Octopus free-flow at depth

[DA Aquamaster]

I am not familiar with all the acronyms, what is IP?

...I completely agree on being able to turn on your own valve. I am not that experienced, but I have already jumped into the water with the air closed.

...However, I am not completely convinced still that the best solution to the original poster's problem would be to close his valve unless he has managed to reach his buddy.

IP is Intermediate Pressure - on most regs it is between 120-145 psi above ambient pressure.

Jumping in the water with the valve off is one of the major reason you want to be able to turn your own valve. In the best of circumstnaces when a crew or DM gets the lefty-loosey/righty-tighty thing confused and turns off you gas it is very inconvenient if you cannot reach your own valve. In the worst case, if you are entering negatively bouyant, for example as you would do in a strong current, or perhaps if you just fell off the boat before your BC was inflated, it can be fatal.

If I feel or suspect that anyone has messed with the valves, I breathe off the reg and check the SPG to make sure the needle did not drop to ensure I still have gas before I step off the boat. This is because I also wear a dry suit and if you go in negative with no gas and cannot inflate the suit, the squeeze may prevent you from reaching the valve(s) even if you normally can. So you keep going to the bottom with no gas and the odds are good that you are gonna die. Technical divers die this way on an occassional basis.

Also, it is not uncommon for a valve to be only partially open. It may breathe great at the surface, but at depth you can't get enough gas. Being able to turn on yourr own valve makes this a non-event.

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No one was suggesting the OP turn his gas off before he reached his buddy and completed the air share.

 

[Rick Murchison]

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A ScubaBoard Staff Message...

Leash/Buddy Line discussion moved here.

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[stadevene]

There is good information in this thread, thanks Hintermann for starting it off. From DA's comments I got thinking more about regulator checklists and what I should do. I was also unsure of the term "vacuum check" but after a quick board search I came across this excellent thread which explains all:

http://www.scubaboard.com/forums/regulators/260452-regulator-checklist-inspection.html

Post #7 has a quote of DA's reg check which is something we should all probably take more care in understanding and following.

Cheers.

 

[merxlin]

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A ScubaBoard Staff Message...

Please keep to the original topic and remember why this forum is here- which is to learn from diving incidents and hopefully keep anyone else from repeating the cause of that incident. You may disagree on things, but keep the discussion civil.

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[gerard2004]

I'm a little surprised there hasn't been more discussion in this thread advocating for redundant air? I'm a new diver but as i'm learning, getting a pony bottle is appearing like a very worthwhile thing to do. In the event of a full free flow, or first stage failure, I should still have enough to surface WITHOUT having to rely on a buddy. I guess the main question is, other than cost and a little more bulk, what's the downside to having a 13 cu ft pony bottle?

 

[Leejnd]

There are lots of discussions throughout SB about pony bottles. And like so many things about scuba, there are many widely varying views.

Here's a brief article I read once about pony bottles, that gives an opinion about the downsides of pony bottles, and who should/shouldn't use them: Click here

You can probably go to either the Basic or Advanced diving forums and search on "disadvantages of pony bottles" and get lots of opinions there as well.

 

[gerard2004]

Thanx for the article. Really just confirms what I thought. Cost and weight/size really are the only downside. I've read in other posts how someone would rather rely on his "buddy" than a pony. Guess I just don't get that logic. There are times I'm going to be going on charters diving with buddies I don't know that well. My first few dives have already been with people I've never dove with before. Why would I not want to be able to get myself out of a pickle on my own instead of relying on someone I don't know that well? I also forsee doing some shallow diving at some point on my own. In that case I would not even consider doing it without a pony. And when you consider the alternative, I guess the $400 price tag isn't REALLY that expensive!

 

[hudson]

What that article doesn't help with is the sizing. You really have three options: 13, 19 and 30cuft. If you are going to travel with the pony, 30cuft is pretty much out. So between 13 and 19 it comes down to this:
1) With 13 cuft you'll usually have to skip the safety stop, depending on your initial depth - not really a good idea on a stressed ascent from depth since you could be ascending faster than normal.
2) 13 cuft pony needs to be kept topped off - which means very frequent refills since you need to test it predive and it'd be a good idea to test it at depth as well, at least occasionally.
3) 13 cuft probably won't get you up from below 100ft.

 

[gerard2004]

I was thinking about the 13. Wouldn't consider smaller and if I went solo diving I'd stay shallower. As far as the safety stop, I suppose if I were in an air out situation, couldn't reach my buddy, I'd just have to risk a quick ascent and hopefully a minor case of the bends. Still better than the alternative. I'd have to take a look at the 19 and see what the size looked like. I think this also makes you a safer buddy since if you're both diving deep and using air at the same rate and getting close to turn around, then you get a bad free flow, you're buddy might be a little tight on air too and trying to get both of you up on one nearly depleted tank would be a lot easier if one of you were sucking off a pony!

 

[Rick Murchison]

Here's a table you may find useful in making a pony bottle selection.
The table shows how much gas you need (in CF) for a direct ascent to the surface (no safety stop) at 30 fpm, depending on depth and surface consumption rate in CFM.
As an example, my normal ascent SCR runs about .45 CFM, but I know from experience that my "max excitement" SCR can run as high as 3 CFM! So on a "normal day," a 13 is just fine for any NDL recreational dive, but throw in a little excitement... that 40's lookin' mighty nice
Rick