First open water dives with rebreather...

[beester]

It took me about 50 dives to get fully squared away and be ready for blue water deco and short tech dives (50m, 30-40 min deco). I think I was reasonably squared away in OC (doing 2h+ deco on certain dives), but starting rebreather was still a nasty surprise.

Most of the tips have already been given (min loop, weighing, making sure on ascend to really pay attention on min loop, dive around something instead of over it if possible, adjusting small depth changes by moving instead of managing buoyancy). However for me the big "eureka" moment came when a very experienced jj diver diving the same (GUE) setup told me after a dive, you are to head heavy... or you should move your weight a bit lower or get longer tanks (moving your centre of gravity backwards). I dived his unit (with slightly longer tanks) and it was a difference of day and night.

Before whenever I would hover without moving anything, I would slightly but steadily start tipping over head first, unless I would make adjustments (stretching legs, moving my head in my neck, tucking arms in), after the change I can just hang motionless in the water just like OC.

So my tip: don't underestimate COG (centre of gravity) when weighing yourself for CCR diving. Specially if you have been so used to have fixed (diving hog doubles).

 

[nadwidny]

The thread is about first open water dives on rebreather. I aint whining about it, aint complaining it's "so hard" neither, just building some common ground with the OP and attempting to be encouraging.

******* up occasionally is a good thing, it teaches humility. You should try it sometime.

I died diving a rebreather last November. Does that count??

 

[lostsheep]

I died diving a rebreather last November. Does that count??

partial credit?

 

[Aaron Harmon]

So is that just a slightly angled trim (feet being a bit down relative to your head so a little like this / ) or just bringing your head up more in your normal trim?

If the air makes it into the bottom of the back mounted counter lungs (like if you go heads down) it can be unavailable breath until you come back to a slightly heads up position. The instinct is to add air which impacts buoyancy and really isn't needed. If you then float up, the air in the counter lungs expands further and PO2 could drop which would activate the o2 solenoid adding even more volume to an already over filled system. The important thing is to be aware of what is happening so that you can avoid it or plan for it, depending on the situation. I have a lot to learn but I progressing well and am not venting nearly as often.

Aaron

 

[Aaron Harmon]

I think the thing that helped me mentally... and I don't recall who told me this or where I read it... but it's this...

On open circuit, your first instinct is to change YOUR buoyancy every time... breath in or out... add or dump air for your wing... etc...

On closed circuit, it helps a lot if you stop to think about whether you NEED to change your buoyancy if you COULD just swim to the point where your current buoyancy is ALREADY correct and neutral. Maybe you just swim down a bit to the point where the problem goes away? Or you could overcome a temporary change in buoyancy as you go over an obstacle with a couple of extra fin kicks instead. Just a thought.

This. That is what my instructor told me and I started doing it last night. It make a big difference. On an hour long dive I vented maybe three times total.

Aaron

 

[Aaron Harmon]

Another one of those that questioned what the hell I just bought and if it was a bad mistake. I will admit my learning curve was a lot flatter than the others. Dialed in on the 3rd dive? Not a chance. A lot better on the 3rd, but not dialed in by a long shot. I racked up hours for the first year with my MOD1 and that was where I needed to be. Year two I finally got to use the rebreather like it should be after getting the Normoxic Trimix class.

I'm still not as dialed in as I was on OC. But I do enjoy the CC diving a lot more. Even with the added complexity, I find it a lot more comfortable.

I wonder how I would do on OC? I am sure my air consumption would be through the roof.

I said my "kit was dialed in, in terms of adjustment." I'm not dialed in lol, I am weighted correctly and my equipment is just adjusted and fitting me the way it should be.

On the fist day, it was too lose, riding too low and I was overweight. Once those issues were fixed, I was much more able to work on technique. It will a long time before I am "dialed in" : )

 

[Aaron Harmon]

It took me about 50 dives to get fully squared away and be ready for blue water deco and short tech dives (50m, 30-40 min deco). I think I was reasonably squared away in OC (doing 2h+ deco on certain dives), but starting rebreather was still a nasty surprise.

Most of the tips have already been given (min loop, weighing, making sure on ascend to really pay attention on min loop, dive around something instead of over it if possible, adjusting small depth changes by moving instead of managing buoyancy). However for me the big "eureka" moment came when a very experienced jj diver diving the same (GUE) setup told me after a dive, you are to head heavy... or you should move your weight a bit lower or get longer tanks (moving your centre of gravity backwards). I dived his unit (with slightly longer tanks) and it was a difference of day and night.

Before whenever I would hover without moving anything, I would slightly but steadily start tipping over head first, unless I would make adjustments (stretching legs, moving my head in my neck, tucking arms in), after the change I can just hang motionless in the water just like OC.

So my tip: don't underestimate COG (centre of gravity) when weighing yourself for CCR diving. Specially if you have been so used to have fixed (diving hog doubles).

Similar issue for me but opposite I was initially too bottom heavy. Adjusting the position of the rebreather (shoulder straps) and moving a 3 pounds out of the weight pocket and into a mid back trim pocket made all the difference in terms of my ability to stay in something approximating the appropriate trim. It comes and goes but prior to these adjustments, I wasnt even in the ball park.

Aaron

 

[_Ralph]

I died diving a rebreather last November. Does that count??

Sorry Brian... I had to chuckle a bit longer than I should have at that!

_R