Provocative talk yesterday at NSS-CDS: Toss out the rule of thirds?

[Manatee Diver]

Or can't find dive buddy because they are a distracted, unsafe diver and no one wants to dive with them.

When diving with a buddy I have to resist the urge to check out every little thing I see. Probably a good 10 minutes of each dive is "I wonder what that is" going back and looking.

 

[CG43]

The best sport that will prepare you for cave diving is cave diving.

Do you agree with this addition?
"The best sport that will prepare a diver for cave diving is cave diving .

Muscle memory is required to perform skills correctly. But just as important is that the involuntary adaptations to the underwater situation are carried out correctly.
The normal situation, i.e., breathing while scuba diving, is practiced sufficiently, not the situation where breathing is not possible. Therefore, the diver must not develop physiological adaptations for this.

If every dive is "problem-free" you're blind and not reflecting *critically* on each and every dive with the aim of continuous improvement in skills and attitude.

Your are right , but let us talk about the cases that rises up the RMV hight and how to avoid this .

Some good advice has already been given here, and I'd like to add one that seems very logical to me:
If you dive without scuba often enough, a whole series of physiological adaptations occur, and not breathing is no longer automatically viewed as quickly life-threatening .
With that in mind, it is unlikely that the RMV will increase significantly.

 

[steinbil]

Some good advice has already been given here, and I'd like to add one that seems very logical to me:
If you dive without scuba often enough, a whole series of physiological adaptations occur, and not breathing is no longer automatically viewed as quickly life-threatening .
With that in mind, it is unlikely that the RMV will increase significantly.

While I do agree that free diving will be beneficial to scuba diving in terms of water comfort, moving effortlessly under water and breath control – possibly also in terms of increasing the tolerance for CO2 – I don't know if it will help the mental stress that occurs when you think you might die.

I would hope that most cave divers are comfortable holding their breath, changing regs, breathing a hose dry, donating gas, so it shouldn't be the mechanics of breath holding that is causing the massively increased RMV. Rather the uncertainty of survival, which is hard to prepare for. But I think comfort in the cave environment and repeatedly trusting the procedures to get you home safe, mixed with some mishaps you have survived, might make it easier to focus on the task of getting home rather than stressing over the possibility of your demise.

 

[rjack321]

Some good advice has already been given here, and I'd like to add one that seems very logical to me:
If you dive without scuba often enough, a whole series of physiological adaptations occur, and not breathing is no longer automatically viewed as quickly life-threatening .
With that in mind, it is unlikely that the RMV will increase significantly.

You don't seem to have any cave training or experience. The very real risk of drowning tends to make people really anxious over the course of a long exit with less and less gas available by the minute.

 

[lermontov]

First and foremost, "Know thyself". Acknowledge your weaknesses. What situations on "normal" dives makes your heart beat a bit faster. Then, if possible, train to overcome those weaknesses or situations that trouble the diver.

excellent comment!
Each time you get into a situation that creates a stress or exposes a weakness is an importunity to grow, but not everyone wants to 'overcome' What was stressful on your first few dives is not stressful anymore because youve stretched your, lets say - stress horizon
Going forward, once weve been in a few situations that has exposed you both mentally and experientially we tend to back off somewhat.

However the stress horizon (or space ) is slightly bigger than it was before the event - you dont really go back to where you where before, thats how you stretch and gain experience and consequently get more comfortable.

Ive been in a few situations that i genuinely feared for my life - Ive had to give myself a severe talking to at the time eg "peter, if you dont get your **** together your going to die here " sort of thing.

The problem is that sometimes we fail to recognise how far out weve pushed the boat. We can see it in others, but sometimes its hard to see it in ourselves, I value my dive companions opinions

 

[ofg-1]

I went to the NACD conference in 1975, and people were quibbling about rule of thirds and 1/2 plus 200 then. Its like the flat earth theory, it just hangs around.

My conclusions over the years are this. No one will take away your birthday if you surface with 1/2 full tanks. If you want to go further, take a stage. More, take 2. Want a low rmv, get a scooter. Going to scooter further than you can swim out, get a tow scooter. Even more? Do a setup dive and drop safeties. If you can't deal with the gear, don't do the dive.

 

[CG43]

While I do agree that free diving will be beneficial to scuba diving in terms of water comfort, moving effortlessly under water and breath control – possibly also in terms of increasing the tolerance for CO2 – I don't know if it will help the mental stress that occurs when you think you might die.

In my experience, when I couldn't find my way out under ice, it helps in two ways.
1). As a freediver you practise allowing contrary breathing .
These refex-like breathing movements help to attune the body to oxygen-saving measures . As a result, I no longer had to deal with the feeling of shortness of breath because now there was the next problem.

2). The emotions of dying here and now are not easy to bear. However, the diving reflex also helps here because it concentrates the diver on the life-sustaining functions. At least this is my experience, but this concentration also has a price .

Example 1). When I was getting nervous during an exam, I imagined myself underwater and holding my breath. This did calm me down, but I failed the exam.
Example 2). Before my first parachute jump, to calm myself down, I imagined holding my breath underwater. It worked very well. However, I had decided to check beforehand whether the automatic line was securely attached to the plane. I didn't check.
Overall, the advantages over a hectic or even panicked diver will outweigh the disadvantages.

 

[CG43]

You don't seem to have any cave training or experience. The very real risk of drowning tends to make people really anxious over the course of a long exit with less and less gas available by the minute.

You're right on all points.

However, I often dive in murky water under boats/ships/pontoons up to 30 meters long and rarely in caverns and ice. My longest way out was estimated at 60 m and there was still a very faint glow of light from the entrance of the cave .
There are also similarities between deep freediving and cave diving. You have to make it back up the way you descended. So you have to stop and turn around in time, and assess your oxygen levels.

 

[bipolarbear]

Stratis Kas addressed this at length in the talk - this is NOT a physiological problem of being "in shape," it's a psychological stress response. I'm a research psychologist, and he is right. We use physiological measures such as heart rate and respiratory response as dependent measures when studying stress and anxiety, because they skyrocket under stress - even if the person reports feeling calm. That is, you can feel calm and in control, and still find your respiratory rate increasing by upwards of (at the highest end) 700%.

Kas and colleagues have been modeling this and that was a large part of his talk, that you need to account for not only a stressed recipient, but also a stressed donor, both of whom are likely to be using far more than twice the gas they used to enter the cave on exit.

There's an excellent old post by Andrew Ainslie about the massive amount of gas he blew through during an incident at the back of Ginnie: How Much Gas is Enough? Running on Empty

Ainslie's article gave me chills.