OOA on the Vandenberg

[jgttrey]

Buddy up tight and ascend. Dont go to the octo until he's nearly empty. Initiating an air share prematurely is foolish.

It poses its own risks for one thing. If the other guy is that inexperienced and has incipient panic, he could fumble the switch, inhale water, etc. Now you've got a real problem - at 90', not 30 or 15. That's a fail. Period.

Moreover, if he's huffing that bad, then there's a risk he drains your tank, necessitating a double switch back to his remaining 700 psi - assuming he hasn't bolted for the surface by then and left you behind.

I'm sorry, I don't think there's a good argument for a prophylactic air share in that situation - and nobody teaches that.

Plus, you're judging all of this with 20/20 hindsight about his gas use. 700 psi is plenty to get most divers to the surface. Sure, this is one of those exceptions, but everything is better shallow. Grab on to him, control the ascent and switch when you need to - not before.

 

[MykaDives]

I would have offered my long hose around 500 psi (similar to OP), and been extremely persistent that he take it. I'd rather the LOA diver doesn't become an OOA diver because OOA adds a layer of complexity to many things (expected and unexpected), such as having to orally inflate on the surface. Will he remember that or will he panic when the LPI doesn't do anything? Maybe he does remember that, but he gets splashed in the face mid-breath and is choking/gagging and can't get a good breath to fill the BCD/wing (just one "unexpected" complication on top of the "expected" complication), now you have to try to get in there and do it for him when the moments are ticking closer and closer to panic. No thanks.

I also expect the hang tank valve to be turned off, and the system charged. Have valve turned on when entering the water, install hang tank, take a few breaths on it, check for leaks, turn valve off. If it is charged it will also help to keep water out of an unnoticed leak for double redundancy.

 

[gr8jab]

@Normal_life_is_just_SI, sorry if I sound cold or callous. I don't really mean it that way. If we were in person, I would express these thoughts through a tone of voice and body language as sincere curiosity, not a criticism.

This is a slightly different perspective than most of the other respondents.

You were an employee or a hired dive master? You were specifically assigned to be a DM on this dive? Or, you happened to become the instabuddy with the most experience? If the latter, why did you assume the roll of a DM, checking everyone's air multiple times and such, and attempting to offer air when none was requested? It seem to me that during this dive, you assigned yourself more authority and responsibility than a typical buddy.

Sure, you and your buddies should have a clear plan (and you did). You decided on a 'turn around psi' and who would lead and follow. That's logical. But, when and how did it become your responsibility to monitor everyone's air?

Maybe as a DM you should be tracking everyone's air, but how did you become elevated from a buddy to a DM? That's added responsibility (emotional and financial). Why not dive the dive as a good buddy, not a DM?

I blame the other guy. It is his responsibility to monitor his air. His responsibility is to signal the turn-around if needed. His responsibility is to act prudently if low-on-air. His responsibility is to stay close and ask for an octo if he goes OOO. Sure, a good buddy would do everything to help out, and provide assistance and such. But a buddy is not a babysitter.

Personally, I would be a little put out if my instabuddy started acting like my DM. I've heard several people avoid advertising their DM credentials just so they would have a normal dive, and not be expected to DM.

Again, I don't mean this in a callous way. I'm being a little extreme and acting in the devil's advocate roll just for conversation sake. I present this perspective as food for thought. I was not part of the dive briefing, so maybe this was the agreed upon hierarchy and I should shut up.

 

[johndiver999]

If the DM was diving 90 feet without any redundancy (which we can assume is the case because he did not mention otherwise) and is thus depending on this buddy to provide him air in an emergency, then he has a vested interest in making sure the guy has preserved enough air for BOTH of them to ascend from the dive. It is for his own self-interest that he keep a good handle on the guy's air supply - and he did that for the most part. He was never unaware of how much air the guy had.

Of course when he got low, that is one more reason to start sharing air early - you are effectively saving an emergency supply in his tank for YOU.

 

[jgttrey]

Of course when he got low, that is one more reason to start sharing air early - you are effectively saving an emergency supply in his tank for YOU.

No. This is backwards. You do not risk exhausting your own gas supply by prematurely donating your Octo when he has 700 psi left. That is nuts. Then you BOTH have to switch back to his remaining gas when he drains you? You are the non-stressed diver and you want to put yourself in the position of having to rely on the donee's remaining gas? You're also prematurely doing a switch with a diver of unknown ability at depth where the consequences of a botched switch are more serious and having to unnecessarily manage the ascent while sharing. You're also wasting time at depth going through gas more quickly instead of shallowing up. No, no, no. It's all bad.

Buddy up close, monitor his gas and ascend. Give him the Octo when he's at 100 psi or 200. By then, you're also shallow, where everything is lower risk if he panics. If it goes sideways at 30' he can CESA, go to the hang bottle or whatever. It may turn out he doesn't even need it.

What agency instructs that you should donate when someone has 700 psi left? That is just a bad idea.

 

[gr8jab]

If the DM was diving 90 feet without any redundancy (which we can assume is the case because he did not mention otherwise) and is thus depending on this buddy to provide him air in an emergency, then he has a vested interest in making sure the guy has preserved enough air for BOTH of them to ascend from the dive. It is for his own self-interest that he keep a good handle on the guy's air supply - and he did that for the most part. He was never unaware of how much air the guy had.

Yea, I'm not seeing this. You are suggesting they did gas planning for a 'rock bottom' profile. My calculations for that profile, using 90' depth and 40 psi/min SAC for both divers (under stress in an emergency) comes out at a rock bottom of 1415psi. That's the minimum pressure required to safely return two divers to the surface on one tank.

Your assertion then is in conflict with the OP's stated plan. Let me explain. They agreed to a 'turn around' pressure of 1800psi. But, see where that approximately leaves us:

Descend: consumes 300psi (tank now at 2900psi)
Outbound exploring to turn: consumes 1100psi (tank now at 1800psi)
Return to mooring from turn: consumes 385psi (tank now at rock bottom of 1415)
Ascend

Even with a good current, how can they go outbound for 1100psi, and hope to get back on 385psi. That's not logical.

Therefore, I claim that the OP did not plan for, and had no expectation of preserving enough air for both to ascend safely without risk of DCS.

Again, I say all this with a pleasant tone intended, hoping for a good conversation.

Of course when he got low, that is one more reason to start sharing air early - you are effectively saving an emergency supply in his tank for YOU.

Not how I would do it. I would let him suck it dry, and then share my octo.

Here's my rock bottom calculation:

 

[gr8jab]

Buddy up close, monitor his gas and ascend. Give him the Octo when he's at 100 psi or 200. By then, you're also shallow, where everything is lower risk if he panics. If it goes sideways at 30' he can CESA, go to the hang bottle or whatever. It may turn out he doesn't even need it.

What's the reason for 100-200psi? Are you worried sucking it dry would be stressful, or is there some other reason to maintain some pressure in the tank. I'm only asking because that's 2.5-5cf of air (or am I wrong). That's another 30 feet or so of ascent, isn't it?

Cheers!

 

[jgttrey]

What's the reason for 100-200psi? Are you worried sucking it dry would be stressful, or is there some other reason to maintain some pressure in the tank. I'm only asking because that's 2.5-5cf of air (or am I wrong). That's another 30 feet or so of ascent, isn't it?

Cheers!

Exactly. If it were me or a known buddy in the donee's situation, I'd suck it dry, or very close because I'm 100% comfortable with task of sharing. But with an unknown diver that may not have shared air since his open water class years earlier, no way I'm going to do it prematurely at depth or wait until he sucks it totally dry and he freaks because his lungs are empty and he forgot how to purge or something. Once I get to the point that I know he's going to need to share, I'd rather do it in a controlled and deliberate way with his lungs full of fresh gas and my Octo right in his face.

So, I'd keep him on his gas, grab his bcd strap as if we were sharing and ascend, controlling the situation. When his gas gets low, say 100 psi, then we can pause and donate at our leisure - hopefully when we're at 15' rather than 90'

If course, we've had days to contemplate this, so I'm not trying to be too harsh on OP who had to decide on the fly. I just think this is the best practice.

 

[BlueTrin]

What's the reason for 100-200psi? Are you worried sucking it dry would be stressful, or is there some other reason to maintain some pressure in the tank. I'm only asking because that's 2.5-5cf of air (or am I wrong). That's another 30 feet or so of ascent, isn't it?

Cheers!

I don’t like the idea of the OOA diver unable to inflate his BCD except orally

 

[Aviyes]

I don’t like the idea of the OOA diver unable to inflate his BCD except orally

Why? It is a required skill that is a part of most if not all agencies OW certification training.