left post vs right post

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Green_Manelishi

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inquiry:

why not drive primary off of LEFT post and backup off of RIGHT?

Advantages:

1) immediately aware primary has shut down. switch to backup
and re-open
2) if you have to hand off your primary there is no chance of
you placing a rolled-off backup in your mouth

Disadvantages?

One final question: does anyone know anyone that does this?

Ps. if you feel that I must be flamed .. be clever ,.,, don't simply
scream "you heretic stroke"
 
I'm not quite sure that I follow your pros and cons but I tend to dive primary on left, backup on right - mainly because I find the routing of the long hose easier and to keep things more out of the way.

It is one of the more bizarre sections of the DIRF book that and I really do not buy their arguament.

As long as you are aware which is where, surely that is the important thing.

Jonathan
 
Your primary concern when handing off your primary in an OOA emergency is not whether your back up has rolled off, it is assuring that your buddy has one that works.

He will be possibly a little freaked out and you should be calm enough to fix it if your back up has rolled off.

And if you use the long hose(primary) on the right post it can only be rolled off in the on position, thus insuring that your buddy is getting a good working regulator. That is asumming you are breathing the long hose and not stuffing it.

As far as routing to the left post with the long hose, I don't see how it would be better for routing since there is more distance to cover and off the right post it drops straight down between the tanks and wing and up under the cannister light and wrapped around your neck, pretty simple and easy to route.

Just my opinion.
 
It revolves around an OOA scenario.

By routing the long hose off the right post, it will NEVER roll off, so the OOA diver has one less thing to worry about. You on the other hand are breathing off a post that can roll off, but if it starts breathing hard you have immediate feedback AND the ability to turn it back on.

This is probably one of the few places where a double failure is actively considered. If you’re donating and your exit involves a tight passage, there’s a real possibility of a roll-off in a place where your buddy may not be able to turn around and communicate that their air has been turned off.

A during-the-dive roll off of the left post should be discovered on one of your SPG checks.

Roak

Ps. You're a heretic stroke :)
 
I must be missing something here? Please define "roll off". Just trying to get a handle on what you are saying.

The reason for putting the long hose on the left post for me is that I am using the port on the bottom of a Scubapro Mk20. This way I can turn the primary at an angle and I can get to the tank knob easier with no hoses in the way.

Jonathan
 
If (you hand off the right-post-driven primary)
and (you are passing through a restriction
and (your left post rolls off)
and (you can't get to it because you are too restricted) THEN
you drown
your buddy drowns
End if

or is that a time to breathe FROM (not re-breathe) your wing
inflator?

G_M
 
My buddy and I did a dive a couple of weeks ago that we knew would involve a major restriction or two. Before the dive, since I had not dived with this guy very much, I mentioned checking for a roll off after we negotiated the restriction. After the dive, he mentioned that he was somewhat suprised to find that we both had a major roll off after the restrictions. Like, a total roll off. Of course, it was easy to turn our valves back on.

So, as dumb as it is to say it, if you think you might be in roll off conditions, check before you have an out of air emergency. If you get in an out of air emergency and hand off your primary, and find that your secondary is rolled off, you have already made two mistakes. First, not checking for a roll off after "bumping" your valve, and second, not noticing that your SPG isn't changing as your dive progresses.
 
FWIW .. I am currently running the primary off of the RIGHT
post.

I agree that you should periodically and methodically "check your
instruments".

I am merely presenting the question of "why not on left" to
promote discussion.

Has anyone ever been in such a tight restriction they could
NOT access the left post?
 
I agree with Campana, if you think you made contact with something that would cause a roll-off then check your valves. They aren't going to roll off on their own. Also you aren't going to get a roll-off on your right post unless you are swimming backwards. And even if you don't check your valves for a roll off, you would know if you have accidently rolled off your left valve because your SPG would either be at zero or not move at all. I check my gauges enough to know when I'm using air or not.

Green-M you wrote that in an OOA situation that if you put your primary on your left post then you don't ever have to worry about putting a rolled off reg in your mouth. Well are you saying that it is better to give someone that is already OOA a reg that is rolled off? They are already probably pretty freaked, and when they stick that reg in their mouth they are wanting some air in the worst way. Don't you think that your stress level would be a little lower than theirs were you couls reach back and make sure that your backup is fully open?
 
I was taught the same thing. Keep your alternate on the left post so that it will get "rolled on" rather than "rolled off" . That way you know that it "should" work if you switch to it. If your primary gets rolled off - you'll figure it out pretty quickly and can fix that (giving a reason for those 398 shutdown drills that the instructor made us do!) and you can still breath off of your alternate.

I like the tip to keep checking it tho' - thanks
 
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