Rule of Thirds & Shallow Rec diving

[DaleC]

I have suspected that you were trolling for a while but thought the thread was producing a good discussion regardless. But it's becoming repetitive now.

I'm going to end this with 50b. No plan just: lkjgeirughieaorherhgoen;gnheqgfuihero;ghewrghwero;uigheriog50b.

 

[Foxfish]

If you cant recognize the inherent stupidity (or excessive over simplification) in making up a rule that says "be on the surface with XX psi", then nobody can explain it to you. Clearly, it makes more sense to tell a diver to leave the bottom with XX psi (or cu-ft, really) in order to reach the surface safely.

You can argue over how exactly one should arrive at the "rock bottom" reserve volume, but it makes a hell of a lot more sense (and it is vastly more practical) to know WHEN one needs to leave for a destination, rather than to simply say: "you need to arrive at XX hundred hours".


Sorta like: the plane leaves at 8.. great! But what time do we need to leave for the airport?

The problem with setting a pressure at which you'll start your ascent for all depths is that according to some on this thread, you'd be heading for the surface from 10 m with 110 b in the tank. The 'surface with 50 b' allows a diver to judge the air they need for a range of depths and make it less conservative. For a 12 L tank you may begin the ascent with

10 m requires 50+10 = 60 b
20 m requires 50+20 = 70 b
30 m requires 50+30 = 80 b

Try it out and see how it goes. You may need to tweek the number to suit the suit tank size or rate of air consumption.

I've never felt the need to prescribe these numbers up until now.

---------- Post added December 5th, 2013 at 09:15 PM ----------

Min gas is for WITHIN RECREATIONAL LIMITS! This is why Min Gas or Rock Bottom is so useful for rec divers, it's DESIGNED for rec divers specifically. It has to be extrapolated out drastically to fulfill tech diving needs.

Apparently not if you talk with the major recreational diving agencies.

 

[PfcAJ]

 

[dumpsterDiver]

The problem with setting a pressure at which you'll start your ascent for all depths is that according to some on this thread, you'd be heading for the surface from 10 m with 110 b in the tank. The 'surface with 50 b' allows a diver to judge the air they need for a range of depths and make it less conservative. For a 12 L tank you may begin the ascent with

10 m requires 50+10 = 60 b
20 m requires 50+20 = 70 b
30 m requires 50+30 = 80 b

Try it out and see how it goes. You may need to tweek the number to suit the suit tank size or rate of air consumption.

I've never felt the need to prescribe these numbers up until now.

---------- Post added December 5th, 2013 at 09:15 PM ----------



Apparently not if you talk with the major recreational diving agencies.

I just leave the bottom when it gets hard to breath... Very simple rule.. try it a few times.. PLEASE!

 

[Foxfish]

As some have said, the thread is starting to get repetitious. I've found it interesting and informative so thanks for your comments. This is evidently a controversial topic and that won't change. A forum like this gives divers an opportunity to share their ideas and see what others think even if they don't agree. It has served to highlight how much geographical differences affect the way we dive.

The low points are when people start attacking others personally or making derogatory, unfounded and sweeping comments about how they dive even though they follow the training of major agencies. Like the above childish comments, it is usually a sure sign the person making the attacks has run out of ideas or is unwilling to face the possibility that they may be wrong. This is supposed to be a flame free zone. We can do better than that.

 

[MXGratefulDiver]

So did the person who died begin the ascent with adequate pressure to hit the surface with 50 b. If not what does that prove? If so I'd be interested in a link to the article please.

No, she did not. She entered the water with what she thought was adequate air for the dive. She chose poorly and it cost her life. Cheryl was at least as trained and experienced as you are, and quite likely as confident that she knew what she was doing.

Here's the article.

http://www.seattlepi.com/local/article/Woman-who-died-scuba-diving-identified-1209387.php

Don't expect it to tell you much ... journalists aren't usually divers and almost always get it wrong. Her buddy at the time is in my dive club ... and so I got a bit more perspective on what occurred than you'll get from reading an article ... but you've already demonstrated that you don't believe anything I say, so I won't belabor the issue. Suffice it to say this ... there are many circumstances that can prevent you from beginning your ascent with adequate pressure ... human error being the most common one. Not everything goes according to the book ... and basic training frequently isn't adequate to keep you out of trouble. I only hope you don't ever have to find that out the hard way ... or if you do, I hope you survive the experience.

Come back to this thread after another few hundred dives ... you might be surprised at how your perspective will have changed about a great many things.

... Bob (Grateful Diver)

 

[PfcAJ]

Come back to this thread after another few hundred dives ... you might be surprised at how your perspective will have changed about a great many things.

... Bob (Grateful Diver)

I'm having too much fun with images tonight

 

[gcarter]

The most glaring issue I see with Foxfish's position is that it consistently ignores air for his buddy. If you want to dive on a best case scenario for yourself, feel free, but please do not buddy with me or anyone that I care about. You will not be able to provide help in an emergency.

 

[Storker]

Seems like it. Case in point:

I've spent some time trolling through the BSAC incident reports and what always amazed me was the number of injuries and fatalities that occur due to problems with dry suits.

I'm drawing my own conclusions. Y'all: DNFTT.

 

[MXGratefulDiver]

Apparently not if you talk with the major recreational diving agencies.

I'm curious how much talking you've done with the major recreational diving agencies ... or more specifically, with the people in them who are responsible for establishing the curriculum for their classes.

Can you enlighten us on what they told you about why they don't teach more comprehensive gas management in OW and AOW classes?

... Bob (Grateful Diver)

---------- Post added December 6th, 2013 at 04:15 AM ----------

I've spent some time trolling through the BSAC incident reports and what always amazed me was the number of injuries and fatalities that occur due to problems with dry suits.

... that would amaze me too, if it were true. It would indicate that BSAC has some serious deficiencies in their drysuit training. I've personally got thousands of dives in a drysuit, dive almost exclusively with other divers wearing a drysuit, issued dozens of drysuit certifications ... and I've not once ever known anyone who has suffered injury due to problems with their drysuit. That includes people who are using them inside of caves, wrecks, and below 200 feet. That would cause me to wonder why BSAC trained divers are having all these problems ...

... Bob (Grateful Diver)