Relative risk in diving

[Blackcrusader]

Although recreational diving can be very safe, DAN wouldn't have to compile accident statistics if diving were as safe as a walk in the woods

A walk in the woods where I live can be more dangerous than the diving I do. My wife calls me Dances With Cobra's. Where I live vipers, cobras, pythons, killer hornets, bears, wild boar, monkeys and other nasty critters live. I live in their domain. Recently a few of our cats died after being bitten by snakes. The only thing missing up my way are mountain lions as we don't have them in Taiwan.

 

[Blackcrusader]

Hi! I'm currently working on a research project surrounding public perception of the risk involved in diving and other sports (for a class), and have been trying to gather more responses from people who have experience diving, as that demographic is much smaller at my school than with most other sports. If you have a few minutes and could take this really quick survey that would help so much! It should take at most 2-3 minutes, and since the questions are very broad you don't have to worry about your responses too much, it's definitely relative to the individual- here's the link:

Perceived Risk Levels in Various Physical Activities:

I'm relatively new to diving and to this forum, so if there's a better area you think I should reach out to I'd appreciate any suggestions, thank you all!!

I think you should add skiing to your list. Hospitals do a roaring trade with injuries during the ski seasons.

 

[rx7diver]

We used a similar system with twins, one tank was breathed down and when empty the other was turned on and decanted into the empty one. This was in turn turned off and the other tank used. The second decanting would leave over 50 bar in both tanks.

IIRC, @Akimbo has described a similar approach for the inverted baby doubles he used to dive.

rx7diver

 

[John C. Ratliff]

This is not true. While I didn't use the three mount bottle system as they were too expensive for me, I did dive a j-valve. On more than one occasion, when I went to use the reserve, I found that the switch had already been done. Either I forgot to set it before the dive, or it got bumped during the dive. Fools are an ingenious lot and we'll find ways to circumvent any safety measures. I finally broke down and bought an SPG around the turn of the century. To date, I've yet to run out of air underwater since. Ergo, I prefer a gauge, either on a hose or as part of an integrated PDC.

What you say is true of the J-valve, under some conditions (I have mine configured so that this inadvertent tripping cannot happen). For twin tanks with a J-valve, it involves rotating the cylinders so that the reserve is on the right side, instead of the left side (see the photo below). For single tanks, some manufacturers (Scubapro, Dacor) allowed reversing the lever.

But it is not true of the Cousteau system, as he used it and as it is described in the Cousteau & Gagnan patent:

For the operation of the unit the three cylinders A, B and C are first filled with compressed air, the cocks K and L being closed. Before sinking, the diver, who wears about him all the apparatus, opens cock K, cock L remaining shut. Under the inspirations of the diver, the valve member In of the low pressure regulator E opens by an amount just necessary for the breathing. When the diver feels that his normal supply of air is on the point of being exhausted, h opens the cock L and slowly rises to the surfac l.

 

[Akimbo]

IIRC, @Akimbo has described a similar approach for the inverted baby doubles he used to dive.

Yes, the progressive equalization technique was taught to me by an ex Royal Navy diver. As explained to me, it was developed for working in zero visibility and/or diving without an SPG.

 

[Blackcrusader]

But they might lack the strength or stamina...

Here is one of me chasing a whale shark. Gorgeous creatures to get shots of. Depth was around 30m. I was catching up to it and really only stopped as the other dive buddy I pass and I were really putting in some distance from the rest of our group who gave up trying to keep up with us. Audio gives you a good record of my breathing. One of the divers got leg cramps. Back on the boat some of the young guns were asking me how come you didn't have a heart attack with all that effort lol. 300 pound 60 year old fat dudes should not be able to do this. I really should have kept going a for a few minutes more.

 

[rx7diver]

... Some dive solo even at 50 years old plus (what about the risk of heart attack) and feel perfectly safe. ...

@Dody,

I think you'll find quite a few of us solo-diving seniors here on SB. See my avatar? That grey is real!

rx7diver

 

[John C. Ratliff]

Here's the reference to the use of gauges in the Cousteau-Gagnan patent on the Aqualung:

Referring to Figs. 1, 2 and 3, A and B are two cylinders containing compressed air but which might as well be filled with any other compressed breathable gas. On the cylinder A is mounted a cock J through which the compressed air is ad mitted to the two cylinders for the purpose of filling them. The air inhaied by the diver is withdrawn from the cylinders through a common pipe N. A third cylinder C serves as a reserve; the gas contained in it being available for the diver when he feels that the supply of gas contained in the two cylinders A and B is close to being eihausted. The capacity of this third cylinder is sufliciently large to, supply sufllcient air to the diver to enable him to rise to the surface sufficiently slowly. The diver can thus dispense with any instruments for measuring the pressure in the two cylinders A and B. The air is withdrawn from the reserve cylinder C through a pipe 0. Pipes N and 0 are provided with cocks 'K and L, respectively, which are operated by the diver. While two cylinders A and B have been shown for the normal supply of air to the diver, only one could be utilized instead.

US2485039A - Diving unit - Google Patents

patents.google.com

Emphasis mine.

SeaRat

PS, I'm 76 years old, and plan to be diving this spring and summer in the Clackamas River, here in Oregon.

 

[clownfishsydney]

The problem is some people do not seem to have any situational awareness of danger and risks, whether it is driving, diving, boating or whatever. These are the people who are more likely to die from an activity when they push it.

Personally I have known a few divers who did not seem to appreciate the dangers of how they were diving and the potential risk to them and others. Of those, most died diving. A few we managed to talk them out of the sort of diving they were doing or in at least one case, convince him to stop totally.

These sorts of people also do not seem to learn from their mistakes (or those of others) or learn from other incidents caused by taking an abnormally high risk. For example, diving in very rough seas or strong current and getting away with it after a very close call with death or bad injury, and then doing it again and again.

 

[Celt]

If one is unable to watch its gauge in the first place, what make you think that he/ she will pay attention to the second? Like, I still have 100 bars, I can go on.

You’ll pay attention when you’re sucking the rust out, you may not be able to see the gauge or not have one. I’ll put up a photo of my Poseidon,s after, as the valves were easy to get to.