Dangers of Breath-Hold Diving

[Kings Gambit]

In another thread there has been brief discussion of reports of the tragic death of a fellow boater who, according to one report, dove on his anchor to free it, as it evidently had become fouled on something. The depth of the water was not mentioned. But regardless of the full set of circumstances leading to the above-mentioned tragedy it has occurred to me that while people don't much think about it, breath-hold diving can be a dangerous activity, especially in cold water. People trained in SCUBA diving are given some instruction, but since most recreational SCUBA divers are trained by instructors of sport shops looking to expand the sport (and sales), training in breath-hold diving is not a priority item. Even among some types of professional diver training, it's not emphasized.

The principal cause of drowning while breath-hold diving among "fit", even fairly athletic, individuals is from passing out under water-- i.e., hypoxic blackout. Essentially, at some point during the activity, there's not enough oxygen reaching the brain. I would expect this to be accelerated in someone doing "work" (as in trying to free or move an anchor) on a breath-hold dive. Hypoxic blackout can come on without warning, even at shallow depths, and may occur on the ascent from a relatively deep dive. In people, the impulse to take a breath is driven by the build-up of carbon dioxide in the blood, rather than by depletion of oxygen there. So, it's possible for the blood to become dangerously low in oxygen (hypoxic) before the impulse to breathe becomes critical if there is hyperventilation, which rids the blood of carbon dioxide, before a dive.

Can find more information at the link below, but FYI:

Hypoxic Blackout - Prevention
1. Do not hyperventilate before breath-holding
2. Do not dive deep
3. Avoid excessive exercise
4. Avoid competitive behaviour resulting in the above activities
5. Ensure buoyancy near the surface
6. Dive with a buddy or have a safety observer/rescuer
7. Educate breath-hold divers of this hazard

http://www.divingmedicine.info/Ch 04 SM10C.pdf

 

[centerline]

The principal cause of drowning while breath-hold diving among "fit", even fairly athletic, individuals is from passing out under water-- i.e., hypoxic blackout. Essentially, at some point during the activity, there's not enough oxygen reaching the brain. I would expect this to be accelerated in someone doing "work" (as in trying to free or move an anchor) on a breath-hold dive. Hypoxic blackout can come on without warning, even at shallow depths, and may occur on the ascent from a relatively deep dive. In people, the impulse to take a breath is driven by the build-up of carbon dioxide in the blood, rather than by depletion of oxygen there. So, it's possible for the blood to become dangerously low in oxygen (hypoxic) before the impulse to breathe becomes critical if there is hyperventilation, which rids the blood of carbon dioxide, before a dive.

Can find more information at the link below, but FYI:

Hypoxic Blackout - Prevention
1. Do not hyperventilate before breath-holding
2. Do not dive deep
3. Avoid excessive exercise
4. Avoid competitive behaviour resulting in the above activities
5. Ensure buoyancy near the surface
6. Dive with a buddy or have a safety observer/rescuer
7. Educate breath-hold divers of this hazard

http://www.divingmedicine.info/Ch 04 SM10C.pdf

I agree....
also found under the term "shallow water blackout"... due to the pressure at depth, usually in excess of 10-12ft, (risk increases with depth, time, activity) the air cavity in the lungs is compressed and the volume of air is condensed (which is not dangerous in itself), but the body is able to consume/use more of the oxygen out of the condensed air in the lungs... and so, when the diver surfaces and the compression lessens and the air expands to its original volume, there is not enough oxygen molecules left in it to sustain consciousness.... and before the body reaches the surface, drowning occurs....

 

[Ken Cross]

Thanks for this important post.

When I was a young guy I was diving on a stuck anchor behind my 16 foot runabout. I had a 75 foot rope attached to a light steel Danforth and the line was almost vertical. After hyperventilating I dove down and found the anchor stuck between rocks. I pulled it out and swam with it in one hand up toward the surface. Once It began getting light (I thought nearing the surface without looking up) I began expelling my breath because I needed air badly. I then looked up and saw I was more than a boat length below the surface. Clearly thinking wasn't a factor because I continued to swim to the surface with the anchor in hand. I handed off the anchor and took a gulp of air. Then my lights almost went out. Untrained and foolish but lucky I guess.
Ken

 

[Kings Gambit]

Yeah-- the entire stuck-anchor thing presents a conundrum to a boater. There has been much written on potential remedies but I don't recall reading one recommending a breath-hold dive to free it, especially if near twilight in cold water, even with a wet suit on. There's also the possibility of ear drum perforation which if occurring in cold water can be exceedingly disorienting if one does not pass out from that itself. There was a report a few years ago of some NFL players fishing in the GOM several miles (at least 30, I believe) off Clearwater, FL. Some weather threatened to come in so they wanted to pull anchor and head in but the anchor was stuck. I don't recall all that was reported that they tried to do, but in the end they attached the rode to a stern cleat and powered up the boat to pull it free. The boat flipped (turtled) and there they were. I think one survivor was eventually rescued.

My anchor is on 160 ft of 5/16" SS chain; I'd definitely be loath to leave it and a fair shot of chain behind stuck, for example, in only 30 ft of water . I suppose it's best to prepare yourself with those "sanctioned" remedies and resist that "last-ditch effort" to dive on it while breath-holding. On SCUBA, however, it would be a fairly straightforward, and comparatively safe, activity to attempt to free a stuck anchor. As I mentioned in another thread, I carry an 80 cu.ft. tank and a regulator on a 25' hose, mostly there for bottom cleaning and examining the prop if need be. With some finagling, I could probably get to 40-50' by lowering the tank to 25' and then descending from there. Of course, a longer hose would be a much better solution!!

 

[Rich Stidger]

A stuck anchor is a situation that can be remedied by a call to Tow Boat US or another of your favorite water distress companies. There is no need to put your life at risk to dive 15 or more feet.

However, this thread is interesting to me. Last summer I needed to clear a long length of line from my prop. I dove to the prop numerous times with my hook knife before I completely ripped it to shreds and removed it. I was only going a couple feet below water, but it was an exhausting task. I can't even imagine diving as far as the bottom of my keel, never-mind to an anchor further down.

Now I am wondering if my actions to dive on my prop was a really stupid thing to do. I was not near any services and I was concerned about damage to my running gear if I ran it.
Do I get a Darwin Award?

 

[Anonymous 121765]

Guys,

I sail, fish, dive & spearfish otta of Tampa Bay waters.

Losing this SOLDIER was a personal loss for me. We will probably NEVER really know what happened but,
I do know that I almost drowned in 10 feet of water pulling up a kedged anchor some 25 years ago.
I can go into detail but, never pull on an anchor standing two feet on the bottom unless you are sure it is NOT MUD! If it is hard packed sand or rock, that's fine but if it is a mud bottom, NO NEVER!

Pulling the anchor free, I sank in up to my knees but, rotating my knees in a circular motion I was able to break the suction & get to the surface. I was real lucky that time for I thought I would die. I only sucked air for a 30 second dive. I didn't get to the surface for about 1-1/2 minutes chocking & gasping air.
The hell with and anchor as that is easily replaced. your life can be a different story.

While all this was happening, I had visions running thru my mind of a drowning victim &....film @ 11:00.
I was lucky as being stupid, I did not know of the dangers. This was very SCARY.

He had hand-held air on his first two dives. In that area, there are stiff currents.
Was He standing in mud, we may never know? What we DO know is that it was his 3rd.
dive down to 30 feet killed him. Did he have air with him then,......who knows at this juncture?
Did I know him, probably not.

Something went HORRIBLY wrong........and he never resurfaced. The really SAD part is that,
he is no longer with his family. His loss hits close to the vest with me & fellow local divers.

Stay safe, think first & do NOT take STUPID chances, it's NOT your universe, you're in theirs.

CR

 

[shemandr]

Thanks for relating these experiences. I used to clean my keelboat bottom and keel diving with a snorkel and mask. I quit SCUBA because it scared me - I just wasn't comfortable. To clean the keel without SCUBA I would hyperventilate perceiving it would help me stay under longer. I always thought you couldn't get in too much trouble free diving in shallow water. I had never heard of Hypoxic blackout or Shallow Water Blackout in the context of free diving. And now I have.
My sympathies to the family and the wife who experienced the horror of waiting for her husband to surface - terrible.

 

[Kings Gambit]

A stuck anchor is a situation that can be remedied by a call to Tow Boat US or another of your favorite water distress companies. There is no need to put your life at risk to dive 15 or more feet.

However, this thread is interesting to me. Last summer I needed to clear a long length of line from my prop. I dove to the prop numerous times with my hook knife before I completely ripped it to shreds and removed it. I was only going a couple feet below water, but it was an exhausting task. I can't even imagine diving as far as the bottom of my keel, never-mind to an anchor further down.

Now I am wondering if my actions to dive on my prop was a really stupid thing to do. I was not near any services and I was concerned about damage to my running gear if I ran it.
Do I get a Darwin Award?

Rich-- We've both probably seen this done a number of times. During a companion boat cruise of a few years ago I watched w/ concern as one of my buddies past 60 yr old use breath-holding in an attempt to unwrap his stern anchor rode from the prop of his powerboat. (One more reason why I'm not a fan of stern anchors.) Several trips under, w/o even snorkeling gear, wearing only a swimsuit in water < 70 deg F, he finally got it off. Yes, exhausted he was. We could have gotten him free using SCUBA but he didn't wish to wait (or to "trouble us"). I carried a pony bottle (for SCUBA) on my old P-30 for underwater work on the boat. If you have SCUBA certification, it's nice to have one of those and a regulator aboard. They're only about $125-150; a regulator is more, of course.

My wife just handed me this story in the current issue of the The Log taken from another publication, the Easy Reader News. The body of a well-known local spearfisherman (Mr. Poznik) was recovered from the waters off Palos Verde a couple of weeks ago. Evidently, he was trying to bag a white seabass spearfishing (i.e., breath-hold diving). Out there alone in a borrowed Boston whaler. Autopsy not in but the leading suspect for cause of death at this point is:

Hugoboom said Poznik could have been hit by a boat or a shark. “Boats speed through there. I’ve almost been hit a number of times,” Hugoboom said. A shark attack is the least likely cause, he said. The most likely, he speculated, is shallow water blackout, a result of an imbalance between oxygen and carbon dioxide in a diver’s blood stream. “Taras was a very good, experienced diver. He was big and strong. But a lot of experienced divers have shallow water blackout. It’s a common cause of fatalities,” Hugoboom said.

http://www.easyreadernews.com/12485...ras-poznik-dies-pursuit-giant-white-sea-bass/

 

[waterpirate]

If you have never seen shallow water blackout or hypoxia on a rebreather. You tube will cure you of any foolish thoughts you may have about free diving for a anchor. We frequently free dove solo until one day during a competition my friend came up from depth, gave me the o.k. signal and God turned him off like a switch. Suddenly and without warning. I and others rescued/revived him, happy ending. We never dove solo again after that, ever.
Eric

 

[justsomeguy]

Do I get a Darwin Award?

Did'ja die? No?
No Darwin for you!
I suppose you could rig up a quick release tether, but you did what you felt you had to do.

 

[Kermit]

Did'ja die? No?
No Darwin for you!
I suppose you could rig up a quick release tether, but you did what you felt you had to do.

+1
All Darwin Awards are given posthumously. All winners actually help the gene pool by not passing theirs to the next generation.

 

[Sailm8]

When my anchor needs help getting up, I call for help.

 

[Kings Gambit]

Did'ja die? No?
No Darwin for you!

Darwinian Fitness is defined as the probability that a certain genotype will contribute to the next generation viable offspring that survive to reproductive age, and it (the probability) is relative to other members (i.e., genotypes) of a population. If you die after having healthy kids who make it into adulthood, no "Darwin award". However, it's possible that the least dopes in a population of really stupid dopes might still pass on dope genes.

 

[Mark Maulden]

Anybody have any experience with this?
http://www.anchorrescue.com/

 

[Dan_Y]

Another way to explain SWBO is that as you descend from 1 atmosphere of pressure (ATM) the partial pressure of oxygen (ppO2) ppO2 and nitrogen (ppN2) are about 0.2 and 0.8 ATM respectively. They have to total to 1 on the surface. If you quickly descended to 33 feet of depth in saltwater (FSW) you are now at 2 ATM of pressure - one for the surface pressure and one for the weight of the water at 33 feet. The ppO2 is now 0.4 ATM and ppN2 1.6 ATM (they have to add to 2 ATM). I seem to recall that you need about 0.1 ATM ppO2 or a tad +/- to stay awake. Imagine now your body is metabolizing the O2, so your ppO2 begins to drop. If you were to stay at 33 ft until your ppO2 dropped from 0.4 to to say 0.2 ATM, then ascend from 33 ft, your ppO2 would be 0.1 as you neared the surface and you could turn off. The rebreather example is a good one. If you don't keep sufficient pp02 in the breathing loop, even if your CO2 scrubber is working fine, you can turn off, even in the bottom of a shallow pool. In both cases you are hypoxic, as pointed out above. Divers with gas powered air pumps for breathing or filling tanks can get CO in the tank. On the surface t is bad enough and could cause a bad headache before going out. The ppCO increase at depth accelerates the effect.

 

[centerline]

Another way to explain SWBO is that as you descend from 1ATM the ppO2 and ppN2 are about 0.2 and 0.8 ATM respectively. If you quickly descended to 33 FSW (2ATM), the ppO2 is now 0.4 ATM and ppN2 1.6 ATM. I seem to recall that you need about 0.1 ATM ppO2 or a tad +/- to stay awake. Imagine now you are metabolizing the O2. Your ppO2 begins to drop while you are at depth. If you were to stay at depth until your ppO2 dropped to say 0.2 ATM, then ascend from 33 FSW, your ppO2 would be 0.1 as you neared the surface and you could turn off. The rebreather example is a good one. If you don't keep sufficient pp02 in the breathing loop, even if your CO2 scrubber is working fine, you can turn off, even in the bottom of a shallow pool. In both cases you are hypoxic, as pointed out above. Divers with gas powered air pumps for breathing or filling tanks can get CO in the tank. On the surface t is bad enough and could cause a bad headache before going out. The ppCO increase at depth accelerates the effect.

as a professional diver, I know what all this means, but lets try to help the ones that dont know..... without the training necessary to know better, all these ppo2's and atm's and ppn2's are only confusing to the people that you are trying to inform.... those of us that know, already know.
its needs to be spelled out to make it a bit more interesting and helpful read...

and I only say this because it really pisses me off when I ask someone a math question and they come back with a formula that only a math major can decipher.... and they expect me to know what they are saying, when all I wanted was the ANSWER.
if I could read the formula, its highly probable that I wouldnt have to ask the question to begin with.
which is kinda the same with your post...

 

[centerline]

He had hand-held air on his first two dives.
Stay safe, think first & do NOT take STUPID chances, it's NOT your universe, you're in theirs.

CR

"He had hand-held air on his first two dives."

without the proper training, and in most cases, with it, hand held air is more dangerous than free diving.

to take a new breath of "canned" air at depth, and then return to the surface while holding it in, will burst the lungs... can we all say arterial gas embolism?.... training, training, training.... "Stay safe, think first & do NOT take STUPID chances, it's NOT your universe, you're in theirs."

 

[Kings Gambit]

I admit I did not know until now about "canned air", which is sometimes sold under the moniker of "Spare Air." It's an emergency air-delivery device for SCUBA divers who run out of air while submerged. Strange device. When I got my first diving certification in 1971, we had K-valves on the tanks. When it became hard to draw, you went up; end of dive. Then came J-valves with hand-control levers that did not force ascent but let you know that you were "on reserve" after pulling the lever, then octopus regulators with pressure gauges so you could actually see how much air was left for you (and your buddy if he needed your extra regulator), then pony tanks when your main tank actually did run out and you were still down, and now this thing: "Spare Air." A potentially dangerous piece of "safety equipment" IMHO even if used as intended. In the more advanced diving certifications one must demonstrate free ascent from 100 ft (no-decompression dive). When out of air you (and your buddy) are supposed to come up, not dork around down there with a hand-held "Spare Air" canister in your face.
So, I have to agree with centerline.

http://www.spareair.com/product/models.html

Here's the company promoting use of the device as an aid to breath-hold diving (under tips and tricks), among other things. I wonder if a cert is required to possess and use one of these things?

"Free an anchor. When we're ready to enter or leave a dive site, it takes no time at all to grab a mask and Spare Air, jump in the water and free up the anchor without destroying the coral or other sea life."

http://www.spareair.com/product/operation.html

 

[DaveJ]

Back to the original post, I have done this twice. Once in BVI and once in Lake Ontario. I didn't realize the danger that I have put myself and my wife in. I do these things because I always do.....
Thanks for posting this, it should be a reminder for us.......

 

[chuckwayne]

Yes! works great - met the inventor (from Maine) at the Newport boat show when it was introduced, bought one on the spot. tested it on my delta set hard in Maine mud and it worked well. What was really impressive was that a year or so later they introduced an improved recovery collar and sent it, unasked and free, to every owner.