Dive conditions at Avalon, 4/10/05 + OOA drills

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Posted by Dick Analog on April 11, 2005 at 20:42:29:

Conditions at Avalon dive park this past Sunday were sub-par for Catalina, but considering the gale-force winds that had been blowing just hours before, we were lucky to have gone diving at all. During our first dive, visibility was marginal by local standards: about 10-15ft, at all depths to 70ft. Lots and lots of suspended particles. Which shouldn’t be surprising: we spoke with an instructor who was teaching a Divemaster course the day before (Saturday) – she said that though the tide was at the bottom of the stairway during their last dive of the day, the surf was crashing to the top of the stairs. She was literally beaten and bruised from their entries and exits. Good experience for a future Divemaster, I suppose.

Around mid-day, the current went from zero to strong, in just an hour or so. The current coming in from the west was so intense, all the kelp was flattened to within 10ft of the bottom. There were actually flow riffles visible on the surface, similar to what you’d see on a river. We jumped in anyway, ratcheted our way to the northwest corner of the park, then enjoyed a free ride back to the entry/exit area. Groups of students who got into the water found themselves halfway through the park before the class had even collected itself together. The visibility did improve to 20ft or so after the current picked up.

The water temperature was surprisingly low, presumably an after-effect of the previous days’ storm. On recent dives on both sides of Catalina we had seen water temperatures approaching 60 degrees, but it was 57 degrees at all depths (to 70ft) on Sunday.

Memorable critter sightings included a monstrous sheep crab, which appeared perfectly capable of snipping a regulator hose in half with one of its massive claws, and the trademark 10-15lb sheephead which cruise the park and don’t hesitate to put their face in your face. During our third and final dive, later in the afternoon when most divers had left for the day, we began our safety stop clinging onto a bunch of kelp and noticed that we were surrounded by a vast cloud of small- to medium-size bass, and a somewhat smaller constellation of garibaldi. Maybe they thought we were their last chance for a handout, after everyone else had left the pool. We couldn’t do much for them. In fact, we were quite hungry ourselves and those bass were starting to look tasty. Which reminds me – we law an exciting instance of predation: a bass in the 10-12lb range came out of nowhere, stuck its nose into an algae carpet, and came away with some sort of finned thing which took several gulps to consume. Yikes! It’s tough being at the lower end of the food chain.

We went Catalina on Sunday with a specific purpose in mind: to practice some basic diver skills, and to test a pony bottle-based alternate air supply system that we had put together. We did regulator recovery exercises, mask removal and replacement, and per our commitment to Ross-O, did shared-air ascents (from the pony-bottle system) from the end of each of our first two safety stops, to the surface. On the final dive we each ascended from 25ft depth to 15ft, did a 3 minute safety stop, then continued to the surface on the alternate air system. Everything worked well. In a non-panic situation, we each drew our 13cu.ft. pony bottles down by about 500psi during the ascent from 25ft to 15ft, 3min safety stop, and final ascent to the surface. I found it reassuring to have a real SPG attached to the pony bottle (not the button-type which screws directly into the first stage reg), which I could monitor during all of our tests.

I’d like to thank AADIVER for his valuable input (off the BBS) as I put together an independent, redundant, alternate air system. We had a few exchanges via e-mail and he sent some photos of his own redundant, alternate air system. Because I don’t have a backplate-based system to hold a tank and pony bottle, like AADIVER has, anything I did had to be hung from the main tank band. There is no way I could hang a 30cu.ft bottle (like AADIVER’s) from a single bank band, so my set-up is sort of like a mini-AADIVER system. There are a couple of photos posted below which show how our alternate air system is put together.

We had a feeling we were being followed.. (These are all non-flash photos, so it’s not backscatter you see - just a high concentration of suspended particles)

Then, surrounded..

And finally, confronted.

Independent, redundant, alternate air supply which we tested last weekend.

The pony bottle has its own readable SPG, which is seen tucked under the retainer strap for the main BC hose.

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