Rule of Thirds & Shallow Rec diving

[Foxfish]

Foxfish you are impossible. That 85B number I came up with was from your ridiculously liberal numbers giving no consideration to your buddy. MY numbers are far more in line with what everyone else is trying to say. This is the first time I have seen someone just throw away knowledge for an inferior system. I hope we don't read about you in one of Don's post one day. I'm sorry you'd rather chance drowning or getting bent than properly planning and executing a basic gas plan. It's sad honestly.

Maybe you forgot about this calculation you did a little while back for an emergency ascent involving two divers breathing at 30 L/min. You came up with about 88 b as the required pressure.

Let me post this YET AGAIN foxfish
1 minute at 30M
3 minutes to get to 5M
3 minutes at 5M
30 seconds to go to surface...

30Lx2x4ata= 240L
30Lx6x2.8ata= 504L
30Lx6x1.5ata= 270L
30Lx1x1.25ata= 38L

If you were talking about a 12L 232B cylinder then you need 88B (round up to 90 so you can actually read the gauge) again 10B will make a difference.
​

I used similar numbers and got about 81 b.

Let me say it again. Your argument is with the major recreational diving agencies who teach the 50 b rule. I'm simply taking typical results used for a rock bottom calculation and noting that I get a similar ascent pressure to what I'd need if using the 50 b rule.

Am I being impossible or very patient here?

 

[Storker]

*Shrug* His last few posts have been too ridiculously obstinate and sidestep direct answers. Searching for a reason why, it hit me.
His profile says he's an engineer.
Bada-bing.

Not quite bada-bing IMO.

A man in a hot air balloon realized he was lost. He reduced altitude and spotted a woman below. He descended a bit more and shouted, "Excuse me, can you help me? I promised a friend I would meet him an hour ago, but I don't know where I am."

The woman below replied, "You're in a hot air balloon hovering approximately 30 feet above the ground. You're between 40 and 41 degrees north latitude and between 59 and 60 degrees west longitude."

"You must be an engineer," said the balloonist. "I am," replied the woman, "How did you know?"

"Well," answered the balloonist, "everything you told me is technically correct, but I've no idea what to make of your information, and the fact is I'm still lost. Frankly, you've not been much help at all. If anything, you've delayed my trip."

The woman below responded, "You must be in Management." "I am," replied the balloonist, "but how did you know?"

"Well," said the woman, "you don't know where you are or where you're going. You have risen to where you are due to a large quantity of hot air. You made a promise which you've no idea how to keep, and you expect people beneath you to solve your problems. The fact is you are in exactly the same position you were in before we met, but now, somehow, it's my fault."

I suggest that he may be a manager.

 

[rivers]

Now if we extrapolate over the past ten years using 2013 data then there would be an estimated 70 incidents involving drysuits. You could check that as well. Then you could check the records or ask anyone to provide records of the number of incidents involving divers who began their ascent with adequate air in their tank to surface with 50 b in the tank under normal conditions and had an OOA incident that lead to injury or fatality. So far to the best of my knowledge the tally stands at ZERO. If you know differently do tell.

I note that you previously calculated that the amount needed for an emergency ascent was 80 b in similar circumstances to the ones I described in the above recent posts.

Please retract the comment that I lied. It has no place on this forum.

There are over 35,000 BSAC members in the UK. Say 30,000 are active UK divers. There are probably another 20,000 or so divers in the UK that are not affiliated with BSAC and are also active UK divers (by active UK divers, I mean divers who actively dive in the UK). So that is give or take 50,000 divers. In my experience about 95% of UK divers use a drysuit, so 95% of 50,000= 47,500 divers in the UK are diving in drysuits. A UK diver, on average, probably does around 50 dives in the UK a year (some do more, some do less. I myself currently have 133 dives this year and will most likely end up with a few more than that). So 50,000x50=250,000 dives of which 237,500 are done in a drysuit. So there were 7 drysuit incidents out of 237,500 dives undertaken in a drysuit. Those are some damn good odds of not having an incident caused by a drysuit.

 

[Storker]

Minor nitpick:

I'd rather phrase the conclusion as: "Those are some damn good odds of not having an incident caused by a drysuit."
Otherwise, I think your post is awesome.

 

[rivers]

Minor nitpick:

I'd rather phrase the conclusion as: "Those are some damn good odds of not having an incident caused by a drysuit."
Otherwise, I think your post is awesome.

fixed it for you

 

[Foxfish]

fixed it for you

And how many did you find that resulted from running out of air during an emergency ascent of a diver and his buddy while observing the 50 b rule?

 

[rivers]

And how many did you find that resulted from running out of air during an emergency ascent of a diver and his buddy while observing the 50 b rule?

Wouldn't know. Every diver I know (and I know a lot), from new to veteran divers, regardless of the agency he/she trained with, uses minimum gas as a rule. Why, because if something does happen (blown o-ring, reg free flow, hose failure, etc), they want to make sure they have enough gas to get 2 divers to the surface safely, completing all stops (whether a safety stop or a decompression stop).

 

[shoredivr]

Let's compromise: a troll in management.

Anybody wading through this thread has been given several methods to do safe gas planning that includes buddy's gas and take into account ascent rate and tank size, which is the takeaway from these pages.

 

[rongoodman]

I'm starting to feel real pride as being the first to mention Minimum Gas back in post #7.

 

[Storker]

Let's compromise: a troll in management.

I'm fine with that :cool2: