dmcutter
Contributor
Don't know if this is exactly the right place to post this, but I don't think it really qualifies for the rebreather forum.
My instructor/LDS owner is a Dive Rite Optima instructor and he just ran a little discover rebreather course for me and one of the other guys that frequents the shop. Week before last we spent about 3 hrs one night going over assembly and function. Last week we spent two nights in the pool swimming with them. Yesterday I got to test drive it in the quarry. Things like this and a full face mask make me appreciate the simplicity of a regular mask and open circuit!
First of all, breathing is quite different from open circuit. The Optima has the counterlungs over the shoulders so it's supposed to split the dif between front and back mounted. Once I got used to the work of breathing and got the volume more or less dialed in, it was not any stranger than when I first started with open circuit. Much more comfortable the second night than the first. Second, buoyancy is different. I'm used to fine tuning by inhaling and exhaling and that doesn't work since the system is closed. Well, you can descend by exhaling through your nose, more on that later. In the pool in only 9 ft of water I had a hard time getting completely neutral. One little puff of air too much or too little had me bobbing, but no uncontrolled ascents, thankfully. Third, it's quiet. You can hear the auto demand valve fire and I had a little wheezing sound, I guess the valves, but absence of bubbles is really neat. I was really impressed with how neat and compact the unit was. With two 13 cf tanks and a bp/w, it weighs in at about 45 lb. In a 2 mm shorty, we had 4 lb of weight in the pockets. Weighs a bunch less than an LP112, I think.
Yesterday's quarry dive generally went well. We ran through the system checks and set the PO2 at 0.7. I also had a 40 cf bailout slung. We just swam the wall of the quarry at a relatively leisurely pace at depths from about 25 to 44 ft. It was 64 at 44 ft and I regretted not wearing gloves, but I wanted to make sure I could feel all the bits and pieces I might need to fiddle with. I was a touch underinflated so I was swimming harder than necessary, but since I didn't get to do a bike ride yesterday I wanted to make sure I got some exercise, LOL. Between the cold at times and the extra finning effort, the work of breathing was definitely more work than the OC dive I did beforehand. I noticed my mask fogging a lot more than usual. When it fogs I usually just let in some water and slosh it around then clear it, but I think the hoses and counterlungs prevented my from sloshing side to side as freely as I typically can. I suspect that my mask was fogging more because I was exhaling warmer, moister air through my nose than you usually get from bottled gas, but maybe I just needed to use defog instead of spit.
The only real gaff came at the end of the dive. There's an airplane cockpit sitting in 30 some feet of water with the top edge at around 15 ft. We went there and I was hanging at the top for my 3 minute safety stop. I noticed that it became very hard to exhale and I thought maybe I was just tired. I kept blowing out my nose to deplete the counterlungs but it didn't make any difference. By the end of 3 minutes I was actually feeling a little stressed. I motioned to my instructor I was ascending and let go of the plane. I started floating up real fast even though I was venting from my inflator. Turns out, and I would have known this had I undergone the complete training regimen, that the problem was the .7 PO2 setting. I should have either turned it down to .4 when we shallowed up, or purged the system with O2. The system kept pumping in oxygen to maintain the .7 so it was blowing up the counterlungs, hence making it hard to exhale and increasing my buoyancy.
All in all, I really liked it. My ultimate aim is to do deep wrecks and I think the increased bottom time, decreased deco obligation, and relative "simplicity" compared to back gas, travel gas, and deco gas with attendant regulators are very appealing. Of course, the cost of entry is pretty stout, so I'm not going to be rushing out to buy one any time soon, but I am appreciative for the opportunity to try one out (even if it only makes me appreciate how simple OC is).
My instructor/LDS owner is a Dive Rite Optima instructor and he just ran a little discover rebreather course for me and one of the other guys that frequents the shop. Week before last we spent about 3 hrs one night going over assembly and function. Last week we spent two nights in the pool swimming with them. Yesterday I got to test drive it in the quarry. Things like this and a full face mask make me appreciate the simplicity of a regular mask and open circuit!
First of all, breathing is quite different from open circuit. The Optima has the counterlungs over the shoulders so it's supposed to split the dif between front and back mounted. Once I got used to the work of breathing and got the volume more or less dialed in, it was not any stranger than when I first started with open circuit. Much more comfortable the second night than the first. Second, buoyancy is different. I'm used to fine tuning by inhaling and exhaling and that doesn't work since the system is closed. Well, you can descend by exhaling through your nose, more on that later. In the pool in only 9 ft of water I had a hard time getting completely neutral. One little puff of air too much or too little had me bobbing, but no uncontrolled ascents, thankfully. Third, it's quiet. You can hear the auto demand valve fire and I had a little wheezing sound, I guess the valves, but absence of bubbles is really neat. I was really impressed with how neat and compact the unit was. With two 13 cf tanks and a bp/w, it weighs in at about 45 lb. In a 2 mm shorty, we had 4 lb of weight in the pockets. Weighs a bunch less than an LP112, I think.
Yesterday's quarry dive generally went well. We ran through the system checks and set the PO2 at 0.7. I also had a 40 cf bailout slung. We just swam the wall of the quarry at a relatively leisurely pace at depths from about 25 to 44 ft. It was 64 at 44 ft and I regretted not wearing gloves, but I wanted to make sure I could feel all the bits and pieces I might need to fiddle with. I was a touch underinflated so I was swimming harder than necessary, but since I didn't get to do a bike ride yesterday I wanted to make sure I got some exercise, LOL. Between the cold at times and the extra finning effort, the work of breathing was definitely more work than the OC dive I did beforehand. I noticed my mask fogging a lot more than usual. When it fogs I usually just let in some water and slosh it around then clear it, but I think the hoses and counterlungs prevented my from sloshing side to side as freely as I typically can. I suspect that my mask was fogging more because I was exhaling warmer, moister air through my nose than you usually get from bottled gas, but maybe I just needed to use defog instead of spit.
The only real gaff came at the end of the dive. There's an airplane cockpit sitting in 30 some feet of water with the top edge at around 15 ft. We went there and I was hanging at the top for my 3 minute safety stop. I noticed that it became very hard to exhale and I thought maybe I was just tired. I kept blowing out my nose to deplete the counterlungs but it didn't make any difference. By the end of 3 minutes I was actually feeling a little stressed. I motioned to my instructor I was ascending and let go of the plane. I started floating up real fast even though I was venting from my inflator. Turns out, and I would have known this had I undergone the complete training regimen, that the problem was the .7 PO2 setting. I should have either turned it down to .4 when we shallowed up, or purged the system with O2. The system kept pumping in oxygen to maintain the .7 so it was blowing up the counterlungs, hence making it hard to exhale and increasing my buoyancy.
All in all, I really liked it. My ultimate aim is to do deep wrecks and I think the increased bottom time, decreased deco obligation, and relative "simplicity" compared to back gas, travel gas, and deco gas with attendant regulators are very appealing. Of course, the cost of entry is pretty stout, so I'm not going to be rushing out to buy one any time soon, but I am appreciative for the opportunity to try one out (even if it only makes me appreciate how simple OC is).
Last edited:
I can see the appeal, although I'm staying OC for the foreseeable future.
