Access to on-board O2

[Dave Sutton]

^^^^ What they said.

From 20 feet (6 meters...) even if it's all balled up and all you have is air: "We can treat bent"...


Dave

.

 

[Diving Dave]

It's a standard 102 cm stage hose...

... except it's forged from woven kryptonite! :spin:

 

[dmainou]

Plain old miflex yellow hose.

For me it works because:

most of the local wrecks are at 50m.
I carry 5l bottles as an alternative to a weight belt and larger bailout bottle.
It helps with the oc bail out plan and deco schedule
It helps to minimise the amount of off board bailout I require.

This is a popular setup amongst local divers and I know Alex and wife have 5l bottles on their jj's as well.

Smaller cylinders on deeper dives may be a different story but for the Sydney wrecks it makes sense.

D

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[divingtactics]

O2 is your least valuable bailout gas and easiest for your surface support to get to you.

If "really" 300L (1/2 3L cylinder) / 15min of Open circuit O2 is valuable you probably don't have enough other bailout of a good enough support team for your dive.

Then balance this against the additional failure points (that onboard O2 is pretty valuable for running the loop), entanglement hassel and configuration hassle. Then for me access to onboard O2 is not worth it. If I really need O2 then a 40cuft/5.5L is a better option.

A point well made, I personally have twin 7 litre steels on my JJ, even if it was 50% full it would still be more than 800 litres. I like the idea of the cheater that Rob is suggesting, just need a small second stage as pocket real estate is at a premium and I don't like the idea of tucking it away somewhere on the rig itself.

 

[Bobjr]

A point well made, I personally have twin 7 litre steels on my JJ, even if it was 50% full it would still be more than 800 litres. I like the idea of the cheater that Rob is suggesting, just need a small second stage as pocket real estate is at a premium and I don't like the idea of tucking it away somewhere on the rig itself.

Pockets are never big enough

 

[Tiptopperoo]

I quite like the idea of having a quick connect on my bailout 50% reg. That way it should be O2 clean and I've not introduced a fail point onto more regs than need be. I can always quickly switch back to my deep bailout reg while I disconnect the reg from the 50% and put it on my on board O2.

Although with 3L on boards the benefit may be negligible, for big dives with 5 or 7L onboards, that is a lot of O2 you have access too. If the dive has really gone tits up and we're on a bend and mend schedule then I'd be sitting at 6m on 100% for as long as possible. We can certainly fix bent, but not without a re-compression chamber and who knows how far away that is. An extra 5mins deco may make a lot of difference.

Dave

 

[Hanssing]

I use the optimal DS setup

When DS peaked out, the 3-hose design for the rEvo was concieved.
I consider O2 supply critical, and due to the high pressure on a mCCR I had trouble keeping wing/inflator working.

Right now, and for the last several years I have had an extended inflator-hose running over my *right* shoulder, using a green hose, and a CEJN221 fitting for the inflator. Driving the wing using O2 when I need it on the surface or I need the redundant lift while submerged.

The CEJN matches my 3-hose offboard block in my left shoulder, and I can interconnect them.

Why this setup?
I or a buddy cannot accidently breathe from a live O2-reg.
The inflator has a fairly robut design and does not leak my precious O2.
I still have O2 access, and I have redundant wingsupply.

As I said, Dave peaked out with his 3-hose setup, it just needed a little tweaking. Everything since has been inferior :trophy:

Nicolai

 

[packeteer]

i will be doing the same as Rob but use a Mares MV Octo

this is on top of my normal BO ie. 02 is only used to accelerate deco

 

[Marc_d]

Thanks for all the feedback. I think I'm going to go the straight forward route at least for now, and just add an extra hose with a flow stop and one of my old regs. I still like the idea of just having an extra O2 hose which just uses a QD to connect to the BOV though. Hmm.

Remember by that connection to bov you wouldn't be able to share the o2 if needed unlike connected to a separate second v stage. I have separate from 02 first stage on outside counter lung by o2 HP with flow stop. Easy to get. I used a AP large bore hose with the flow stop and a buddy auto air female connector with the AP male nipple. You can either of these parts with valve checks or not if you don't fancy a few early wet breaths. An apeks egress just plugs straight in with very nice flow.

I also added a l.p. hose to each stage set up so you could either use as suit inflate back up or plugs into mav if needed.

My bov is plugged directly into deep bail out so available upon bov switch over. Second stage regs also on tins for that omg the loops flooding situation.

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[alexasigno]

As Diego mentioned I'm using 5L cylinders so that's a lot of potential gas there I could make use of should something go seriously wrong. I'd also rather get on O2 as quickly as possible as breathing O2 before going to the chamber significantly increases your recovery odds.