My OW training in 1975-76 was done mostly using the Cressi ARO, a pure oxygen CC rebreather.
At the time maximum ppO2 was 2 bars, so I am certified for recreational use of these rebreathers down to 10m.
After finishing the course (6 months), I used the ARO for some nice shallow dives in the sea.
Being silent allows to come closer to fish.
And the constant buoyancy and perfect vertical trim allows to stay perfectly immobile in the water column for working or making photos.
But there are many drawbacks.
Swimming horizontally is difficult with a chest-mounted counterlung, the depth limitation is severe (and now it is just 6 meters), and the combination if pure oxygen and soda lyme is quite irritating for the airways.
So after less than a dozen dives in the sea, both I and my wife gave up entirely and continued diving with air tanks exclusively.
Simplicity wins in the end.
We also never considered modern rebreathers operating with mixed gas. Too complex, too risky.
Perhaps they make sense for deep diving with helium, but we did always dive safely with air down to the maximum depth allowed by our recreational certification (50m with deco).
I do not see on the market any significant evolution making a CC or SC rebreather to be appealing for normal recreational diving.
For specific tasks, where being silent is important, instead, a CC rebreather is a very useful device also at moderate depths.
At the time maximum ppO2 was 2 bars, so I am certified for recreational use of these rebreathers down to 10m.
After finishing the course (6 months), I used the ARO for some nice shallow dives in the sea.
Being silent allows to come closer to fish.
And the constant buoyancy and perfect vertical trim allows to stay perfectly immobile in the water column for working or making photos.
But there are many drawbacks.
Swimming horizontally is difficult with a chest-mounted counterlung, the depth limitation is severe (and now it is just 6 meters), and the combination if pure oxygen and soda lyme is quite irritating for the airways.
So after less than a dozen dives in the sea, both I and my wife gave up entirely and continued diving with air tanks exclusively.
Simplicity wins in the end.
We also never considered modern rebreathers operating with mixed gas. Too complex, too risky.
Perhaps they make sense for deep diving with helium, but we did always dive safely with air down to the maximum depth allowed by our recreational certification (50m with deco).
I do not see on the market any significant evolution making a CC or SC rebreather to be appealing for normal recreational diving.
For specific tasks, where being silent is important, instead, a CC rebreather is a very useful device also at moderate depths.
. There's no sense of ticking clock on ndl dives (decreasing gas pressure)- just an oxygen SPG which will last a pretty long time.
