meeting at depth etc. to deep hunting with limited vis. For people I know to dive with me under situations like I see Jon posting of Hawaiian uku diving, doing aspetto dives to over 100ft in CA water with a reel and potentially current is going to present very different challenges without gin clear water. Don't get me wrong, though. I want to be a student of the sport and in order to do so, I know I need to live to see the next dive. Ultimately, I think the best risk mitigation strategies are probably some combination of proper supervision and an FRV type piece of equipment. That said, people don't want to do anything that will take away from the chances of bringing meat home in an already extremely challenging means of hunting. I know I never want to burden family with the "what if", should something happen. I also don't ever want to burden a partner with the same thing Bill went through of taking a friend home in his baggage. There is a balance between risk and mission accomplishment that should certainly be more heavily scaled towards mitigating risk. Still trying to figure out exactly what that balance looks like.
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Re: Shallow Water Blackout

Postby NaClAddict » July 24th, 2020, 5:34 am

Honestly, the guys pushing through diaphragm spasms are pushing it IMHO. It’s like boating. Go out on 1/3 tank. Leaves 1/3 tank to get home and 1/3 to handle any changes.

I avoided a watch for years. I thought it would push me to dive deeper and longer. Instead it’s taught me I wasn’t doing long enough surface intervals. I know awesome WSB hunters who never spend more than a minute under water.
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Re: Shallow Water Blackout

Postby Behslayer » July 24th, 2020, 10:13 am

Hobbling out this morning (Worst Urchin Spine of my life required Foot Surgery.. haven't been able to walk for over a week) to a Spearfishing Safety Seminar geared towards Kids and New Divers put on by an ultra experienced Hawaiian Waterman Bruce Ayau down at one of the local Spearfishing spots. Bruce put out the word of this free seminar on Social Media. Most Three Pronging kids I know will be attending. We've had a miserable summer of consistent Spearfishing and Freediving deaths of young people over here. Bruce is stepping up to the plate to raise awareness and make Safety the First part of the consideration of going out to get some fish.

The question becomes. Do you change your diving from first priority is Bringing home Fish to first priority is Diving Safe. The two often are exclusive as with the example above of Cali Green Water Deep Drops..
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Re: Shallow Water Blackout

Postby dustyyoungblood » August 28th, 2020, 8:04 pm

Considering many many highly trained freedivers and friends of many here have died in SWB Makes this is a Difficult subject.

I just got back into doing some drops after a 4 year hiatus. Let me tell you it feels like starting back at zero. There is just no way I’ll be even thinking about hitting 50’ anytime soon. My body has to learn all over again, what seemed easy and normal a few years back, is now hard.

I’ve been in the pool teaching my 5 year old how to swim the last 2 months. She decided a few weeks ago she could swim, but she can’t. She treads water completely out of breath and dives to 4’, does a mermaid roll underwater, surfaces and barely gets her lips above water catching 1/2 a breath then dives again. She will do that for a 1/2 and hour and i know she’s out of oxygen reserves but she won’t stop because it’s so fun. I can’t leave her alone she’ll black out or sink guaranteed.

Chasing fish is like this. A few more seconds and I’ll have a shot, just a little deeper, I’m the best diver here so whatever it takes I’m getting a fish, i paid a lot for this trip so I’m going to keep diving all day. I really think this is what happens to people. They just get caught up in the process, and ignore simple things like breathing more between dives. Stopping at any sign of a problem, like getting dizzy.

I can’t tell you how many times i just ended my diving day early, simply because i sensed that my body was feeling off, or tired, or got dizzy coming up. My non scientific answer is to always listen to your body. What would the free diving schools say about not pushing yourself past any uncomfortably?
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Re: Shallow Water Blackout

Postby Aussie » September 9th, 2020, 6:23 pm

I've probably blacked out half a dozen times (all during training or comps) and have had just as many samba's. I really recommend taking a freediving course. You'll learn more in a weekend about the mechanics of how your body functions than a lifetime of diving. Plus you'll be able to apply what you've learned to helping others.

To answer your question, in short, assuming you never dive beyond your comfort zone, you never hyperventilate, you take at least double the time on the surface as you do on a dive, you stay hydrated and don't dive when you're tired, you'll be fine.

But then, you could always get wrapped up in kelp after shooting a hot fish and have to deal with that. That was a fun dive... lol

Stay safe.
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