When to donate air?

[inquis]

It's really pretty simple. You have enough gas to get two stressed divers to the surface (I.e., "Rock Bottom" gas). You have 2 options:
1) Watch the Morey and Lion Fish duke it out while breathing from my long hose, then safely ascend on your own gas
2) Miss the show (and cause me to miss it as well) as you safely ascend on your own gas

If I have significant gas beyond Rock Bottom, I'm not going to be selfish with it. Personal choice, I guess.

 

[DrWilliam]

It's really pretty simple. You have enough gas to get two stressed divers to the surface (I.e., "Rock Bottom" gas). You have 2 options:
1) Watch the Morey and Lion Fish duke it out while breathing from my long hose, then safely ascend on your own gas
2) Miss the show (and cause me to miss it as well) as you safely ascend on your own gas

If I have significant gas beyond Rock Bottom, I'm not going to be selfish with it. Personal choice, I guess.

I don't think it's that simple. My scenario is specifically a surprised and inappropriate loss of awareness LOA situation where you are below Rock Bottom gas supply but each diver has a personal supply adequate to complete a safe surface ascent. Do you donate beforehand or drain the tanks to near zero?

 

[inquis]

WHAT is the definition of Low On Air?

For me, that's below the amount needed to get me and my buddy safely to the surface, with a safety stop. This is, of course, depth dependent, so I might signal LOA based on the current depth, but be fine to hang out at a shallower depth. As an example, on a wall dive at 80 ft, I might signal, "I'm LOA", immediately followed by "Ascend to 35 ft".

However, this is hardly universal. Some will use LOA to mean they may need to share "soon". That means don't wander off and ensure your octo is functional/accessible.

 

[inquis]

My scenario is specifically a surprised and inappropriate loss of awareness LOA situation where you are below Rock Bottom gas supply but each diver has a personal supply adequate to complete a safe surface ascent.

Surface immediately. Below Rock Bottom, you are no good to your buddy.

However, that's not the typical scenario when a DM might share to extend the dive -- see @boulderjohn's prior description where the group ascent is initiated when a second diver gets low. This is in the DM's assessment, as they already stated the desired point of notification. It's not uncommon when 2 are getting low when the DM queries the group to reassign buddies and send both low-air divers up the DSMB line while the rest of the group continues.

 

[johndiver999]

I don't think it's that simple. My scenario is specifically a surprised and inappropriate loss of awareness LOA situation where you are below Rock Bottom gas supply but each diver has a personal supply adequate to complete a safe surface ascent. Do you donate beforehand or drain the tanks to near zero?

I think it is a good question and the appropriate response is situationally dependent and obviously somewhat subjective based on the donor's perception of the situation.

If you are sure both divers have enough to get to the surface safely and independently, then starting the process of sharing air is going to complicate the ascent and possibly delay it. In other words, if both have enough gas then they should never have to share air - even if one hits the surface with near zero.

If one diver is so low that it appears likely that an air share will have to occur sometime during the ascent (and the donor clearly has sufficiently supply) then I think it makes sense to start sharing air on the ascent and early in the process. If both divers are calm and capable, sharing air during the ascent should cause very little stress for either person.

If the LOA person appears very nervous, then the best solution is probably to begin the ascent immediately and get them as close to the surface as possible and then offer the gas when they seem calm enough to accept it.

Sharing early and saving air for BC and unforeseen emergencies on ascent makes sense, but if providing the air when deep is just going to compound the stress level, then it is probably better to avoid it until it is really necessary.

Also, the reality of the situation is that if a recreational diver ran the tank way down and is making a very low on air ascent and is (understandably) very nervous; when they get to 20 feet or so, they are probably NOT going to vent air, stop the ascent and do a safety stop. They are just going to go for the surface and be entirely uninterested in sharing air, even if it is offered.

 

[TMHeimer]

I think you're hitting on a significant point here. How many divers really practice gas-sharing ascents? I think the last time I attempted one was the GUE Fundies course. I think for most divers, the go-to recourse for a plain old LOA event should be to end the dive and ascend together normally, provided their gas planning says a normal ascent is still possible. In an ideal world, we would all keep well practiced in the skill of a gas-sharing ascent, but maybe that's a lot to expect?

I agree. It is a lot to expect. Same as my old lament of someone taking CPR every 2 years and figuring they are prepared. I figure an active instructor/DM would be well prepared to do the OOA procedure. But My guess is the average diver wouldn't. I've been diving only solo last few years. My OOA practice is once weekly going through the motions in my easy chair. And I'll bet that's a lot more than 99% of OW divers.

 

[DrWilliam]

I agree. It is a lot to expect. Same as my old lament of someone taking CPR every 2 years and figuring they are prepared. I figure an active instructor/DM would be well prepared to do the OOA procedure. But My guess is the average diver wouldn't. I've been diving only solo last few years. My OOA practice is once weekly going through the motions in my easy chair. And I'll bet that's a lot more than 99% of OW divers.

I'm hearing a LOT that reaffirms what I've discovered that majority of certified OW divers are hovering on the precipice of complete and total PANIC of running out of air and have no concept whatsoever of gas time remaining or comfort with sharing air or heaven forbid the dreaded CESA. And yes, this "be back on the boat" crap has probably resulted in divers doing a panicked out of control ESA when they had 600 psi at 30 feet.

 

[halocline]

True. BUT, on a multilevel dive it is possible, on nitrox, to be at 60 feet, be within NDL, and panic when you realize you're at 700 psi and are supposed to be on boat with 500 psi.

Someone that panics because they have 700PSI at 60 ft on an OW dive probably shouldn't be diving.

This whole conversation is getting a little pedantic IMO. It's obviously better to share air with someone BEFORE they completely run out of air. Nobody would argue against that, would they? Deliberately waiting until a diver has no air is nutty.

So unless you are arguing that, then the real question is when do you share air, i.e. how low on air are you talking about. And the answer to that, IMO, is as soon as a diver realizes he doesn't have enough gas to safely surface. It's the least stressful solution and retains gas in both tanks for buoyancy.

 

[happy-diver]

So everyone on the boat is hyper they're looking furtively at each other and with a bellow
the gatekeeper, parts the crowd, with the how many bar have you, to which the lies begin

I've always worked either side of the 50bar, or that is what I will tell the people here today
up down round and round I would swim half an hour left of bar, that lasts at three metres

So up I climb the dreaded ladder to civilisation or the boat full of noise to shout thirty bar
and be loudly admonished by the captain, attempt to explain, never to tell the truth again

You see so when everyone is dumb then you buy a bigger tank or comp and take more air
so up I can climb the dreaded ladder to civilisation, the boat full of noise, to shout 100 bar

and not run out even if you fall asleep and have to share the stuff with dumb diverstalkers

 

[steinbil]

I think you're hitting on a significant point here. How many divers really practice gas-sharing ascents? I think the last time I attempted one was the GUE Fundies course. I think for most divers, the go-to recourse for a plain old LOA event should be to end the dive and ascend together normally, provided their gas planning says a normal ascent is still possible. In an ideal world, we would all keep well practiced in the skill of a gas-sharing ascent, but maybe that's a lot to expect?

It's a lot to expect from the average tropical diver, I agree, and if they are uncomfortable with gas sharing it might be less risky to ascend without gas sharing to avoid a runaway ascent from depth.

However, OP sounds like a more serious and thoughtful diver than the average vacation diver, so for those more comfortable I would think it's better to commit to stay current with skills such as a gas sharing ascent and be prepared to do it whenever it would help the team/buddy pair.

On that note, I'll definitely add gas sharing ascents to the list of things to practice with my team, as I think I've only done it once in the last year.