Primary on right or left post?

[CaveMD]

Besides, you should check your backup occasionally.

Dive sidemount

[tflaris]

If the reg was in your mouth, you know it is working. If your back up sin't working, you can buddy breathe, until you figure out the problem. Besides, you should check your backup occasionally.

Yes. In addition you can you the left post for wing inflation which can identify a roll off sooner than later.


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I am here: http://maps.google.com/maps?ll=30.315931,-81.676309

[DiveTrain]

Primary on left post. If I have a rolloff I would like to know.

Of course, this is pretty much academic - I've only heard ONE first-hand encounter of a rolloff - add to that the fact that I have anti-rolloff handwheels and I DON'T do tight passage, such as bedding planes. It's unlikely I'll ever have a rolloff.

This subject was brought up several years ago. I too had this mentality of "If I have a rollof I would like to know about it" primary on the left shoulder post (in harness) configuration...along with "I'll know if I hit my valves".

I have since had a roll off which has changed my thinking considerably.

TFlaris and MHendry and I were at Peacock making a jump off the crossover tunnel into a smaller tunnel that pinches down to single file towards the end. We had just thumbed the dive and turned around. Needless to say we were in the "soup" having reversed our direction and going into the tunnel we just exited.

Real World Situation: Low vis, single file tunnel, farthest point from entry. Turning around to get to a buddy would have resulted in a zero vis setting and possibly a wedge situation. Not to mention the line is sketchy in this part of the cave. Of course this is the point that Murphy decided to give me my first and only roll off. Keep in mind I didn't feel at any time that my valves hit, but due to task loading I probably just didn't notice. Having a my primary take a crap at this point and in these conditions created a Pucker Factor that you can't possibly understand unless you have been there.

If you have never had a Pucker Factor situation let me explain: All common sense and problem solving skills immediately get flushed. Catastrophic Failure will be where you start your problem solving exercise. You will immediately check your gas supply which should be good right? It IS the first time you look at it. But believe me when your primary goes down you will constantly mess with your reg to figure out the problem. This will release the gas in the SPG hose. The second time you look at your SPG you will show no gas which will turn a Pucker Factor into a Mother Pucker Factor and will further reinforce the Catastrophic Failure paranoia which is followed by get the puck out of here state of mind. This is bad.

Actual Events: I switched to my backup, checked SPG and fiddled with regulator while swimming in the soup. I figured I could breath so I had gas but no clue as to how much. Turning around to signal a buddy would only turn a bad situation worse as there was no room to turn around. I swam a few hundred feet to a small breakdown room and elevated to the ceiling so my buddy's could swim underneath me so I could communicate that I was down a reg. We put me in the middle of our formation as I was originally at the front. Tony gave me one of his bailout bottles as we proceeded to the main line.

Once we made it to the main line - rational thought started to trickle back in and my problem solving skills increase dramatically. It didn't take me long to determine that it was a roll off and turn the knob back on. This is the ideal world we all envision ourselves when we solve these hypothetical problems or say "what we would do". The fact is we won't know what we would do because we don't know the environment we will be in if and when it happens. Avoiding an Out of Air situation should be the pinnacle of our decision making tree for gear configuration.

Creating an Out of Air situation to notify you of a possible Out of Air situation when there are other options for notification is wrong. Nothing will change my mind on this. I don't care who says what and in what manual it is written.

I now have my primary and long hose off the right shoulder post and rely on my SPG and inflator hoses to notify me of a roll off. Using your SPG and inflator hoses as a notifier of a roll off is not as immediate as using your primary but in my opinion is fundamentally a safer configuration.


My .02

Chris Gregory

Even though I quoted Sludge this is meant as a response to everyone.

[LiteHedded]

good thing it was you breathing that reg and not your buddy

[deepdiverbob]

Which is my left shoe? The one that sits to the left as they are in my closet, or the one that goes on my left foot?

The one that goes in your left fin, of course.

[kwinter]

I switched to my backup, checked SPG and fiddled with regulator while swimming in the soup. I figured I could breath so I had gas but no clue as to how much.

At the risk of offending everyone, I had an SPG on each first stage in backmount doubles and never saw a good reason not to. There's an isolator valve in the manifold for a reason. As long as its there to separate the tanks, it didn't make sense to ignore knowing the pressure in each one. Rolloff is just one reason it could come in handy.

Ken

[jxh2297]

I think most people figure that if one side fails they immediately call the dive and head for the exit, so basically get out asap and knowing pressure wouldn't be on the top priority. You either planned the dive correctly and have enough to get out or you don't.

[kwinter]

I think most people figure that if one side fails they immediately call the dive and head for the exit, so basically get out asap and knowing pressure wouldn't be on the top priority. You either planned the dive correctly and have enough to get out or you don't.

That might be a reason to say you don't need one. But tell me what the down side is of having one? No one has ever given me a good enough reason for that. As for the fatalistic view of poor planning, you just don't know what your SAC rate could do in an emergency. Seeing that you have enough gas could be calming and reduce your consumption rate. Seeing that you might be screwed could spur you to a backup plan, like using your wing as a counterlung for semi-closed gas extension.

Knowledge is power.

[deepdiverbob]

That might be a reason to say you don't need one. But tell me what the down side is of having one? No one has ever given me a good enough reason for that. As for the fatalistic view of poor planning, you just don't know what your SAC rate could do in an emergency. Seeing that you have enough gas could be calming and reduce your consumption rate. Seeing that you might be screwed could spur you to a backup plan, like using your wing as a counterlung for semi-closed gas extension.

Knowledge is power.

I have my SPG on my left post like everyone else, and I have a transmitter on my right post. And I will compare the two 3 or 4 times in a dive, just to make sure.

[PfcAJ]

Wing as a counterlung is on your list of possibilities?

Would you do a dive without the extra spg if it broke on the surface? If you would, then why take it anyway? Its more MORE stuff to get in the way, break, or leak, and doesn't provide any additional information. In the exceeding rare case that you'd need to isolate, knowing what's in each tank isn't really beneficial, since there's nothing you can do about it.

I think resources are better spend developing good buddy skills and reasonable gas plans.