Archive for May, 2015

I’ve been away for a few weeks, and for at least part of it I have an unusual excuse for it: I was scuba-diving in Key Largo, Florida, fine-tuning my newly-adopted side-mount scuba rig. Yeah, now I’m diving with doubles.

P927-lionfish-webMost people regard scuba-diving as a high-adventure, high-risk sport, based on impressions they get from movies like  JAWS and The Deep. There are risks, but predators are very low on the risk profile, and venomous fish (like this lionfish – a native of the South Pacific, a pest in the Caribbean) are dangerous only to the unaware. The real risks come from the fact that you’re carrying your air with you – a small closet’s worth, about 80 cubic feet (2265 litres) in the most commonly-used tanks – and the regulator feeds it to you at depth pressure: At 33 feet (1 atmosphere water pressure), each breath takes about twice as much air out of the tank as you would at the surface; at 66 feet (2 atm), three times as much; and so forth. You also use more air when you’re excited or nervous, or when you’re swimming hard … plus big guys use more air than smaller divers … and some of us just have less efficient lungs than others, and so we’ll go through a tank of air faster than the average diver.

That’s me. I’m an air hog, an airoholic. I’m the first one to run low on air, the limiting factor on the dive. I can use larger tanks at home, but very few dive-resort operators have anything on hand larger than the ubiquitous “aluminum 80.” But there’s a solution … carry more than one tank. Where? You can mount them as independent doubles (each with its own regulator) on your back … or you can clip them at your sides, below your shoulders, in a system called “side-mount.” That’s what I chose, and I was able to take a side-mount diving course in Thailand last December. (I didn’t go there for the course – no, of course not. But the diving wasn’t all that good – poor visibility – and the course was available, so I took the opportunity.)

When I got home, I went straight to work on converting my DiveRite Transpac (a harness-and-wings buoyancy compensator, or ‘BC,’ designed for both side-mount and the much-more-usual back-mount) for side-mount use. It’s different from the Hollis BC I’d used in my course, and I found that DiveRite had both the instructions and the hardware I needed to make the change. I mounted bungee-straps and rings under my armpits (a DiveRite kit), and two pairs of ‘stand-off’ D-rings on my waist belt, for attaching my tanks. My integrated weight pockets needed to go behind the “upper” D-rings, almost over my kidneys.


Stage-straps and tank hardware

I also needed a way to attach clips to the dive-operator’s tanks; my instructor used a big bolt-snap on a “lark’s-head” loop of line on the neck of his tanks, and another one tied to the same sort of ‘cam-bands’ we use to strap the tanks to our BCs, on the tail of the tank. I decided to use something like the “stage straps” tech divers use to handle their extra tanks, with a strap looped around the neck of the tank (for the top snap) and the cam-band; this way, I could almost-automatically put the top and tail clips exactly where I needed them to hook into my BC. When I had it “all together,” a dive-instructor friend let me do the ‘final’ (I thought) adjustments in the pool where he was running his basic-scuba class, and lent me a pair of ’empty’ (unfilled, low-pressure) aluminum 80 tanks to work with. It worked very nicely, and I set up a trip to the Florida Keys to get the practice I’d need to “take it on the road.”

My first dive-day in the open ocean brought out flaws in my system that I hadn’t noticed in the pool. I’m sorry to say I embarrassed myself; the cam-bands on my tanks were slipping, and I was struggling with them to get them tight, and it left me floundering. There was a strong current that day, which certainly didn’t help … and I took a one-third-empty tank as my second tank on the second dive, then lost much of it to a free-flowing regulator that I didn’t catch in time. So I came up low on air, and exhausted from a hard surface swim back to the boat. I made a dismal showing … and I lost my new-to-me SeaLife camera and the strobe I’ve been using for a couple of years, on the first dive.

The good thing? I figured out what went wrong with the tank-bands. One, I’d put them on dry, and they’d loosened while wet; the other, I had the stage-straps rigged so the cam-buckle closed on top of them, and that made the cam-bands even more prone to loosening (and one buckle, once, popped open in the water!) So I switched things around so the tank-band’s tail went away from the stage-strap, and when I tried it on a tank on the dock, it held firm and stayed in place. Problem solved. (And it stayed solved.)

The worse thing? The manager of the resort called me up to the office, that evening, to tell me I’d have to dive back-mount like everyone else … I told her that in that case I might as well go home tomorrow, because working the kinks out of my gear was the whole purpose of my trip. I brought my C-card and the course handbook with me, to show I’d been trained; I explained the cause I’d found for the trouble I’d been having with the tank-bands; and, finally, I agreed to pay for an instructor to dive with me as a ‘personal guide’ for the rest of my trips. She said she’d call the captain and get back to me later….


Side-mount ready, relaxed and competent

The best thing? The rest of my diving went smoothly. My tanks stayed perfectly in place, whether clipped high on my waist (when they were full and heavy) or low (when they were less-full and ‘floaty’). I got two fresh tanks for my second dives (and paid extra for them), rather than trying to “save air” by carrying one of my first dive’s tanks on my second dive. And I found my Zen-place, relaxed, and smoothed out, practicing the lessons of my side-mount course and joining them up with the experience I’ve had with years of “regular” diving. Best of all, I did my third day’s diving with the instructor who had wanted to throw me off the boat the first day – and he was surprised at how smooth, careful and relaxed I’d become, and perhaps a little amazed at how I followed him through a tight swim-through by unclipping the tails of my tanks, swinging them up and pushing them tails-first in front of me – even more streamlined than he was, with his back-mount gear.

Yeah, I’m a full-out convert to side-mount diving, and I’m ready to take it traveling.

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