What to expect?

[ajduplessis]

I love statements like this... I'm guessing you do not have alot of hands-on CCR experience...
I find that I have more options to remedy situations than I do on open circuit. I am enjoying finding new ways to deal with the same problems. An example is during my class, my buddy had a simulated OOA issue. When I gave him my BO bottle I then had a simulated boom requiring me to shutdown my gases. I was able to plug into my BO bottle and continue using SCR while my buddy breathed off my BO. Sure it was a drill, but that gave me confidence in the unit and the skills I was learning.

Sure there are different issues you do not have to deal with using OC, but I look at it like driving a motorcycle. You have to dive the unit, don't let it dive you.

If CCR's are so safe why do you bailout to OC???

I don't know of any OC equipment that state "This device is capable of killing you without warning" in there user manuals!!

 

[fishb0y]

Does a rebreather require your attention to dive it? Sure, but it's a machine... a rebreather doesn't stay awake at night thinking of ways to kill you. and I would say maybe more scuba gear should tell you its dangerous. Again, put some hours on one instead of repeating what others are saying on the internet.

 

[down4fun]

After many months of 2 friends of mine exhalting the wonders of CCR, it looks like I might finally be conceding and giving it a go shortly.

Now, I have only ever dived OC, both rec & tec, for over 20 years, so it should be an interesting learning curve.

I appreciate that buoyancy control will have to be re-learnt for CCR, but what other major differences can I expect?

Thanks

As you stated buoyancy is a big one at first. You are so used to being able to just inhale to rise and go over an object and that is no longer true. You will find on ccr you tend to go around things rather than up and over or under. But after a while it's second nature.

Warm, moist air to breath. I find that i do not get near as dried out on long dives on the ccr as i used to in o/c.

Loop volume is a big one in the beginning because with every change in elevation your volume of gas in the loop changes so learning to manage that takes some time. There is a sweet spot in loop volume where the gas moves freely and has just the right amount of volume to inhale and exhale comfortably. the first time you find that your like Yeah! This feels good. From then on you know what to shoot for. You will learn to manage the volume. For instance as you ascend the loop volume increases as the gas expands, but your PO2 is also falling so you will learn to vent as you ascend to allow for more O2 to be added and still keep a good loop volume.

It takes more prep time than o/c. Use a checklist. I've have about 200 hours on my rEvo and I still use a checklist. Don't get complacent. And have fun!

 

[Mr.X]

I test dove the Poseidon this summer (under supervision of the Poseidon team), and to dump gas from the loop, you just gently squeeze the counterlung, and the popoff valve lets it go (if it didn't already dump the excess). To add, simply inhale deep or sharply, and the diluent valve (actually a 2nd stage - also used for bailout) adds gas. No real magic here, and as a guy who never dove CCR before, the only real quirk I found was buoyancy control.

I can't say I have tried anything else, but I have to say, from what I saw, I like the Discovery, and if I go CCR, it will very close to (if not at) the top of my list. The sophistication of the unit, coupled with Poseidon's long reputation of not building or selling junk goes a log was with this diver!

- Tim

Sounds interesting. Seems like there are similar features to the original CIS LUNAR. Makes sense if Stone was the designer.

If I had favorites for ease of breathing I would say it's the Inspiration, or the MEG with neoprene lungs. Those lungs are a thing of beauty - but fragile. In tryout stages it just a matter of bumbling around in the pool with the units to get some sort of feel for breathing differently under water. Position of the lungs and distance from the centroid makes something of a difference when you are using various units. By this I mean - back mounted vs. chest mounted etc. For many OTS lungs are the most comfortable, but personally I like getting the lungs away from an already cluttered chest area.

X

 

[DCBC]

If CCR's are so safe why do you bailout to OC???

Quite right, it involves proactive use and has a higher element of risk. The maintenance is a pain, but is required (I also have paid particular attention to my parachute when skydiving, but I'm funny about things like that).

BTW much of my CCR experience has been using it as a bailout system for surface (closed bell) supply when saturation diving. They are relatively safe if used properly, but often are unforgiving to an unaware or lazy pilot.

 

[red_barbarian]

When breathing very hard on the Meg I found WOB was an issue compared to flat out swimming on OC. I don't get dry mouth or cold when diving my Meg. I used to get very cold after 90 minutes with the same exposure setup on OC. The first setup of the day requires more hands on time than OC, although the more complicated the dive the closer the two get in prep work. I can walk with my complete rig for almost all of my dives without my joints screaming in pain. With 15L steel doubles, and 2 11L Al stage tanks, I can't even stand up.

 

[Mr.X]

WOB on CCR vs OC can be very different animals. In the case of a RB you are relying on your own lungs to move gas past scrubber material, plenums, check valves, corrugated hoses etc. Additionally, body position/lung position plays a key factor in resistance. The closer the lungs are to the centroid the easier it is to breathe. Additionally, a RB user has to adopt a philosophy of steady / consistent breathing with a RB. In short - don't get to the point where you are panting. There are enough cases of where accelerated breathing have had dire consequences.

All in all - I have caveats about recommending CCR to divers who are not utilizing them for specific purposes. If someone is just interesting in bimboling around with these things OC is the way to go. Less hassle, and ultimately less concern for things going funny. Which they always do on a CCR.

X