I can do my best to expand on what i was taught and some apparent issues but you have to bear in mind I am a total cave novice and if you want proper information talk to Matt.


At first diluent was run on thirds. So:

200 bar divide by three = 60 because we round down to easy numbers and ere on the side of safety.

So 200 - 60bar = 140bar turn pressure

However were diving very shallow water, cave profiles and we are not good with buoyancy in the shallows so we are using a fair chunk of diluent.

So to increase our range we planned on half + 20bar

So now my turn pressure is 100+ 20 = 120 bar


We are using off board bailout connected to BOVs so assuming the dive is turned due to low diluent levels we have the option of simply adding diluent via the BOV. Turn knob suck in OC gas turn knob blow into counter lungs. Pretty easy

However total loss of inboard diluent will mean total loss of wing inflation gas. Not much of a problem open water but in a cave it could be. So the choice now is to run the buoyancy off the dry suit (not my first choice) or to disconnect the dry suit and swap the feed to the wing inflate.

Frankly in the UK i run suit inflation of a separate bottle and have a spare inflate hose on the bailout anyway.


With 02 we ran thirds all the time which is both sensible and easy to do. With the average metabolic rate of 1-1.2 a 3ltr will last eight hours +. So only on caves with loads of ups and downs are we going to need to worry about 02. that said a leek can spoil any dive so Id personally have a means of injecting 02 from a redundant supply.

When open water diving on the Inspo I had my 50% deco mix with a hose on it I could plumb into the counter lung. On my KISS I use a 0.75ltr bottle plumbed into my kiss for manual injection but switched off till I needed it.


Bailout gas is planned on 100% needed to exit the cave so no thirds. Safety margins were in place via increased SAC calculations and slow and easy progression into the cave.

If you nicking bailout to supplement dill your already heading out so it doesn't rely matter unless its a monster leek and its ongoing. In which case perhaps semi closed is a better option.

ATB


Mark