Overcoming my shame I'm posting yesterday's near miss for the community.
Short version: I was not adequately prepared for the rebreather dive conditions and through a sequence of consequences temporarily blacked out in 35 ft of water.
I called a rebreather dive yesterday due to downwellings and rip currents during a warm water wall drift dive. In a cascade of inadequate contingency planning, poor decisions and equipment failure I had a near miss.
My pride would like to gloss it over since it ended well and I was able to problem solve adequately maintaining perfect calm and minimal distress.
Two days after a storm I planned a shore dive. Fresh scrubber, 2200psi dill and 1000 psi o2. For bailout I carried an al80 of air and a bailout o2 rebreather (hardplumbed no QD) Intending to look for lion fish in the 140-150 range for a runtime of 3 hours. Diving mccr with a fixed ppo2 stand alone computer with tables back up.
Swimming from shore out to the wall (a routine dive site 10-20 minutes away depending on my ardure) I noticed eddies and unusual stirred up sediments but the current wasn't unusually strong so I continued my decent to 150ft. Upon nearing my target depth a down current strengthened and it took hard finning to find and maintain shelter on the wall.
I aborted the dive and with great effort ascended to top of the wall at 90 feet keeping close to the wall finning hard . Once the top of the wall I was unable to swim against the rip current. (At this point I flooded my backup deco rebreather by opening the dsv inadvertently.) I took shelter and decided to wait out the current (typically they don't last long) while slowly making my way inland 40 minutes later the current was not stopping. I had 30 minutes accelerated deco obligation according to the x1. On the sandy bottom I hand over hand dragged myself. By the time I was in 60ft of water 1/3 of the way to shore I was down to 400 psi of o2 from the hard swimming. By the time I reached 50ft depth I was down to 100psi o2. I began running the 21% dill semi closed to conserve o2. Getting low on dill by the time I reached 35ft depth (1/2 way to shore and dill ppo2 of.45) I stopped to rest and work to recover the loop on the flooded o2 breather. After 4 purges I attempted to switch loops and immediately took a mild caustic hit from the soaked. It was a tentative breath but still enough to start me choking/coughing a little before going back on my primary rebreather. During this process of catching my breath I added dill but did not do a flush. perhaps 2 minutes later I began to feel strange, relaxed and caught myself musing about renuilding a valve while unable to count smithers code on my hud (similar to being narced overworked down deep on air). Took all my focus to add some of the last of my o2 while fumbling for my oc bailout reg. I go off loop still feeling euphoric and perhaps hallucinating. A few dozen OC breaths, breathing regular and normal but fixated on my hud now even though I'm off loop. I begin to switch my computer to OC. Next thing I know I am standing vertical. Don't know how long I was unconscious but I was negatively buoyant and still don't know how I ended up standing from my prone position in the sand. It took 2/3 of an al80 to make it to shore where I used the remaining 1000 psi at 10 feet clipped off to an abandoned boat anchor I found to deco, considering my dive and to look at pretty things with UV light. Runtime: 186 minutes.
First off, does it sound like I am correct I experienced a delayed onset hypoxic shallow water blackout? Secondly, an al80 was wonderful to have along with me instead of a 40 but a full onboard o2 would be even better. 3rd, Install QD to plumb in all available gas, a couple lp inflator hoses stowed would have given me access to another 40cube of oxygen instead of having it trapped in my second breather and a could have run my al80 scr longer to further pad my deco. FIinally I'm glad to be living.
Off to go test dive the o2 breather, I'll check back for questions, rebukes, analysis or comments later.
Did I mention it developed into a night dive?
Cameron
Whoa, Dude! So glad you are still with us.
