left post vs right post

[Ontario Diver]

Originally posted by Jonathan
I must be missing something here? Please define "roll off". Just trying to get a handle on what you are saying.

...

Jonathan

In an overhead environment, it is possible/common to rub against the roof through non-perfect boyancy control (me - ;-0) or encoutering a restrictive passageway (everyone else ). In this situation, it is not uncommon for the valve knobs to be rubbed along the roof. This can have the effect of "Rolling" the knobs across the roof.

On a set of doubles, the action that the left hand valve post knob takes when it is rolling along the roof is the same as the action that you take when you turn off your valve. When this happens, it is refered to as "Rolling Off". The opposite takes place on your right valve post (the same as a single tank) - the action tends to open up the valve - hence "Rolling On".

Hope that this helps....

 

[Green_Manelishi]

I agree that monitoring gauges, etc. should be part of
your dive.

Perhaps I am not clearly stating the question.

Per "DIR" the PRIMARY is off the RIGHT post (as in wearing the
rig the RIGHT post is behind your RIGHT shoulder) and the
BACKUP is on your LEFT post (behind left shoulder). The rational
is the RIGHT post will never be rolled off and you KNOW the
reg works should you ever have to donate gas. You then switch
to your BACKUP on the left post (which MIGHT have rolled off
and you don't know it ... assuming you are NOT monitoring ...
but if it is you just roll it back on)

It seems to be a common statement that you should at all
times be able to reach the valves and re-open anything that
is closed so ...

The question:

If you run the PRIMARY from the LEFT post and breathe it
you will know IMMEDIATELY if it is compromised and you can
re-open it. Therefore it is working (and you know it) and you can confidently hand it off then switch to your backup (on the
right post which cannot roll off) ...

So far the *most logical reasons* AGAINST what I am "proposing"
are:

1) the backup driven from the right post would necessitate
a VERY short hose or it would be a major PITA.

2) the long hose on the left would lose some of its useful length
as it passed behind over your shoulders then down and around

 

[roakey]

Originally posted by Green_Manelishi
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?

Yes, which is why your inflator comes off your right post too.

Note that your middle two “ANDs”: (you are passing through a restriction) and (your left post rolls off) have a high correlation, so though you list them as independent variables, they aren’t. Especially if you’re task loaded because of the OOA situation and your buoyancy isn’t spot on.

And your last AND: (you can't get to it [left post knob] because you are too restricted). This is far less likely than the restriction simply being too small for your buddy to turn around and effectively signal that their gas supply had been turned off (if you ran the long hose from the left post).

That’s why I only count it as only a double failure: OOA and a roll off, because a tight restriction makes a roll off not only probable, but likely. And because it’ll be likely in a restriction, your buddy may not be able to turn around (the buddy always leads in an OOA situation). All related, not independent situations. And lastly, a second OOA situation might push your buddy over the edge and they may respond in a not-so-calm manner.

Roak

 

[roakey]

Originally posted by Ontario Diver
On a set of doubles, the action that the left hand valve post knob...

Careful of your terminology, OD. What we call the “right post” the SCUBA industry calls the “left valve” and visa-versa. So saying “left hand valve post” is precisely ambiguous (I can never resist a good oxymoron ).

Left and right posts are sides the valves are on when wearing the cylinder. Left and right valves are what side the knob is on when the valve outlet is facing you. Most simple K valves are left valves. But they correspond to right posts.

Go figure.

Roak

Ps. Please don’t shoot the messenger

 

[Green_Manelishi]

Roakey,

Me thinks you just provided *the* best argument against
my "proposal":

"If the LEFT post primary rolls off while I am donating in a restriction and my buddy cannot signal that he is f***ed ..."

Add to that EVEN if he can signal me do I really want to risk
aggravating the situation by giving him a reg that might roll
off? I think not. We will both have enough to handle.

Thanks my friend.

 

[roakey]

Originally posted by Green_Manelishi
So far the *most logical reasons* AGAINST what I am "proposing"
are:

1) the backup driven from the right post would necessitate
a VERY short hose or it would be a major PITA.

2) the long hose on the left would lose some of its useful length
as it passed behind over your shoulders then down and around

No, the most logical reason against what you're proposing is that it increases task loading in an OOA situation which already is at a level of increased task loading in exchange for a decrease in task loading when your task loading is already a minimum (normal dive).

To reach back and check that your left post hasn't rolled off after bumping the ceiling is a non-issue during a normal dive, as is making sure the gas supply as shown on your SPG is slowly going down. And it’s a non-issue to check your left post during an OOA situation as well.

What you’re proposing is streamlining those simple, no-brainer procedures (like they need it?) and increasing the complexity and task loading in an emergency situation.

It’s not worth it.

Roak

 

[Green_Manelishi]

Roakey,

We "crossed posts" (no pun intended) ... while you were
replying to my "the most logical ..." post I was replying to your
"if your buddy cannot signal .." post.

I agree that it is bad juju to hand off a reg that might roll
off and at best cause your dive buddy to hate you.

But i reserve my right to experiment and do what's best for
ME

NOW you may refer to me as a heretic stroke.

 

[roakey]

Gost durnit, that last post was a complete waste of time!

Roak

 

[Divesherpa]

There is a group of 6 of us in Fl who dive opposite the popular view. It works for us, but that's just us. We ALWAYS drop stages past major restrictions so OOA through restriction isn't a problem(except no mount).
Hose routing is easier for us as I mount my light to my backplate.
Cheers

 

[caverkevin]

I am merely presenting the question of "why not on left"

Because some people(like me) will not dive with folks that do this type of stuff. That long hose is MY regulator and mine is yours. Why put some on in a position that the reg they are breathing could be turn off and have no control or ability to turn it back on. Be the best diver you can be and use the best equipment so no one can have a problem you. Then it is you have fun and go dive.

KLJ