Rule of Thirds & Shallow Rec diving

[Foxfish]

So that means you're either bent or dead. Congratulations. Twenty seconds worth of effort is keeping you and your buddy from going home safely tonight. THAT is why your methodology is so woefully insufficient. I love my wife, and I agree to care for my buddy when we buddy up. I don't want anything bad to happen to him, and I want to get to see my wife at the end of the day. When my wife is my buddy, it's even more serious. THAT is what's wrong with your strategy....if something goes wrong, it will ALL go very wrong.

To put the matter in perspective, we're quibbling over a few bar to cover a scenario that to the best of my knowledge has never been reported. In contrast BSAC records there have been dozens of incidents caused by problems with drysuits including fatalities. People still dive in drysuits and tell me they don't consider advanced training is a requirement.

 

[gcarter]

To put the matter in perspective, we're quibbling over a few bar to cover a scenario that to the best of my knowledge has never been reported. In contrast there have been dozens of incidents caused by problems with drysuits including fatalities. People still dive in drysuits and tell me they don't consider advanced training is a requirement.

 

[GCullen94]

To put the matter in perspective, we're quibbling over a few bar to cover a scenario that to the best of my knowledge has never been reported. In contrast there have been dozens of incidents caused by problems with drysuits including fatalities. People still dive in drysuits and tell me they don't consider advanced training is a requirement.

Fox fish... The numbers we posted are to the point where YOU WILL RUN OUT OF GAS. It's not "just a few bar" and OOAs get reported all the time, so does running out in the ascent. We just try to manage the risk, you obviously are going to dive your way and safe diving to you. Hope you're still here when SHTF. I will not buddy up with someone who doesn't follow basic gas theory because if I have a problem, that's mine and their gas.


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[Foxfish]

We're going over old ground here fellas. Look at my previous posts for responses to the same tired arguments.

Incidentally, I haven't seen too many estimates of the pressure required to surface on a normal ascent from 30 m. Add that to 50 b to get the pressure you'd start with. If your air consumption was high, say 25 L/min then it should end up around 80 b which just happens to be about the amount you need for an emergency ascent.

 

[GCullen94]

Fox fish... THE NUMBER I (AND COUNTLESS OTHERS) HAVE BEEN SAYING IS THE MINIMUM GAS NUMBER. That's what WE WILL ALWAYS START OUR ASCENT AT from 30M. If we get down to 80 B and start our ascent and then 5M later have an issue it will be TOO LATE. That's why we start our ascent at the MINIMUM number. I don't know why you can't comprehend this. The minimum number changes on depth and tank size.


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[gcarter]

We're going over old ground here fellas. Look at my previous posts for responses to the same tired arguments.

Incidentally, I haven't seen too many estimates of the pressure required to surface on a normal ascent from 30 m. Add that to 50 b to get the pressure you'd start with. If your air consumption was high, say 25 L/min then it should end up around 80 b which just happens to be about the amount you need for an emergency ascent.

You fail to grasp the basics, just as you fail to answer direct questions. The "same tired arguments" are attempts to educate you on the basics, but your mind is made up that you are right and you are refusing to take in any information.

Sentence #1: If you had read and actually understood what has been posted over and over, you would now be aware that this differs according to individual breathing rate and the nature of the dive. A normal ascent is different, for example, if you are going vertical to the surface or if you have to go diagonal to remove yourself from danger such as when you are in a shipping channel. THIS IS WHY RULES OF THUMB ARE BAD. One number DOES NOT fit every individual, every buddy (whose consumption ALSO is part of your concern when diving buddy pairs), or every dive. THIS IS WHY ROCK BOTTOM AND SIMILAR CALCULATIONS EXIST.

Sentence #3: YOUR BREATHING RATE WILL BE DIFFERENT IN AN EMERGENCY THAN IT WILL BE ON A NORMAL ASCENT. Air requirements in an emergency ARE DIFFERENT than they are for a normal ascent. Regardless of who you are. Your requirement for a normal ascent WILL BY DEFINITION NOT BE THE SAME as your requirement in an emergency.

 

[GCullen94]

Thank you gcarter for putting that better than I could. Foxfish, your breathing rate will go up in an emergency... think about BOTH divers breathing at 25-30L per minute?? thats 50-60L per minute draining out of whoever's tank is being used. THAT IS WHY WE GET MUCH HIGHER NUMBERS.

 

[Foxfish]

Okay so forget about minimum gas and gas reserves for a moment. What pressure or what is the pressure change to ascend from 30 m to the surface on a normal dive with an air consumption rate of say 25 L/min. Other parameters to be as noted in post # 243 ie. allow for safety stop at the given depth. I suggested as part of the exercise back in post # 236 but some of you seem to have missed that or are having trouble understanding the intent.

 

[GCullen94]

Ok fox fish I'll do the calculation but remember, this leaves you our your buddy SOL when bad things happen. By the way, this is a version of min gas. You use the same calculation.

4ata x 25 = 100 L
2.75 x 25 (x3)= 206 L
1.5 x 25 (x3) 113 L
1.25 x 25 (.5) = 15L

total gas= 434L

In an 11L (AL80) that is close to 40B used on ascent for a lightly stressed, SOLO breathing rate... HOWEVER THIS ONLY USES ONE DIVER... add another diver and consumption would go UP! also more likely to be around 30L minute PER DIVER.

In a 12L=36B used on ascent for a lightly stressed SOLO breathing rate... If something were to go wrong at depth, there is simply NOT ENOUGH GAS to get you and your buddy to the surface using your method fox fish. It does all fine and dandy getting yourself to the surface with 50B if nothing goes wrong but doesn't leave ample reserves for your buddy.


WARNING: DO NOT USE THIS, THIS DOES NOT LEAVE ENOUGH GAS TO GET TWO PEOPLE HOME!!!

 

[gcarter]

Okay so forget about minimum gas and gas reserves for a moment. What pressure or what is the pressure change to ascend from 30 m to the surface on a normal dive with an air consumption rate of say 25 L/min. Other parameters to be as noted in post # 243 ie. allow for safety stop at the given depth. I suggested as part of the exercise back in post # 236 but some of you seem to have missed that or are having trouble understanding the intent.

My doing math for you does not help YOUR understanding of why this matters - regardless your intent. I know why it is important, and I know how to do it. Demonstrating that numbers can be plugged into a given formula to get a result has been done numerous times in this thread. I don't care what answer you get to your parameters - they should only be important to YOU. My numbers are different, for me, for a given dive, and for a given buddy.

I am not interested in doing a monkey dance to solve equations for you. I am interested in ensuring that anyone else reading this thread does not buy into your distorted and dangerous view that there is a single number that works for every diver on every dive - 50 bar + 10 * depth. It's nonsense.