Day 4: I'm Feeling Kind of Neutral!
A crossover requires only 200 minutes of bottom time and we were well over half of that. We had already got depth in and I clearly demonstrated to Tom that deep doesn't bother me at all. I even maintained my buoyancy with a leaky ADV. In addition, the seas were crappy and we didn't feel like driving sixteen hours (both ways) to dive up in the sinks. We decided to go a bit shallow instead and really test my trim and buoyancy in Jule's Undersea Park and Lodge in Key Largo. It's not that big of a place, so what were we going to look at for almost another 2 hours??? In retrospect, I'm not sure why I was worried about it. Tom was going to use our time wisely.
We got there and checked in with the front desk. I took Tom on a tour around the place and we looked at the map of the underwater park so he could understand where we were diving. I have taught a number of OW and Trim, Buoyancy and Propulsion classes here, so I know it well. There's silt all over the place, so this should be fun! After the tour, we went to the van and started our final assemblies. I've already got the scrubber packed and in a watertight travel bag, so I pull off the head, do a stereo check on my breathing hoses, install the scrubber, replace the head and attach the hoses. We walked our gear down to the benches near the water and I went through my check list while sitting in the shade. Turn on the PDCs, check O2... and so on. I don't have a clock on me, and I refuse to be rushed, but I don't think it took me more than five/ten minutes to do the entire check list. It's important to consecrate this time and not let anyone interrupt or disrupt the process. I was going to recite all the steps here as they aren't hard to memorize, even without trying. But then, that defeats the purpose of following a written check list. You will live or die by whether you follow the check list, or not. I choose to live. We do our five minute pre-dive breathe in silence. Neither of us passes out or feels funny, so we walk down the steps to the platform in three foot of water. It's warmer than Blue Grotto, so I'm wearing my traditional tie die shirt and swim suit. With fins and mask on, we give each other the OK sign and splash.
The first thing I notice is that I'm not trying to figure out how to breathe like at the beginning of my first dive. My posture assumes the perfect position to minimize work of breathing and I feel in control. There's a swim through arch just off the dock at about fifteen feet. It's easy enough for me to navigate on OC and I am able to handle it nicely on CC as well. Unlike OC, I'm not having to worry about how I breathe. I feel relaxed and check my PPO2 . I swim a bit to our left and come up to the cannons. Tom and I make sure that our O2 cells can register over the max 1.2 that I have set for my PPO2 by doing an O2 flush above 20 ft. I close my eyes for a second and listen intently for any possible leaks. It's eerily silent except for the clicking of the shrimp. I take Tom on an underwater tour of our home for the next two hours. I love hearing the gentle clicking right behind my head that means the solenoid is firing and I check my PPO2 often and my SPGs every now and then. I make sure that I take the route I use to stress out my student's buoyancy. Just a bit of thought and I'm negotiating these ups and downs fairly easily. They have installed an underwater barrier in this lagoon to keep students from straying into the working marina. We follow it from one end to the other. As we came to the beginning of the dock, there is a huge school of mixed yellow tails in the tear. It was awesome! As I hovered in awe, I took my mind off of buoyancy and immediately started to ascend. ARRRRGH! No, I didn't hit the surface, but rather do a bit of a spin and figure out why I'm suddenly floaty. ARRRRRGH! In a few seconds, I'm back under control. Shallow is the hardest place to maintain being neutral. With very little air in my BC, I know that it's my loop I have to deal with. Almost all the drills were done at about 50 feet on the last dive and while I had to deal with a leaky ADV, it was fairly easy to keep it at depth. Here, I'm not so certain.
So we spent more than an hour exploring. We passed the science module and the living quarters at least three times. I was able to sneak up on a Hog fish and pinch it's tail. That was fun. Jenga isn't really an option when rocks are living so Tom started hitting me with drills. I really do enjoy this part of training. Everything was going well until we hit diving the unit as an SCR. I rose nearly three/four feet during the drill. Tom gave me the emphatic sign that he wanted me to stay put. I tried it again, and came up only two feet. Tom signaled me to do it over and made that "stay here" sign with even more 'tude. I finally got the hang of it and then did it another few times to be sure. It's all about timing and maintaining your loop volume. Someone asked me earlier about how to keep rebreathers neutral, and understanding how your breathing loop changes is a big part of. Part of the process of breathing off of the unit as an SCR is going to your external gas supply. Clip in the tank, turn off the Dill and no more probs, right? Tom points to my DIL MAV and gives me the universal signal that it's screwed. Nonchalantly, I slide the isolator to "off" and hit the MAV to make my point. Hissssssssssssssssssssssssss. WHAT!?!? The isolator must have already been off, so I slide it the other way and hit it. Hisssssssssssssssssssssssssss. After a few more attempts, I finally detach the external DIL supply and the MAV no longer works. Wow. Tom applauds me underwater. I just learned a huge lesson about what the Isolator isolates and that's what training is all about!
As Kermit the Frog once opined, Time is fun when you're having flies. I was surprised to see the second hour fly by so quickly. Tom congratulated me for finishing my training on the SF2. I simply can't thank him enough. This was the most thorough rebreather class I have ever done and to think it was only a crossover. I feel very comfortable on the unit and can't wait to dive it a lot more. I'm certain I'll get better with time. Unfortunately, I have a private OW class in the morning and I won't get to dive it until next weekend. Oh wait... it "is" next weekend! I'll post on that later.
On reflection, about the only thing I don't like about the SF2 is the wing. No, I didn't use the bungees that came with it and that might have made some difference. But really, It's hard to work through the mostly closed back of the wing. Yesterday, I replaced the wing with Dive Rite's CCR XT Dual Bladder wing. It really makes working on the plumbing far, far easier. I removed the stud out of the bottom and attached the back plate & wing with two M8-1.25x20 flanged bolts. No more wobble! I will be changing the top bolt to 30mm long so I can use a washer under it. It should arrive at the house before I get back!
I also added Dive Rite's Tech Butt Plate. I've got a big butt and this will put the rails out where they should be. I picked up another one for my Nomad LTZ. I'm also going to be adding isolators to my bail out bottles. That way I can keep them charged and not worry about them free flowing. I got the Highlands isolators that show red when off and green when on.
