Re: Wings and back plates

[rockport@xxxxxxxxxxxxx (John Grogan)]

On Jan 07, 1998 01:16:21, 'Greg Roach <greg@xxxxxxxxxxxxx>' wrote: 
 
 
>On Tue, 6 Jan 1998, John Grogan wrote: 
> 
>: The big problem with the second bladder is that it is in the same space
as 
>: the first.  This  means that you cannot fully inflate both together - in

>: other words you can inflate both to half capacity only as the volume 
>: available is constant.  This shows that extra lift is a misnomer.  Your 
>: 100lb wing will still only give 50lb's lift.  
> 
>You only use the second bladder if first bladder/inflator fails.  Either 
>will provide the 100lbs (and what's wrong with kilos?) 
 
My example was to demonstrate the misnomer created by some manufacturers
that you double the available lift by adding a second bladder.  There's
nothing wrong with kilos but a lot of manufacturers quote lift in lb's. 
 
>: The other problem with a second bladder is that it's another hose with 
>: another LP port used on your reg - hence more failure points. 
> 
>You don't need a second LP hose on your regs.  You can either inflate it 
>orally (even blowing against the bungees), or you can disconnect the 
>LP hose from bladder #1 and connect it to bladder #2. 
 
Oral inflation is not ideal - it involves removing and replacing your
primary reg many times.  It is less efficient and it adds stress to a
stressful situation.  Disconnecting the hose is not a good idea -
particularly as most dual bladder wings have one hose on each side. 
Therefore the LP hose probably will not reach the second inflator hose. 
Again, this comes back to creating one problem in order to solve another. 
 
You do not need a second bladder.  If you want redundancy, why not carry 3
bladders?  Why settle on 2?  Between your wing and suit, you have two
sources.  The offered 'solution' of oral inlfation or switching lp hoses
does not solve anything - it is merely a justification of having two
bladders without seeing the real problem.  Oral inflation or switching
hoses (particularly at depth) adds stress to the situation.  Why add
unnecessary stress?  Also given that divers seem to use air deep, there is
the additional stress of narcosis. 
 
Switching from using a wing (which may have been punctured) to using a suit
is far easier and less stressful than oral inflation of hose swapping. 
 
>: You must 
>: also consider where to stash the hose, is it accesable etc.  In other 
>: words, it creates more problems than it aims to solve.  
> 
>The inflator hose to the spare bladder comes out of the back of the 
>wing, behind my right shoulder, and tucks under a bungee at armpit 
>height, and also under the bottom bungee.  There it stays, tucked 
>between the wing and the tank, out of the way.  Removing it from the 
>bottom bungee frees it up for use.  Disconnecting and transferring the 
>LP hose takes seconds.  Easy. 
 
And in less time, you could have compensated by using your suit.  How long
does it take you to realise that there is a problem, release your secondary
hose and transfer the lp hose to it?  I'll bet that it takes a lot longer
than it takes me to press the inflator on my drysuit! 
 
John.