this is especially for the cold water divers who dive rebreathers under current or other work loads. the more I read about breakthrough and the inability as of yet to detect breakthrough CO2, the more I wonder if strong current and cold water are appropriate applications of CCR diving.
Like a moth to the flame, i am drawn to the current swept passes here in WA and the nothern gulf islands of British Columbia because that is where healthy, vibrant inverts and fishes still remain. The added range in depth and time that CCR’s have to offer will undoubtedly tempt me to start my dives earlier before slack and push the envelope a bit after slack ends, in both cases exposing me to moderate, sometimes even strong current. I wonder if the added respiration rate from the added kicking amounts to an appreciable hazard, especially when taking into account the effect that cold water/air has on the rate of reaction in the scrubber.
I’m drawn to RB’s in part because I hate worrying about how fast my gas is being used up when I’m in a current on OC…there are plenty of times when I would just assume kick harder, stay warmer and extend the dive…if only I had more gas. Most of my dives are kayak dives/effectively shore dives and thus I must return to the entry point by the end of the dive…I drift with the ebb and flood as efficiently as possible but it doesn’t always work that way in these waters… micro currents and reverse eddies sometimes cause ebbs and floods to go in the same direction, and sometimes you see something really cool and you want to work against the current to maintain your vantage point. I’m very attracted to the idea that I will be able to kick harder, stay warmer and extend my time at the precious reefey areas with a rebreather without being so limited by my air supply. Would this be considered a heavy work load? Too heavy to be safe? Are their cold water current CCR divers out there that care to share their tolerations? Is there any one who knows how the testing of the scrubber units of the various CCR’s compares to diving against, say a ¾ knot current in 45 F water? In your oppinion does a particular unit hold up to higher respiration rates in cold water better than another?