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Plunging into the Tec Deep Diver Course January 29, 2009

Posted by Chris Sullivan in Dive Log, Technical Diving.
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The dive club’s annual Labour Day weekend in Brockville was the final stage of my technical diving course. There were 3 students on the dives – Dave, Pete and me. Dave was already a technical diver with another agency, IANTD I think, Pete was a Divemaster, and I was working on it. I still didn’t have a technical BC, but the Seaquest Raider was adequate for the dives we were doing with 50lb of lift and the ability to accommodate doubles. One thing it lacked was a double bladder (it has the capability as an option), which can be a problem if it fails, as the only weights I was using were my tanks. Needless to say, dropping your air supply on a deep decompression dive in order to become buoyant can be hazardous to your health. I had to rely on my lift bag as a backup, but I feel safer now that I have real double-bladder wings and a backplate.

In July, when in Brockville for the wreck diving course, my last dive was on the Daryaw, and this was the first dive of this trip. The Henry C. Daryaw is close to the Canadian side of the river and rests upside down in about 100 feet of water. The centre section is raised from the bottom and provides convenient shelter for doing training exercises, so we headed down the line, doing bubble checks along the way, and settled in a ring around Brad to practice our skills at a maximum depth of 98 feet.

The first skill was valve shutdowns. After not being able to reach my valves in my dry suit I was pleased to find that I could get to them in my wet suit, although with some difficulty. The doff/don of the Scuba unit exercise, while in my 3mm wet suit was  much better than my struggles in a buoyant dry suit, didn’t go that well. I was quite negatively buoyant while kneeling on the bottom, and lost my balance when I took the it off my shoulders. I eventually got it back on but I was glad noone was filming me. We also dropped and picked-up stage bottles which wasn’t a problem. The Raider has nice big D rings that are easy to locate and clip. I find my OMS IQ pack more difficult to clip to, as the bottom rings are further back.

I learned something from Dave on that dive. His doff/don procedure kept some of the weight of the BC on his right shoulder, which helps a lot with the balance. While I thought that might count as cheating, I did it the same way after that, and never lost my balance again. I also remembered to add a little air so the Scuba unit would be less negative and easier to handle.

After the skills practice we swam out of the wreck and into the strong current of the St. Lawrence River. We drifted along the bottom for a few minutes, then deployed our lift bags and ascended to our decompression stops. While Dave and Brad were using Cochran computers, Pete and I had the Apeks Quantum which is a lot more conservative. I could see the impatience building as we waited and waited for our computers to clear. My joke for the rest of the weekend was that divers with Cochran computers tolerated bubbles better than us Quantum users, because they didn’t need decompression stops and we did. I did read a review of the Quantum compared to the Cochran Commander which didn’t have the same degree of difference between the deco times as our experience showed.

After a nearly perfect dive, while we were waiting for the boat to come and pick us up I made my biggest error. I was holding the lift bag in one hand and the reel in the other when I dropped the reel. All 50 metres of line spooled out as it sank to the bottom. We retrieved it but I had a real tangled mess to deal with, and had to face the teasing of my fellow divers back on the boat.

Total dive time was 1 hour and 2 minutes. The water temperature was a balmy 22C (72F) which was just fine in my 3mm wet suit without a hood, especially as we were either protected from the current or drifting along with it for almost the entire dive.

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