Thanks, but my dives will not go to 300+, even not 200+. Maybe I will do once 150m, but there must be a reason.Germie, many thanks for this detailed explanation! I had already tried to figure out the reason why CCR seems to become problematic at "shallower" depths than OC, and arrived at the CO2 problem. Very interesting to see it confirmed by someone who actually does challenging CCR dives!
Last month deep at the u455 wreck. Then it makes sence. A deep wreck or cave or a nice reef, then i can think lets go. But just a bounce touch and go for a record? No.
Another point for such dives: you go down as fast as possible, that is also more difficult on ccr. Then you go up as fast as possible 25-30 m per minute instead of the 10m/min. To the theoretically ' offgassing point'.
Hpns, i have had it it 130m. Another point you will almost certainly experience at 150+
In my experience, the risk of problems grows significant deeper than 130m. I have had hpns, and on another dive a co2 hit. And happely a lot of deep dives without problems. But never think too easy about 100+m. Even 80m is deep. No dive is worth the risk of dying.
At 100 m one minute more bottomtime is about 8 minutes more decotime with 15-20 minutes planned bottomtime.
At 130m one minute longer is already around 22 minutes more decotime. So such dives must be planned extremely carefully. And safetydivers needed. You cannot take your own gases anymore. Just 20 seconds late at 180m, go back, or you will not make it back to surface.
Already at 100m you can, or must think about safetydivers, cylinderdonkeys. I have done on a twin12 a wreckdive to 110m depth with a bottomtime of 17 minutes. Your bottomgas can be within the 1/3 rule. But forget it with travelgas and decogases. So a decostation absoluty needed. If you miss it?
Here 40m support makes such dives easier.
Deeper you need at 100mof maybe more support. Thismeans your safetydives also need shallower support from other safetydivers. Quite complex.
For example you bounce to 150m, andyou will be back at 100m, at 23minutes, your safetydiver must be there too. He
Can wait 1-2 minutes, but has to go back for his safety.
Supportdivers must be extremely skilled technical solodivers. Not for every diver.