Rock Bottom Gas Management - A Hypothetical Accident Study

[O-ring]

What do some of you think is an appropriate gas plan for a novice on a recreational dive?

Be back on the boat with 800 psi?

What other skills do you think are required to ensure the effectiveness of the plan?

Regularly checking SPG, not straying too far from the anchor line so he/she/they don't get lost, proficiency with compass so he/she/they don't get lost (if no compass proficiency then staying within a visual of the anchor line or guided dives only).

Why so basic? Well, my experience with novices is that if you give them too much or too many things to worry about the whole thing turns into a charlie foxtrot of epic proportions (including AOW people). I say stress a few important points and maybe they will remember/follow them..

 

[JamesK]

O-ring once bubbled...

Be back on the boat with 800 psi?

I agree, but how do they know what amount of gas to ascend with so they have 800psi left.

My personal feelings is that they should stay above 60ft, and that they should be back at the ascent line, or starting their ascent with over 1000psi each. Not even "MegaMaid" (Spaceballs) can suck down 500psi in what would be about 5-7 minutes in shallow water. that way they have enough for each diver in case of an emergency on ascent.

 

[O-ring]

starting their ascent with over 1000psi each

That's kinda what I was thinking with the "back on the boat at 800" thing...that way they would start ascent really early.

 

[JamesK]

O-ring once bubbled...


That's kinda what I was thinking with the "back on the boat at 800" thing...that way they would start ascent really early.

 

[landlocked]

MikeFerrara once bubbled...
What do some of you think is an appropriate gas plan for a novice on a recreational dive?

100 lbs for each 10 feet of depth plus 500lbs for the boat. Therefore, at 60 feet they start their ascent when the first diver nears 1100 lbs of air. That should work until they gain more skill and training. You can trash PADI and SSI and NAUI etc. all you want but they do teach simple techniques that will get you safely out of the water if you apply what they teach. More advanced diving and techniques come later with more practice, skill and training. In every case of injury that I have read or heard about, there have been at least one concept that I learned in my OW class that was violated or not followed. This hypotetical case had at least three. What were they?

 

[roakey]

Genesis once bubbled...
The primary flaw was having Jane dive a SMALLER cylinder.

IF Jane insists on doing so, then Dick's only defense is for HIM to have his own redundancy, because while Dick can provide Jane with redundancy in the situation posited, Jane cannot provide Dick with redundancy.

I think you need to reread my post.

Though having Dick dive the smallest cylinder is the most expedient solution, a solution other than swaping cylinders exists. Simply do a dissimilar cylinder calculation IF Jane “insists” on diving the smaller cylinder.

We do it all the time when caving, instead of the more problem-prone solution of playing musical cylinders that may put unfamiliar equipment on divers.

See: http://www.scubaboard.com/t11430/s.html

Roak

 

[Uncle Pug]

landlocked once bubbled...
plus 500lbs for the boat.

Your boat uses air?

 

[landlocked]

Uncle Pug once bubbled...

Your boat uses air?

Dosen't yours?

 

[Uncle Pug]

landlocked once bubbled...
Dosen't yours?

...that I supply...
Uncle Pug (the boat) has to get its own air...
(Normally aspirated diesel.)

 

[AquaTec]

JamesK once bubbled...


I agree, but how do they know what amount of gas to ascend with so they have 800psi left.

My personal feelings is that they should stay above 60ft, and that they should be back at the ascent line, or starting their ascent with over 1000psi each. Not even "MegaMaid" (Spaceballs) can suck down 500psi in what would be about 5-7 minutes in shallow water. that way they have enough for each diver in case of an emergency on ascent.

I was wondering when someone would bring up the dissimular tank, dissimular sac rate calculations for turn pressure. it emphasizes the fact that there is more and more top learn when you want to use the rule of thirds, which i believe is way beyond the scope of entry level divers.

the rule of 500 for the boat, a simple calculation to use would be

Tank pressure = 3000psi
for the boat = 500psi
ascent gas = 300psi
Total = 800 psi

so 3000psi - 800psi = 2200psi

1/2 the gas out and 1/2 the gas back = turn pressure of 1100 psi
who ever reaches that first turns the dive.

you can change any of these number to suit your style but the math is on an entry level bases [if you want 800 on the boat then insert that number appropriatly]


if eather diver has an ooa situation then they should make a direct ascent to the surface, at the entry level task loading in this situation is a major problem, [one reason they stopped teaching buddy breathing] someone who has 10 dives under their belt will be hard pressed to even do a 15 foot stop, if we teach them that they will get bent without it, then they will die trying to accomplish it.