Day 1 and 2 of my Dive Rite Choptima CCR class!

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Fires

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Interesting write up :) Thanks! Good luck with the rest of it, and I am looking forward to reading it :)
 

mikesz

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Day 1:

Day 1 of my Dive Rite Choptima air diluent decompression course started with a classroom session the morning of 06/28/2021. We kicked this off by reviewing all 13 ish chapters of the TDI CCR e-learning, while focusing on ECCR specific information. We then reviewed all the questions that I missed or misunderstood from the chapter quizzes and the final exam. The review involved in-depth discussions/explanations, me asking a million questions, as well as my instructor sharing real-world applications/experiences/examples. After thoroughly reviewing relevant concepts and theories, we unboxed the unit, and I was able to meet my Choptima for the first time. As you would imagine, we went through every part of the unit in detail, referenced the manual for clarity when needed, and put the unit together using a check-list.

After having lunch, we packed up our vehicles and drove to the pool for my first CCR dive. Surprisingly, I felt more comfortable than I thought I would be. I was able to get neutrally buoyant in the approximately 7-8 ft deep pool within the first 3 minutes of being submerged. I was also able to stay in proper horizontal trim pretty effortlessly. I spent a lot of time attempting to maintain neutral buoyancy without any hand or fin motions. I also swam from the deep part of the pool to the shallow (about 4-5 feet) part of the pool repeatedly, while focusing on not losing control of my buoyancy. We of course went through a lot of skills/drills over and over and over, and we surfaced when we needed to discuss anything. Because I had done a whole lot of research about RB diving prior to class, I was able to react to most of the drills/skills pretty naturally. The first time we practiced bailing out, I forgot to switch my computer from CC to BO immediately. After my instructor pointed it out the first time, I did not have to be reminded again. For class, I am using a set of manifolded BM LP50’s as dilout. I literally felt like there was nothing on my back (This was the first time I had dove them). I was pretty amazed at how easily/clearly I could make out words from talking into the loop while submerged underwater. The day ended with me breaking down the unit partially (since we were diving the next day), with the guidance of my instructor. Of course, this is not an exhaustive list of everything that we did in class.


Day 2:

The agenda for day 2 was to dive, dive, dive, discuss, discuss, discuss, drills, drills, drills. Day 2 started off with putting the unit together, doing all necessary checks with the guidance of the check list and my instructor. At this point, I should probably add that between day 1 and day 2, the only thing that was added to my setup was a canister light (DR EX 35). We then drove to the dive site and began dive 1. This is where the minimum loop volume and buoyancy changes began. I pretty much spent all 3 dives trying to figure out minimum loop volume and buoyancy. I felt like I was learning to dive for the first time. At the end of day 2, I knew beyond any doubt that this would be the dive course that would challenge me the most.

We started off dive 1 on the 20 ft platform. I spent some time trying to get a feel for minimum loop volume, buoyancy, as well as building muscle memory for the location of everything through repetition. We went through a million drills, and when I had performed satisfactorily on everything and felt comfortable, we went off the platform and swam around the outskirts of Hudson grotto while maintaining (more like attempting to for me) a depth of 30ft. I felt it was important to mention the addition of my cannister light because it made me significantly right side heavy, and surprisingly top-side heavy. This made maintain horizontal trim slightly harder, and it left me with a slightly overworked left knee as a result of me trying to fight the right-side heaviness. Buoyancy was a struggle! One moment I felt neutral and in control, the next moment I felt myself starting to become more negative. My buoyancy kept fluctuating at +/- 5 ft the entire day. There were times I felt like I had no choice but to vent air from my nose so that I did not become dangerously positive. I absolutely do not want to get in the habit of doing this and wasting gas. Regarding loop volume, sometimes I felt like there was way too much air in the loop, and other times I felt like there was too little. Despite sometimes feeling like I did not have enough air to satisfy my lungs cravings, I never freaked out. I personally felt like the ADV was not letting as much air as I thought I needed or deserved (I have a QC6 fitting on mine), or at least it did not feel/sound like it was. When I felt like I did not have enough air and the ADV was not letting in enough, I used the MAV. Jaw fatigue! I have never ever had jaw fatigue in OC. I do not think my JF is from the weight of the DSV. I think it is mostly from the current position of the Choptima, and where the loop sits as a result of that. I also found that there was a specific placement of the Choptima that hindered me from being able to easily access to my nose for clearing. It had something to do with if I pointed the inhale and exhale loop downwards or upwards at the point of attachment to the lungs. I definitely have some figuring out to do in that regard.

We did slightly different things on dive 1, 2, 3, but at this point, I cannot tell you which was done on which dive. Through out the day, we practiced flying the unit “manually” while on the platform, and while swimming around. We set the controller to the low SP, and maintained a higher SP using the O2 MAV. We practiced BO a ton of times, and each time I was reminded of how much more peaceful the silence of CC is. You read people raving about it all the damn time, but you truly do not understand how obnoxious the sound of blowing bubbles is until you dive CC. We practiced swimming/maintaining depth with the dil in-line shutoff closed, and only replenishing metabolized gas with O2 to maintain minimal loop volume. This might have been the skill/drill that challenged me the most. From my limited understanding, being able to maintain minimal/adequate loop volume simply by replacing metabolized O2 works on the premise that there is no depth/pressure change. The moment I became slightly negative and the gas volume decreased, adding the same amount of O2 I had been adding was not sufficient to achieve sufficient loop volume. In those moments of needed more volume in my lungs, I contemplated adding more O2, which I did not because it would exceed the PPO2 of 1.2 which I was instructed to maintain. Left with no other obvious choice, I found myself turning on the dil in-line shut off and adding some dil manually. At this point, I was typically about 5 ft deeper than my instructor, so I had to get back up there, which led to the expansion of the gas in the loop and wing. As you would imagine, now the gas has expanded, making me even more positive than I want/need to be, then I dump a little bit too much, then I become more negative than I need to/should be. What a vicious cycle! Lol! I am sure that if you have read this much you probably already realize that I am 1) transparently sharing my experience, and of course, 2) get as much tips, tricks, and feedback as possible. Amongst many other things that are not stated here, we got to practice a BO ascent from 40 ft, and I got to how dangerously high ones PPO2 can get if we start our descent with a really high SP. Oh, I almost forgot to mention.. fishes are significantly bolder when there are no bubbles present. Some of these guys literally got in my face, and allowed me to get my hands really close to them. I am sure that I am missing a million other things that we have gone through in the first 2 days of class, but I have touched on some noteworthy ones.

Class continues sat (day 3), sun (day 4), and Mon (day 5). My instructor says that he has been really impressed with my performance thus far, and he can tell that I have putting a lot of time and thought into CCR diving and all that it entails. I am very detail oriented, and am pretty much a perfectionist, so I am looking forward to continuing to learn and get better.

Congrats. Sounds like you’ve got it well under control and thanks for your excellent write up. This gives noobs like me something to look forward to. I’ve gone with the BMCL Optima and will be going through the training soon.
 

rddvet

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Out of curiosity, how do you use a hip mounted can light with the Choptima? I know you need a dring on both sides of your waist, so how do you attach your canister?
That's a general question, not just for the OP
 

Tracy

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Out of curiosity, how do you use a hip mounted can light with the Choptima? I know you need a dring on both sides of your waist, so how do you attach your canister?
That's a general question, not just for the OP
He is using a dive rite canister, they use a quick attach bungee loop on their cans.
 

rddvet

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He is using a dive rite canister, they use a quick attach bungee loop on their cans.

Sorry. I should have said if you don’t have one of the qr loops. I hate those loops. Wonder how you’d do it without the qr.
 

Tracy

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Sorry. I should have said if you don’t have one of the qr loops. I hate those loops. Wonder how you’d do it without the qr.
The bottom straps are adjustable in length, you could mount the D-ring behind the canister and clip over the can.
 

rddvet

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The bottom straps are adjustable in length, you could mount the D-ring behind the canister and clip over the can.

that’s what I was hoping. Wasn’t sure if they had to be towards the front or back of the waist.
 

Tracy

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that’s what I was hoping. Wasn’t sure if they had to be towards the front or back of the waist.
It doesn't seem to matter. It might be a bitch to clip around the canister depending on size, but certainly possible down where you are without gloves.
 
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Meka Nwoke

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Paul will know how to do this, no problem.

sounds good, I will talk to him about it eventually. I plan on diving it the way it came for now, and see if anything changes with time, familiarity, comfort.
 
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