Mixed team (cc & oc)

[Zi55ou]

I dive oc with doubles and a deco stage usually I do my deeper dives with a friend who's on a jj. Now I've spent a good amount of time around the unit, helped put it together, gone through the checklists and had a read of the manual. Indeed if I had tue cash I'd go for the jj if I was stepping up to rebreathers. What I'm wondering is if there exists a good guide (unit specific preferably) for the complications that arise when diving in a mixed group? Thanks

 

[tbone1004]

why would it matter for unit specific?

There aren't really any issues that you have to worry about for mixed teams provided you both have means to share gas with each other, and a sufficient quantity of said gas. Typically a problem for the CCR diver who tends to not carry enough bailout.

 

[Zi55ou]

In terms of understanding the hud or buddy leds, knowing what is where on the handset and where those values should be at each particular point in the dive. How to successfully effect an emergency assent having to manage potentially five sources of bouyancy. Anything really I don't want to have to figure out if I need to get my buddy out of the water.

 

[tbone1004]

In terms of understanding the hud or buddy leds, knowing what is where on the handset and where those values should be at each particular point in the dive. How to successfully effect an emergency assent having to manage potentially five sources of bouyancy. Anything really I don't want to have to figure out if I need to get my buddy out of the water.

those are not anything specific to mixed team diving, that is just diving with someone who is on a rebreather. If you were on a CCR you'd have the exact same issues to deal with.

Those are all things taught in the CCR courses specific to that unit, but should be gone over with your buddy prior to the dive.

 

[Zi55ou]

That's very true. I suppose what I'm looking for is more info (on different rebreathers) with a focus on an non rebreather qualified technical diver. Probably stems from the wide gamut of information available on different units ranging from a glut of information aimed at owners or prospective buyers to very very little info about the unit.
thanks for taking the time to answer.

 

[DA Aquamaster]

I do a fair amount of mixed team diving. I do a really short but clear briefing on gas sharing. Essentially:

1) My bailout second stage is on a bungee around my neck - feel free to use it if you are in need of gas - just pull it and it will come out of the bungee loop.

2) DO NOT take the loop out of my mouth. If you do that without closing the loop, you'll flood it and we'll both be fighting over the bailout second stage. I'm older and meaner and I control the valve knob, so I'll win. (Well...not really since I usually have a stage along as well, but it helps make the point to not mess with the loop in a manner they *might* remember under stress).

With my more regular OC dive buddies we'll discuss at some point what to look for if I am non responsive but on the loop (and these things tend to be unit specific).

3) keep the loop securely in my mouth; then

4) check the PPO2 readings on the computer with the cable attached to it. If it's flashing red and is low, add O2 to the loop with the manual add.

5) if the PPO2 readings are high (over 1.2 or so), add some diluent using the dil paddle.

6) If I am not responsive and the loop is out of my mouth, close the loop, then insert my bailout reg and attempt to get me breathing again like you would an OC diver (but realistically that's probably a token effort as I'll probably drown anyway).

 

[rjack321]

In terms of understanding the hud or buddy leds, knowing what is where on the handset and where those values should be at each particular point in the dive. How to successfully effect an emergency assent having to manage potentially five sources of bouyancy. Anything really I don't want to have to figure out if I need to get my buddy out of the water.

1) If I have failed to keep the breathing loop capable of sustaining life (too low or too high O2) the chances that you, as a non-CCR diver will be able to address the issue are slim. If I am unconscious there is no real harm in adding additional O2. Even if I am quietly seizing due to really high ppO2, more O2 isn't really going to do anything worse and if anything will maintain life as you bring me up and the loop ppO2 drops. But even that is more than I expect a buddy to do. I tell my OC buddies to not really worry about what the HUD or handset is saying. If they want to check my shearwater that has the clearest most obvious display in the middle row. When in doubt squirt in O2 but focus on 2 and 3 below.

2) In light of #1 just stabilize me in the water column or on bottom. Keep the loop in my mouth, switch to my BOV knob. If my loop has fallen out insert any BO reg and purge just like you would an unconscious OC diver.

3) Bring me up best you can, vent my wing & suit as you would if I were on OC. Be on top of me. The loop will be positive but vent out my nose.

 

[sea_ledford]

My OC buddy briefing is pretty much the same - If I am non-responsive, this thing on the front of my BOV will switch me to OC. Now treat me as you would any OC diver. If you are out of gas, the reg is on the left sidemount tank. Good luck! I also mention that if the need to use my bailout O2 arises I have an in-line shut off they they need to open first.

On my last dive I actually had to donate my O2 for the first time ever! It was quite exciting. Not really an emergency, but my buddy was down to a couple hundred psi of O2, and still had a minute or two of deco left, plus the additional safety stop we do. I was 10 min+ out of deco, so I said, "you want my O2?" so we gave it a shot. Strong currents made it interesting, but it sure was nice to climb out with one less tank!

-Chris

 

[DA Aquamaster]

Zi550u, if you're reading closely you'll notice the differences in approaches between a CCR with a DSV and a CCR with a BOV. For example, if you turn the knob on my DSV with the loop in my mouth, you'll just close the loop and leave me without any gas supply as there is no second stage attached.

With a BOV, turning the knob closes the loop and brings the attached second stage into use. A BOV simplifies the immediate action steps for an unconscious diver with the loop still in his or her mouth and reduces the drowning risk in that scenario. Unfortunately, it's not all unicorns and rainbows as in many cases the on board diluent is limited and the BOV is only a short term solution before bailing out to offboard OC is necessary and the options there are also unit specific. If the diver doesn't come around in time to manage the switch, you're largely back to square one when the OC bubbles stop, unless the outboard bailout is plumbed into the system and you know the process involved to access it.

In general I'm in agreement that if you encounter an unconscious CCR diver, the odds of a successful rescue are low. The bulk of CCR training is about not getting to that point in the first place, so if a diver gets to that point, he or she has already either had a serious medical event (that will probably kill them in a cave or soft overhead situation anyway), or they've made a series of mistakes in pre-dive checks and/or system monitoring that are entirely their fault, so don't beat yourself up over it.

 

[tbone1004]

also of note, BOV/DSV is not a unit specific choice for most units, but one the diver gets to choose. I.e. most units come with DSV's as standard, but you can order BOV's from the MFG or third parties to put on them.