Air sharing on ascent

[Blackwood]

If using standard length octo hoses face to face and vertical is about the only way the hoses will reach.

It's been quite a while since I've worked with a standard length hose, so forgive my confusion...

how so? It seems like the length of the hose will only dictate hose close together you must remain, not what position you're in. If you can share air vertically, couldn't you both rotate your bodies to horizontal, the donor's valve and the recipient's head the axes of rotation?

Awesome illustration, hose length is the same in both pictures:

 

[george w]

My wife and I have practised the ooa shared accent many times. The weekend after the practise we were in the ocean at 70 feet. (long story) I ran out of air for real. Because we had practised this it was like we were just doing a drill. I told her I was out of air and she gave me her octo. We each held each others BC and started the accent, including the safty stop. Had we not pactised it who knows how it may have worked out. I cant stress enough how important it is to pratise this. Even for very experinced divers, pratise is a wonderful thing. Then hope to never need the skill.

 

[Teamcasa]

My wife and I have practised the ooa shared accent many times. The weekend after the practise we were in the ocean at 70 feet. (long story) I ran out of air for real. Because we had practised this it was like we were just doing a drill. I told her I was out of air and she gave me her octo. We each held each others BC and started the accent, including the safty stop. Had we not pactised it who knows how it may have worked out. I cant stress enough how important it is to pratise this. Even for very experinced divers, pratise is a wonderful thing. Then hope to never need the skill.

It is so much better to read this type of post here and not in the accidents and incidents forum.

 

[Deefstes]

Jeez, guys. Thanks so much for all the excellent advice. I'm not a big fan of diving in the quarry but now I'm actually really looking forward to our next session so we can go over the tips you gave.

Based on your tips I think the key mistakes we made were:
1. To start the ascent as soon as my wife had the octo in her mouth. I think we'll agree to a three step or four step (or however many steps) plan for this drill. In other words, break it down into small manageable components and not continue to the next step until we're both happy that the first step has been done properly.

2. We had no point of reference (like a SMB line or something) and kept "chasing the needles" (I like that expression).

3. Both of us tried to exercise control over our ascent and safety stop. In future we'll make a point of identifying one diver as the driver and the other one as the passenger. I can't imagine many situations where the passenger wouldn't be the OOA diver but I think we'll just find a hand signal or something with which to communicate that under water.

Again, thanks for all the excellent advice, I never cease to be impressed by the expertise I see on ScubaBoard. I think it should be a treat to actually see you guys in action

 

[String]

Its worth doing without a point of reference - in the real world an OOA is unlikely to happen next to a shot line and its unlikely you're going to want to send a DSMB up with a diver within 6" of your face who is OOA.

 

[TSandM]

String is right. Practice deploying an SMB as a separate skill; I think you'll find that it's not something you are going to be able to do while you are holding onto your buddy a few inches away, and trying to manage an ascent. We send up bags while doing air-sharing ascents all the time, but we dive a different equipment configuration and have different procedures, so that we have both hands free while sharing air. It's still a lot of task loading, managing an air-sharing ascent and deploying a bag.

Diving in relatively shallow depths (recreational) in the daytime, you always have some degree of reference for up and down. Up is where it's getting lighter; down is where it's dark At night, this becomes considerably more complicated.

 

[tflaris]

I'd like to get your thoughts and advice on air sharing during ascent. Let me start by explaining where I'm coming from.

This weekend my wife and I decided to do some skills practicing at the local quarry. We wanted to look at some basic trim issues etc. but also to do air sharing while doing a free ascent with a 3 minute safety stop at 5m.

What a disaster! We started our free ascent at 15m and as soon as my wife took my octo, she became a cork. I'm sure it has nothing to do with using my octo but just that she forgot to mind her buoyancy. I grabbed her by the fin and pulled her down and at the same time dumped all the air from my BC. We must have been at around 10m by the time our upwards movement stopped and I'm surprised that our computers didn't complain of ascent rate violations so it couldn't have been too bad. By now she's realised what happened and she dumped all her air as well and before we knew it, we were back to 15m.

After some heavy finning and air additions to the BC's our buoyancy was sorted. OK, so we started the intended ascent. Things seemed fine although I think it could have been better. We didn't really ascend steadily but rather bobbed up and down with a net upwards movement, probably not ideal but not catastrophic either. The same thing continued through the safety stop and our 3 minute stop constantly varied between 4m and 6m.

If this was a real life emergency I think we'd have survived, even without harm. However, in a real life emergency at least one diver will probably have been much more panicked and things could have been much worse so I think we'll go back and practice this again until we get it right.

Now, your help and advice please.

1. Throughout the exercise, we were in the vertical position. Sorting out our bad buoyancy would probably have been easier if were horizontal but in a real life emergency I'm pretty sure at least one diver will not remain horizontal. Your thoughts? What is a good position for an air sharing ascent?

2. Keeping on the topic of body position, I found that donating an octo made things pretty tricky. We had planned on grabbing each other's BC's with the one hand, facing each other but the awkward looping of the octo hose made that, well, awkward. So we ended up being almost side by side, her to my left. Again, what is the correct way?

3. Both of us kept a close eye on our computers throughout, mostly to keep a tab on our depth. We both had the same computer but even so, they didn't give he exact same readings all the time. So while she thought we we're at 5.4m, I thought we were at 4.6m (this is probably because of the 20sec sample interval). The thing is I'd be trying to get us deeper while she'd be trying to get us shallower or vice versa. Would it perhaps be a better idea for both of us to keep an eye on just one of the computers?

4. Would it not perhaps be a good idea for only one of the two divers (the one who is not OOA, ie. the donating diver) to manage the entire ascent? In other words, the receiving diver has only two tasks, keep the donated octo in your mouth and hold on to the donating diver's BC. The donating diver then makes sure the collective buoyancy is correct and manages the safety stop, monitors the computer etc.

What else can you gurus tell me? I think this might be a valuable skill to master and once we have this one down pat we'll move on to buddy breathing during free ascent with a safety stop.

Pratice using the rule of thirds. Divide your total PSI of your tank into 3 equal parts. Use 1/3 of the total PSI swimming out (always against the current unless it is a drift dive). At your pre-determined turn pressure head back to your starting point. You should use no more than 1/3 of your gas supply to return to your starting point and this allows for 1/3 of your air supply for emergencies such as air sharing, lost buddy, lost boat, etc and allow for a safe careful ascent to the surface after a safety stop.

Hope this helps.

 

[Rick Inman]

String is right. Practice deploying an SMB as a separate skill;

Actually, I think you were already practicing two separate skills together, and breaking them down might help.

Doing a "blue water" ascent facing each other, staying together, face to face (horizontal, hopefully), maintaining the same depth, moving together and holding together at 15' for three minutes - without sharing air, is a daunting enough task. Personally, I would practice doing that first, and then add the air share.

Like the others have said, good on you for practicing the drill!

 

[nolatom]

I did it once not as a drill but because a buddy was low on air at about 75 feet.

There was no problem with my recreational-rig gear, I offered and he took my octo and grabbed my left BC strap. Yes, we were a bit ragged on dumping air and ascending since it's not that easy to synchronize, but it wasn't a serious problem, we figured it out as we went. We made the safety stop, by which time my pressure was down to about 300-400, same as his; then we ascended and he used his primary as soon as we surfaced.

Was I just lucky?

 

[Soakedlontra]

I am a newly certified diver and I would like to practice air share with a controlled ascend with my buddy. Every time I bring up the subject he hesitates and shows some uneasiness particularly about the controlled ascent. He is fine in practicing air share but without ascending.

I think this drill has to be practiced fully not half way just sitting comfortably at the bottom.

What is the optimal depth to practice air share without putting ourselves in danger?

(During the classes we practiced our drills at a depth of about 20feet)