OOA after only a few minutes with a full tank at 17m

[Mike Walker]

I've had the exact same thing happen. It is definitely possible to get to a point where the valve is barely open but breathes fine at the surface (deep breaths watching SPG) but then has issues at depth. In my case SPG/transmitter pressure started bouncing a couple minutes into the dive. No OOA, but breathing was a bit more labored than normal.

It was an awkward/rough entry with a go-around/false start before we dropped. It's possible it was someone 'doing me a favor' that got things out of sync. I've always been particular that once my valve is on, it's on, even if I lose a bit of air to leakage in a long dingy ride or similar. That being said, there were also some leaky o-rings on both tanks that day so I may have broken my own rule....

Since that - and based on some reading here and elsewhere - I now leave valve fully open or fully closed. No turning it back a bit - a procedure that apparently is completely unnecessary with modern valves. If the valve is at a hard stop and the needle doesn't bounce it gives me better certainty of on or off.

 

[The Chairman]

Three deep breaths on Primary

Looking at your SPG while doing this would have discovered the problem. Normal: very little movement. Slightly open: needle sways back and forth.

 

[Miyaru]

...
We returned to shore and verified everything, turned out that my bottle had not been fully opened.
...

You just had the best experience! Your actions to resolve the situation were perfect: signal your buddy, use his air to ascend and investigate once you're at a safe place.

And I'm pretty sure you will now check before every dive that the valve is fully opened (without the quarter turn back, which was done in the previous century).

 

[JohnnyC]

Don't turn your valve back. Seriously, don't. Whatever reason you were told is invalid with modern valve design. It's not an acetylene bottle that you're gonna wanna slam shut while it's on fire..... Open it all the way then don't touch it.

Open your valve all the way. Check your SPG when you pre-breathe. Check your SPG during descent. Open your valve fully then don't touch it. Should I say it again? Any other techniques? Yep, get a different instructor. There's no reason any instructor in this day an age should be telling open water students to do anything with their valve other than open it all the way and leave it.

As an aside, the cases that call for otherwise don't belong in the basic forum.

And in case anyone missed it the first time, open your valve all the way and then leave it, do not turn it back a quarter, a half, a thirty second, any turn whatsoever. There's no reason we should be seeing posts with this type of failure on this forum. The fact that it is a fairly regular occurrence is distressing.

 

[seeker242]

Do any of you have any other techniques that could possibly help avoid this kind of situation.

Don't do the 1/4 turn back. With modern valves, that's completely unnecessary.

 

[Doc]

OP, when you did your three derp breaths at the surface, did you watch your pressure gauge? The needle should wobble if the valve is not fully open.

 

[The Chairman]

FWIW, I still turn my knob back a quarter turn and teach it that way to students. A valve all the off or all the on feel exactly the same. A valve a quarter turn off, feels "loose" and easily differentiated between all the way off. Yeah, I check all my students' tanks before we splash.

 

[TeamBubbles]

Scuba valves are a little like being pregnant - you either are, or you aren't - there's no part way about it. Turn the valve all of the way on or turn the valve all of the way off. I hate to disagree with The Chairman, but valves that are all of the way on or all of the way off don't feel the same. Remember the old saying "Righty, tighty; Lefty, loosey." A valve that is all of the way on will only turn to the right (toward off) and a valve that is all of the way off will only turn toward the left (toward on).

 

[Jeremy Williams]

This happens more often that most people would like to admit. Be it from “help” or “forgot” it amounts to the same. A visual check is a good thing.

Products

 

[Storker]

I still turn my knob back a quarter turn and teach it that way to students.

I don't back off a measurable amount, but I prefer to turn the valve back a small notch from "stuck on fully open". It's probably my OCD showing. Again.