How much air to surface with?

[dmaziuk]

NOPE ... on a recreational dive it is EXTREMELY unlikely that a CESA from 80 ft will get you bent.

Some day I'll buy and actually read the book... might even understand it.

 

[scubadada]

Such a lot of debate over what is really a simple answer - regardless of tank size.

Recreational divers are to be back on the boat with 500 psi because that is the only thing the boat can easily measure!

....or not, almost nobody asks or checks (or keeps a log like Mel!)

 

[AfterDark]

Some day I'll buy and actually read the book... might even understand it.

My 1st and only real life CESA was from 70FSW no bends. I exceeded the then recommended 60' per min ascent rate but I didn't drown. No matter how long a drowned diver is in a chamber they are still dead.

A diver either has too much N dissolved in the blood to ascend non-stop or not, SS are optional. No one ever got bent by blowing off a SS on an NDL dive that I know of.

I surface with air in my tank. If I'm diving a charter or somebody's boat and they want an amount, I'll surface with that number which always seems to be 500psi. Fills are too expensive to surface with more, IMO.

I should add one thing here, I don't use an octo, I sling a pony or dive ID's, so I always have a redundant air supply at hand.

 

[geoff w]

Wonderful idea. That way nobody really has to think...

Don't mistake recreational divers on a guided underwater tour with competent, responsible divers. There's often a big difference. On a lot of boats where the DM says be back with 500 PSI, chances are a lot of divers haven't been diving for a long time and can suck through a tank in no time. I've seen divers surface because they got down to less than 500 PSI in less than 15 minutes in warm tropical water, not on a deep dive If you do vacation dives, ever notice how usually there aren't many divers in the water at the end of your dive? Not every location and not every operator, but usually. Why would any dive operator not tell guests to be back on the boat with at least 500 PSI? They're not saying that for the benefit of experienced divers

 

[redacted]

Don't mistake recreational divers on a guided underwater tour with competent, responsible divers. There's often a big difference. On a lot of boats where the DM says be back with 500 PSI, chances are a lot of divers haven't been diving for a long time and can suck through a tank in no time. I've seen divers surface because they got down to less than 500 PSI in less than 15 minutes in warm tropical water, not on a deep dive If you do vacation dives, ever notice how usually there aren't many divers in the water at the end of your dive? Not every location and not every operator, but usually. Why would any dive operator not tell guests to be back on the boat with at least 500 PSI? They're not saying that for the benefit of experienced divers

If you treat people like fools, you need to expect them to be fools.

Because a dive operator should know that a slow ascent and good safety stop are much more important than 500psi in the tank at the surface.

 

[NAM001]

WFIW

i dive under the premis that my spg is 10% off and not in my favor. It is part of hte 500 psi. so you need 150 psi for the reg to work properly and 10% of the tank is about 300 psi. So yo need 450 min psi in case your gage reads 300 too high. NOw think about all the gear you rent and are trusting with you life to be good. Any gage is only accurate in mid range readings. It is always a good idea to check you psi with other than what you are diving with and compare the gage you will be using to it. I fill tanks at home and mark the psi on it after a long cool period. fill at night . check the psi in the morning and head for the dive site. all who use my tanks check their psi and compare to what is on the tank. You may be surprised how much things vary. If there is a difference we put on another reg with an spg that is trusted to determine which gage is off.

 

[AfterDark]

WFIW

i dive under the premis that my spg is 10% off and not in my favor. It is part of hte 500 psi. so you need 150 psi for the reg to work properly and 10% of the tank is about 300 psi. So yo need 450 min psi in case your gage reads 300 too high. NOw think about all the gear you rent and are trusting with you life to be good. Any gage is only accurate in mid range readings. It is always a good idea to check you psi with other than what you are diving with and compare the gage you will be using to it. I fill tanks at home and mark the psi on it after a long cool period. fill at night . check the psi in the morning and head for the dive site. all who use my tanks check their psi and compare to what is on the tank. You may be surprised how much things vary. If there is a difference we put on another reg with an spg that is trusted to determine which gage is off.

Up until my last dive I used the same SPG for 30+ years,so I got to know it pretty well. It gave it up on dive 2051 last week. I'm not saying it was on the money but if it was off it was in my favor. It did go to 0 one time post dive in the shallows <10fsw but I still had air. I'll miss that SPG but I think I found one like it lightly used. Even though I use LP tanks I only use 5000 psi gauges which puts the needle about mid gauge so I start at the most accurate spot on the gauge, at least that is the theory.

Renting gear; I rented a camera once but never in 45 years of diving have I rented anything else. I'll ship my gear if I can't drive somewhere that I want to dive. IMO renting gear is where trouble starts, strange dive location, strange gear, maybe a different language or two a good mix for trouble IMO. As you posted "You may be surprised how much things vary".

 

[Zeagle Eagle]

In the setup on my Atomic Coblat, it says reserve 300 psi. I have looked din the manual and can't seem to find an answer. Does that mean when the Cobalt reads zero psi I have 300 psi left?

 

[redacted]

In the setup on my Atomic Coblat, it says reserve 300 psi. I have looked din the manual and can't seem to find an answer. Does that mean when the Cobalt reads zero psi I have 300 psi left?

Why don't you put it on a tank and find out?

 

[AfterDark]

In the setup on my Atomic Coblat, it says reserve 300 psi. I have looked din the manual and can't seem to find an answer. Does that mean when the Cobalt reads zero psi I have 300 psi left?

It could be, or you might have 100psi maybe 75psi could be there's 400 psi or maybe the tank is empty. Until you do some comparing there's no way to know, each gauge is a little different than even another of the same model!