32 replies to this topic

[Greg@ihpil]

I would only add:
Thats why I think this site is a benifit to all,in a variety of scenarios.It's D--- good information!!
Hope I don't have a OOA.But at least I have some good pointers to heed & ones that I've practiced in the pool b/4 trips.

[peterbj7]

I guess that's one plus of having a wrist mounted air intergrated computer. Its a single look to see time, depth and air, including an estimate of minutes remaining. As long as I remember to look at it before every dive, I can catch such situations. I do have a connected backup pressure gauge, but the AI is a nice luxury if you can afford it.

I did have one once upon a time but wasn't keen and sold it. And once you use multi-gases it's no use anyway.

[Sharklover]

I've never come anywhere close to going OOA. But I routinely dive to the outer limits of recreational dive limits, so we are pretty careful with gas planning. I get on board here in NC with 1800 psi. I'm much more likely to push that in shallower environments.

One comment I wanted to add was the importance of buddy checks every dive and discussion of air sharing in an OOA emergency with any new dive buddy.

A lot of us here at home are used to donating our primaries. We need to tell our buddies that on the boat. For buddy checks we typically stop at the hangline under the boat at 15 feet, or if I am in the Caribbean, as soon as we reach the bottom before we take off from the boat above us, and check our buddy over and give each other a chance to make sure everything is working properly and to get sorted out. MANY TIMES when using rental tanks there has been a lot of bubbling from my buddy's tank, or mine, due to a bad o ring or something.

[georoc01]

I guess that's one plus of having a wrist mounted air intergrated computer. Its a single look to see time, depth and air, including an estimate of minutes remaining. As long as I remember to look at it before every dive, I can catch such situations. I do have a connected backup pressure gauge, but the AI is a nice luxury if you can afford it.

I did have one once upon a time but wasn't keen and sold it. And once you use multi-gases it's no use anyway.

I guess it depends on your computer and how much you spend on transmitters. Mine supports up to 3 gasses.

[peterbj7]

Yes, but the problem of managing the computer quickly becomes overwhelming. I'd much rather glance at a gauge every once in a while. A few other points. I know of people who have found themselves looking at the pressures in tanks being used by close neighbours, don't know how common that is. I have had dives blighted by computers complaining that they've lost the signal from their transmitters. These things are electronic and need batteries, and it's all too easy to forget to replace them. And I have several times seen transmitters broken or sheared off from their regulators. All to avoid glancing at a gauge - not for me. The simpler my equipment when I'm diving, the less likely it is to fail.

[WreckWench]

I guess that's one plus of having a wrist mounted air intergrated computer. Its a single look to see time, depth and air, including an estimate of minutes remaining. As long as I remember to look at it before every dive, I can catch such situations. I do have a connected backup pressure gauge, but the AI is a nice luxury if you can afford it.

It is a nice luxury but not as reliable as I wish they would be as sometimes the wireless does not make good connection with the sending unit, or tells me I don't have air in the tank, etc. If you dive one you really do need to have a back up pressure gauge and a back up non-air integrated computer, otherwise you will have to use tables to complete your dives or sit out if/when your air integrated computer acts up.

[shadragon]

I have said for many years that SAC rate is mis-leading. Your SAC rate changes from breath to breath and depends on where you are, what you are doing, your work load and mental stress levels.

On two seperate occasions, I have burned through 2000 PSI in three minutes and also spent an hour and fifteen minutes at depth. Both times on an AL80 with the same starting gas volume. SAC is a great theoretical exercise. However, knowing how much gas you need to get safely to the surface only comes with experience.

Do plan the dive and dive the plan. But when the plan goes awry, thumb the dive. Nothing else matters but your safety.

[Sharklover]

I have said for many years that SAC rate is mis-leading. Your SAC rate changes from breath to breath and depends on where you are, what you are doing, your work load and mental stress levels.

On two seperate occasions, I have burned through 2000 PSI in three minutes and also spent an hour and fifteen minutes at depth. Both times on an AL80 with the same starting gas volume. SAC is a great theoretical exercise. However, knowing how much gas you need to get safely to the surface only comes with experience.

Do plan the dive and dive the plan. But when the plan goes awry, thumb the dive. Nothing else matters but your safety.

True enough. My SAC rate is the envy of many. But I carry an AI computer and a backup gauge at all times. Generally, when the conditions are similiar, it is simply a perfunctory exercise. Especially here at home where I hit my NDL when I have more than half of my tank remaining. But if conditions are challenging, such as one dive while I was in the Maldives when we were swimming against very strong current, I was all over my gauges and all of us had to ascend well away from our intended ending point due to air supply despite what was a good plan at the outset.

[grim reefer]

It is easy to get complacent, especially on easy dives that we've done a million times before. I too, can't remember the last time I had less than 1000 psi in my tanks.

My predive checks include observing the pressure gauge while breathing several times from both regulators on the surface, verifying that the valves are open, etc. This prevents me from jumping in with the air turned off or partially open. Once in the water (at the 15 ft hang line/bar in NC) I check my gauage and do another flow check. My buddy and I look for bubbles coming from each other, give the OK and proceed. At the bottom I make another flow and pressure check and then every 5 minutes after that. Because I have practiced it so much it's all automatic and takes negligible time and effort. I don't have to pause what I am doing. It's just like checking the mirror and the speedometer and other gauges while driving. I remember when I first started driving how much effort it took to do all the tasks and diving is really no different. Time in the saddle and the development of a routine and muscle memory make all the difference.

I have never run low or out of air but I have experienced an OOG. It was several years ago and I had about 3500 psi in my tanks when it happened...

Once while decending the anchor line during my advanced nitrox class I was at about 50 feet when I took my last breath. The plan was for the instructor to tie in and then me to follow 5 minutes later. I was the only student in the class, so I was solo and there was no buddy to turn to. Honestly, my first thought was to go for my O2 regulator. Yikes!!! Next thought was to bolt. Then I calmed down and reached back and turned my valve back on. Ahhh. I could breath. I looked around to see if my instructor was messing with me. Nope. He was down at 110 ft tying into the wreck and nobody else had splashed yet. I knew I had checked the valve up top before rolling in. It was only then I realized that I had had the anchor line underneath the valve knob as I was decending and the friction had closed the valve.

Lessons learned: Don't panic. And be extra careful when swimming under lines! It's best not to do it at all if you can help it. Also, since I was diving doubles I really should have switched to my backup reg after verifying it was operational, which it was. All the right post problems I had visualized before the dive involved free flow, or leaks so it threw me off my game.

Edited by grim reefer, 13 February 2012 - 01:34 PM.

[peterbj7]

[quote name='shadragon' timestamp='1329146930' post='296598']I have said for many years that SAC rate is mis-leading. Your SAC rate changes from breath to breath and depends on where you are, what you are doing, your work load and mental stress levels/quote]

I'm not sure I'd use the term "misleading", though I agree with your sentiment. If you study the evolution of S&R as a discipline you'll see that a number of well-meaning divers have died on what they thought would be straightforward operations. They didn't realise that when under physical or indeed mental stress your air consumption can easily increase 7-fold, and cases have been recorded when it has risen 15-fold. Under those conditions, a tank that would normally last you an hour will be empty in just 4 minutes. The problem is inadequate training, at agency level. Even though I was already a technical dive instructor with several thousand dives, I didn't realise the full enormity of this until I went on a course to become a S&R diver and then instructor. The numbers I've given above aren't vague estimates, they're actual measurements under test conditions.

[dive_sail_etc]

I've never come anywhere close to going OOA. But I routinely dive to the outer limits of recreational dive limits, so we are pretty careful with gas planning. I get on board here in NC with 1800 psi. I'm much more likely to push that in shallower environments.

Returning from a typical NC offshore dive with 1800psi is pretty darned impressive! My consumption rates are similarly stingy; perhaps we will buddy up if ever on the same dive trip.

One comment I wanted to add was the importance of buddy checks every dive and discussion of air sharing in an OOA emergency with any new dive buddy.

A lot of us here at home are used to donating our primaries. We need to tell our buddies that on the boat. For buddy checks we typically stop at the hangline under the boat at 15 feet, or if I am in the Caribbean, as soon as we reach the bottom before we take off from the boat above us, and check our buddy over and give each other a chance to make sure everything is working properly and to get sorted out. MANY TIMES when using rental tanks there has been a lot of bubbling from my buddy's tank, or mine, due to a bad o ring or something.

I follow the same practice and it has saved many a potentially problematic and likely aborted dive. I wear the title "air leak Nazi" as a badge of pride.

[Sharklover]

I've never come anywhere close to going OOA. But I routinely dive to the outer limits of recreational dive limits, so we are pretty careful with gas planning. I get on board here in NC with 1800 psi. I'm much more likely to push that in shallower environments.

Returning from a typical NC offshore dive with 1800psi is pretty darned impressive! My consumption rates are similarly stingy; perhaps we will buddy up if ever on the same dive trip.

One comment I wanted to add was the importance of buddy checks every dive and discussion of air sharing in an OOA emergency with any new dive buddy.

A lot of us here at home are used to donating our primaries. We need to tell our buddies that on the boat. For buddy checks we typically stop at the hangline under the boat at 15 feet, or if I am in the Caribbean, as soon as we reach the bottom before we take off from the boat above us, and check our buddy over and give each other a chance to make sure everything is working properly and to get sorted out. MANY TIMES when using rental tanks there has been a lot of bubbling from my buddy's tank, or mine, due to a bad o ring or something.

I follow the same practice and it has saved many a potentially problematic and likely aborted dive. I wear the title "air leak Nazi" as a badge of pride.

Well in all fairness, it is a HP steel 100, and I am a girl. Though a tall one. It has been pretty good since the beginning, but I think I go into a meditative state in the water, I'm very relaxed. I am super careful about monitoring my supply when in current or rough conditions, because I have seen my SAC go to hell in a handbasket when swimming hard against current or dealing with underwater problem solving as I like to call it.

I'm an air leak Nazi. It's a good thing to be here. Or anywhere really. Though I have had a buddy (an instructor) who chose to continue a dive with a leaking first stage. We just agreed that I would trail her and we continued the dive and I kept my eye on it. It ended up being an awesome dive, the leaking was minimal, and she has gills too. Probably would not have made the same choice here at home.

Sure, love to buddy with similarly inclined folks!

[TexasDiver]

This was actual OOA, not to be confused with prior posted video of diver who had air but went for the DM's octo for some other, unknown, reason.

[georoc01]

I guess that's one plus of having a wrist mounted air intergrated computer. Its a single look to see time, depth and air, including an estimate of minutes remaining. As long as I remember to look at it before every dive, I can catch such situations. I do have a connected backup pressure gauge, but the AI is a nice luxury if you can afford it.

It is a nice luxury but not as reliable as I wish they would be as sometimes the wireless does not make good connection with the sending unit, or tells me I don't have air in the tank, etc. If you dive one you really do need to have a back up pressure gauge and a back up non-air integrated computer, otherwise you will have to use tables to complete your dives or sit out if/when your air integrated computer acts up.

WHile I do dive with a backup computer, mine anyways, the computer just shifts to a non ai mode if if can't connect to the transmitter on a tank. In fact, when we were in Australia, our DM dove the same computer, with no Air Intergration. You buy the transmitters seperately.

The backup computer is no different than if you dive a non AI computer and have it die. Your options at that point is tables, having dived with a backup computer, or staying out of the water for 24 hours and starting over on a new computer.

Heck, even tables can be a challenge if you lose your computer, after all, how many people document the info needed to reconstruct your diving profiles in multi level diving if they haven't been doing it from the start of their diving?