Scuba with RB buddy.

[Rick Inman]

I'm doing a dive tonight with a guy newly certified on a RB, and I know almost nothing about RBs. As a scuba diver, what should I know about to be a good buddy for this guy (we have about 60 scuba dives together already). What should I be aware of? What are the different limitations? What unique skills might I need to know?

 

[MechDiver]

I'm doing a dive tonight with a guy newly certified on a RB, and I know almost nothing about RBs. As a scuba diver, what should I know about to be a good buddy for this guy (we have about 60 scuba dives together already). What should I be aware of? What are the different limitations? What unique skills might I need to know?

Wouldn't your buddy be the best person to answer this? I would also assume, being where you are, that its an SCR and not a CCR.

MD

 

[poseidan]

Make sure he monitors his PO2 all the time.

 

[caveseeker7]

As a scuba diver, what should I know about to be a good buddy for this guy
What should I be aware of? What are the different limitations? What unique skills might I need to know?

As far as a good buddy, you're off to a good start.

The limitations as well as the setup are different from one model rebreather to next.

The one thing they all have in common is that the gas in the loop is usually not the same as in the supply tank(s).
Hence poseidan's important point to stay on top of the loop contend by monitoring the gauges. Especially during descent and ascent, when ambient pressure and thus pO2 change drastically.

Make sure your buddy does his pre-dive checks and pre-breathes the unit for a couple of minutes before entering the water. That should prevent problems form occuring in the first place, and gives you a chance to get to know and understand the RB a bit.

If the unit has electronics and sends warnings (either by warning tone or lights) make sure the problem is fixed before you hit the water, and attended to if it occurs UW.

Unless you know the unit well enough to run it for him you should stay away from any buttons and such. If he needs aid because he his incapacitated go to open circuit, either the buddies supply or yours, and get him to the surface asasp.
Let him show you has his DSV (mouthpiece) works, and open/close it a couple of times.
Gas will be purged and water enter if he looses it, making him negatively bouyant. That's the one piece of his kit you need to be able to control.

When you first decent, halt around 15 fsw and visually check his rebreather for a leak.

Other than that just watch out for your buddy, and make sure he does the same for you. New divers can spend so much time with their displays they miss everything else.

Madmole has an article about buddying a rebreather diver on his website. While written specifically for the Inspiration, much of the info applies to other CCRs and RBs.

 

[ShakaZulu]

I don't know why your buddy doesn't use a normal setup when he's diving with you??? RB's are well outside the scope of REC divers.

 

[Camerone]

When you first decent, halt around 15 fsw and visually check his rebreather for a leak.

Caveseeker7 makes a good point - but more to this point is to have him show you where to look prior to the descent; a Dolphin, for instance, may vent between the hoses, depending on conditions, and it's normal. On the other hand, bubbles from the first stage, the hose fittings, or anywhere else is a bad sign. Closed Circuit units shouldn't vent on descent at all...

Make sure your buddy also does a "wiggle" or a "shimmy" manuver and then a full 360 degree pivot while you do the bubble check on him during the descent. Sometimes air gets trapped in the unit which can look like a bubble or two.

Generally, rebreather training addresses the "buddy" issues - in that he should've been told how to brief an open circuit buddy properly. Just make sure he gives you a good briefing, and you should be fine; he should tell you what to look for, where to check, and a quick run through of emergency procedures. One thing to note is that generally, rebreather divers more self-sufficient, in that on a properly equipped unit, you have more resources for failure handling than OC divers, but there is, of course, more that could fail.

My girlfriend dives open circuit with me all the time, and I will only dive on a rebreather. There's no good reason not to pair up, except for my greed for bottom time I hate the noise of the open circuit bubbles, the up-and-down buoyancy changes with breathing, and the bubbles scaring off the critters I'm photographing. I like my underwater time to be as silent and long as possible. She prefers the ease of setting up and cleaning up the gear (dip, dunk, and done) for OC gear, its simplicity, and she gets cold in the chilly Northwest waters after 45 minutes to an hour, even in her crushed neoprene drysuit. We still do just fine together as a buddy pair; I just live with the more-or-less one hour limitation she has, and she indulges my need to occasionally dive with another rebreather diver for those two hour+ adventures.

I would strongly disagree that RB usage is outside the recreational diving limits. I think that if you do dive a rebreather, you have a responsibility to dive more frequently than someone who dives open circuit, as there's just more going on and more skills necessary to survive. On the other hand, now that non-tec agencies are offering certifications, and coupled with units like the Drager Dolphin, which are limited by design to a rougly recreational depth and/or profiles (and are rather unsuitable for using for decompression purposes on your back gas), I think they're fully appropriate to advanced recreational divers. I don't do tec profiles, I don't make decompression dives, and yet I wouldn't even think about going to open circuit gear in open water for the type of diving I do. I don't even own a full set of OC gear, in fact...

 

[Rick Inman]

Wouldn't your buddy be the best person to answer this? I would also assume, being where you are, that its an SCR and not a CCR.

MD

Duh. Of course I'll ask him. But if he leaves out something, I sure won't know it. Just thought I could get some others thoughts before I hit the site tonight. And sure enough...

I don't know why your buddy doesn't use a normal setup when he's diving with you??? RB's are well outside the scope of REC divers.

He's a video nut. I invited him for the dive. Guess after spending all the $$ he wants to take it out for a spin.

 

[caveseeker7]

I don't know why your buddy doesn't use a normal setup when he's diving with you???

Diving a rebreather requires a different set of skills, few of which are shared with OC diving.
You learn the skills during training.
You become proficient by diving the rebreather.
So usually when you start out you stay on the rebreather for a year or so without switching back and forth.
After that ... who would want to go back to OC voluntarily ... ?

RB's are well outside the scope of REC divers.

I agree with Camerone. The dive profiles make the difference between rec and tec, not the gear.
Do you tell people Nitrox is out of the scope of rec divers?
That's what the RB buddy is most likely breathing.
How about a backplate/wing combo, it's technical gear, does that place it outside the scope of rec divers?

If you look at RBs, both SCRs and CCRs, you'll find units well suited for extended range diving and models that much better work for recreational profiles.

The Dräger Dolphin and Ray, as well as the OMG Azimuth and Submatix SCRs were never ment to be used past rec depth limits or for deco diving.

At DEMA later this week the SportKiss CCR will be introduced to the public, designed with sport diving in mind.
APD will bring its Evolution to the market, also a smaller version of an existing design targeting recreational users.
ISC has been offering the MiniMeg for over a year now, a smaller version of the Megalodon with reduced scrubber and depth rating.
All of those are usually configured with small 2ltr tanks and have limited scrubber duration making them less suitable for extended ranges.

The times are changing.

 

[wedivebc]

I'm doing a dive tonight with a guy newly certified on a RB, and I know almost nothing about RBs. As a scuba diver, what should I know about to be a good buddy for this guy (we have about 60 scuba dives together already). What should I be aware of? What are the different limitations? What unique skills might I need to know?

When I dive with RB always look for the route that will allow for the least up/down profile. OC divers should be aware that RBs use more diluent when the profile is a little bumpy so you should try to adhere to a more square dive profile if posssible. I just this minute came back from a RB dive with 2 OC divers. Although I could do the dive quite well with an AL80 I still prefer the dolphin for most rec type dives.

 

[Diver Mike]

From the British SCUBA Association documents. Translate meters to feet and there you have it. Dive Briefing for OC and RB mix.


Dive Briefing
When diving with an open circuit diver a SCR diver should include some rebreather specific
topics to the dive briefing.
- Hyperoxia. Hypoxia. Hypercapnia. SCR diver to inform the buddy of the possible
problems that might occur and present the rescue actions. Brief description of the
signs a buddy should look for to indicate these conditions.
- Controlled Buoyant Lift. A brief statement that this is the appropriate action for all
cases when the rebreather diver is unable to cope with the problem. It should be stated
that in the case of Hyperoxia the rescuer should wait until the casualty is in the
relaxed stage before attempting a CBL.
- Mouthpiece. Mouthpiece must be closed whenever it is not in the mouth.
- Bubble Check. The buddy should be informed of the need for a bubble check within
the first 6m.

Buddy Checks
In addition to standard open circuit buddy checks, you should include the specific items
relating to your rebreather. Of particular importance are:
- Mouthpiece operation. Your buddy must be familiar with the operation of the
mouthpiece in case he/she needs to operate it at the surface in an emergency to
preserve buoyancy from the counter lung.
- Over pressure valve operations. In the early dives, it may be necessary to adjust the
over pressure valve to vary the loop volume. Should the buddy’s help be required to
make these adjustments then he/she should be informed of the valve operations and of
the signals to be used.