Out of Air

[PerroneFord]

In some diving, but in an easy rec dive that's usually overkill. A lot of dives like that people are piddling around under the boat or near shore by then.

So what happens if your buddy runs out of air or has a problem with his tank? So he's just screwed because you're just piddling in 50ft of water? And you don't have enough reserve for both of you to make an exit with a safety stop?

The last third of that tank belongs to your BUDDY in case Murphy strikes. Of course no one tells you this in OW class.

 

[lairdb]

So what happens if your buddy runs out of air or has a problem with his tank? So he's just screwed because you're just piddling in 50ft of water? And you don't have enough reserve for both of you to make an exit with a safety stop?

The last third of that tank belongs to your BUDDY in case Murphy strikes. Of course no one tells you this in OW class.

Hmmm -- how do you get that? Unless my calculations are all goofed up, at 50 ft, assuming 2cfm SAC (two divers, agitated but not panicing) and a 30fpm ascent rate, you need 5.8 cf for direct ascent, or 14.6 cf with a full three minutes at 15ft.

From 25 feet (which is more what I'd think of as "piddling around" depths). the same two divers, even ripping a full 3cfm, but holding their ascent rate down to 15fpm, still need only 6.9 cf for direct ascent.

All that said, no-one tells you about rock-bottom in OW class either.

 

[PerroneFord]

How do I get what? Rule of thirds? You don't need to understand rock bottom to understand the fact that if things go wrong, and I had planned on bleeding my tank dry, I may not have enough to save my buddy. It's the actual revelation of actually THINKING about the buddy that's on my mind here. Not the actual gas plan.

Of course your numbers didn't include the time at nearly 3ATA to try to sort the problem, nor did it account for perhaps an inaccurate gauge, like the time a famous cave diver told me he sucked his tank dry with 200psi (in doubles) still showing on the guage.

 

[CoyKoi]

Nice job keeping your head, Pietfer. I've stared panic in the face only twice while diving and had to mentally talk it back down into a place where it couldn't hurt me. Its a frightening, sharp-fanged monster that only you can control. Once it sinks its teeth into you, you're dead.

Get your own reg set and computer and take them with you on every dive trip. They don't take up much room. I always pack mine in my carry on. I can dive without my clothes and cosmetics if my luggage is delayed -- but not my reg. The rental gear is fine for OW students doing their check out dives, but IMHO it has no business hooked up to a 'real' diver. Its not SCUBA equipment, my friend, its life support equipment. That said, there is no guarantee your own gear will never fail, but at least you know how its been stored and cared for. Equally important: have your reg set serviced regularly by a reputable dealer or dive shop.

My $.02

 

[tzeyap]

Tx all, I now realise (and agree with Dandydon - this is a red flag) that Scuba and gholf has a lot in common, NEVER CONSIDER YOURSELF AS "EXPERIENCED".

An OOA situation is something which any diver can find themselves in; whether experienced or not ; own equipment or rented.

I have just returned from a week of diving. My buddy and I had the services of a very experienced divemaster (paid). On one dive, we were doing a strong drift dive (5knots -no kidding !!). At one point, 20 metres down and about 30 minutes into the dive while we were hiding behind a rock watching the fishes being tossed up and down in the current, the DM calmly took hold of my guage and looked at it. He . then gave me the OOA sign. I gave him my alternate, and the 3 of us just held tight to each other; ascended and did the safety stop before surfacing.

Now this DM has 12 years experience as a DM and clocks up between 600 to 1000 dives a year !! It seemed that he had a slow leak in the tank valve and coupled with occasional free flow in the current; all of which led to his running out of air.

An OOA situation is one which should not happen but does. The most important thing is not to panic and think. Apart from securing air supply for both, the other critical requirement is to control bouyancy while ascending.

 

[TSandM]

I just want to make the point that calculating thirds is only necessary when you are doing a dive where you MUST return to a given point -- the exit of a cave, or the anchor line up to a stationary boat. When return is convenient but not necessary, you can dive halves, and when you can surface wherever you want (live boat pickup) you can use all the air above your reserve.

 

[PerroneFord]

Diving thirds is also applicable when you have surfacing obstructions (diving in a channel), or deco to worry about. As I said, the particular gas plan is not the worry here, its the LACK of a gas plan that's the worry. Particularly the lack of a gas plan that assists the buddy.

 

[TSandM]

As you know, PF, we are in complete agreement about that. I was just addressing CraigDiver's comment that you should surface with a third of your gas.

 

[gcbryan]

As far as I can tell the only person who had a lack of a gas plan was the person who posted that he starts to ascend when his tank gets hard to breath.

We don't know anything about anyone else's gas plan. I would be interested to know what the SPG read when the original poster realized he was out of gas.

 

[CraigDiver]

As you know, PF, we are in complete agreement about that. I was just addressing CraigDiver's comment that you should surface with a third of your gas.

Here in the UK, under BSAC, we are trained to always return with a third of our air left as a reserve irrespective of the type of dive. But we do seem to be over cautious!