Here's my two yen on Independent Doubles...


1 - Why worry about your buddy?  When doing deco dives there are so many 
reasons to NOT count on a 'buddy' that this should not even be part of 
the contingency plan.  Any deep and/or deco diving is easily planned with 
a buddy, what to do in the event of an emergency, abort procedures, etc.  
But to actually make plans for gas for your buddy... well... I question 
the realism of this contingency.

2 - If you need to rely upon your buddy for gas management, then you 
(don't take this personally, I mean 'you' in the figurative sense) have 
no business in this technical situation.  The same holds true for the 
buddy.  With twin independents (or more) it is easy to plan for multiple 
contingencies.

     1 - If your first system should fail, abort immediately.  Proceed to 
the first deco stop and attempt to carry out the PLANNED deco as if the 
entire dive was accomplished.
     2 - If you should be so lucky as to have a DOUBLE catastrophic gas 
loss.  Well... there's a really good chance that Murphy has been riding 
your back, or piss poor planning/maintenance has taken it's toll, and now 
Darwin is knocking at your door.  But, theoretically this second 
catastrophe wouldn't happen immediately, therefore giving you ample time 
to proceed to your first stop.  The smart plan would have had additional 
bottles tied off at predetermined (aka First Stop) depths to bring up 
through the entire deco profile.

Any of the dives I have performed that have been 'outside the 
recreational limits' have been conducted with the pretense that all 
divers involved understand they are responsible for themselves.  We all 
have predetermined 'missions' on said dives, but we act 
semi-independantly.

The buddy should be counted on for much less catastrophic and rare 
occurrences.  Such as, entanglement (again odd, with experience), cramps 
(conditioning will reduce this contingency), equipment difficulties 
(camera, light placement, positioning, etc.).  But not a buddy in the 
sense of an "Openwater" diver.

My independent system was as follows:

Left Tank:  Reg marked with white tape (two 3/8" strips), SPG marked with 
same.  Reg hose routed over left shoulder, SPG routed under left arm and 
clipped.
Right Tank:  Unmarked.  Reg hose routed over right shoulder, SPG routed 
under right arm and clipped.

Procedures for use:

Tanks filled to 3,000 psi of appropriate gas(es)

Breath Right Tank to 2,000 psi
Switch to left tank, breath to 1,500 psi
Switch to Right tank, breath to 1,000 psi -- At this point dive should be 
well into Deco Profile, or ascent to ample gases.

This left a minimum of 1,000 psi of backup gases, which should be more 
than ample to reach the First stage in Deco, where a bottle was tied.

Points to ponder.  Ensure your reg's are secure to the point that they do 
not easily fall away from you, requiring you to fish around looking for 
your gear.
Dive this system a few times in shallow waters, get used to it.  It's 
quite simple.

If you want to add a long hose on your system(s) for your buddy, then 
great!  Let's face it, the odds in triple catastrophic gas losses are not 
only rare but on the side of incomprehensible with proper equipment 
maintenance and planning.

Good luck!  

Disclaimer -- I accept no responsibility if you should attempt to use 
this system and get yourself killed, especially if you do not have the 
proper training.  But, in my opinion this is a simple setup.  Worked 
great for me for the past couple hundred 'deep' dives.  As well as the 
eight of us that used it regularly.

Enjoy!

Rob
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