I started diving rebreathers some time ago. I got caught up in a very well marketed rebreather from overseas that was taking the US by storm. And a lot of you probably remember that I would come here and post how it was the greatest rebreather ever, having never dove any other rebreather in my life. And then a good friend of mine, Jon Bernot, challenged me (actually dared me) to try the Dive Rite Optima. I sold my rebreather the next day and with the help of Jon and Cave Country Dive Shop, we got me into my first fully electronic rebreather. I was in love with the Optima (So much so that it became the first unit I started teaching on), but I was terrified that I might be getting fooled again. So, I got certified on everything I could get close to. Today, I’m certified on rEVo, Optima, Sidekick, JJ, & Liberty. I have a Sidewinder showing up from FedEx tomorrow. But, I want to talk about the newest rebreather that I have dove, and probably my favorite rebreather of all time. This is my review of the Dive Rite Optima CM at just under 30 hours on the job.
Lamar from Dive Rite called to let me know that my Optima CM was ready for pickup just 5 days before my trip to Bonaire was to depart. I didn’t have much time for a test run, but I had to get the unit in the water somewhere before I carried it into the south Caribbean. Eagle’s Nest is the closest cave dive to my house, so it would have to do. For those of you that don’t know, the Optima CM is Dive Rites latest iteration of the electronically controlled rebreather that has been on the market for more than a decade. It boasts a scrubber at just under 6lbs. It employs the use of Shearwater Electronics and 4 oxygen sensors. It utilizes user replaceable disposable batteries and it’s one of the only rebreathers that can take advantage of both packable sorb and Extend Air Cartridges. But what really makes this rebreather stand out if that it mounts fully on your chest. Oh, and fully configured with sorb and filled oxygen bottle, weighs a whopping 31lbs. Yes, that’s less than a full aluminum 80.
Now, I have to be honest. When I first heard about a rebreather that mounts completely on your chest, I thought to myself, “What’s the point”? “Certainly, there are better ways to go.” And “this bottle at the bottom is going to get in the way of my legs and my gut.” I think I was wrong about all those thoughts. I would soon learn just how awesome of a concept this thing was.
I began by rigging a first-generation Dive Rite Nomad LT. I moved the D-Rings all the way to the tops of the shoulders where the Optima CM would clip in via two bolt snaps. The bottom of the Optima would clip to my waist D-Rings. Clipping in the unit was effortless. And the weight of this entire rig is less than half what the traditional Optima weighs. It was quickly apparent that I could simply unclip the bolt snaps at the bottom of the unit to “Superman” the rebreather to pass short restrictions. And the unit breathes perfectly fine. In fact the Optima CM breathes better than any rebreather I’ve ever owned or dived. Keep in mind, I still dive/own an Optima OTSCL, Optima BMCL, and Liberty OTSCL. I haven’t dove a Sidewinder yet, so I can’t speak to it (yet)
But I’m getting sidetracked. So, I geared up at Eagle’s Nest with some appropriate gases and a scooter for a dive somewhere above 300’. I didn’t have a lot of time and this is just a shake out dive. DIL is ran via offboard bailout bottle. Oxygen is mounted at the bottom of the unit. The “CM” has a manual addition button that doubles as an ADV on the left side and a manual add for Oxygen on the right side. These buttons are extremely well placed and easy to get to. The ADV works well. It’s not as fast or accurate as the ADV on the front mounted counterlungs of the Optima, but I haven’t found anything that is as good as the old Optima. But still, it works really well. After playing in some shallow water, I scootered straight down to the debris cone and the ADV mostly kept up with gas volume.
What amazed me was how the unit just seemed to disappear. There was no pull of gravity, no shifting of weight as you rolled left or right, and no matter what orientation, I could not get it to breathe even remotely hard. And honestly, if you think about it, having two giant counterlungs positioned right below your actual lungs has to be the best configuration out there. And this thing sure was.
TEST SUCCESSFUL!
I dried the unit and packed it for travel. We would be taking this, along with some new scooters to Bonaire. And the lightweight cargo made for awesome travel.
We started out at Buddy Dive in Bonaire for our gases, sorb, etc. They were super accommodating. We got fills, ran through our checks and jumped in the water. I didn’t get 100’ from the ladder when I realized something was wrong. I couldn’t breathe. Apparently, TSA had tried to remove the counterlungs for inspection. The inspectors unzipped the cover and tried to get the bags out and in doing so, really bunched and twisted them up. You couldn’t tell on the surface, but even in 10’ of water, there was almost no lung volume to be had. It was a simple and easy fix, but I learned to be extra cautious after someone else may have messed with my unit. (Haha, I said “unit”)
All in all, the unit worked perfectly. We did every kind of dive you could think of. Shallow stuff in calm water, deep stuff in wicked current. Really deep stuff on scooters. And even down at 483’, the unit still breathed effortlessly. It was awesome having a unit that could easily be carried by one hand. Lifting out of the water, tossing it into the truck, carrying it upstairs to our 2nd floor apartment, and taking up very little weight for air travel, it was and is the unit I will use for most of my diving. I remember telling a pretty popular cave instructor two weeks ago (before I got my unit) that it was a nice concept but not a unit for everyday diving. I’ll eat those words. Because of the way this thing breathes, how easy it is to don and doff, how lightweight it is in and out of the water, it is my new “go to” rebreather. Oh, and I believe it’s the lowest cost ECCR you can buy.
