Rebreather questions

[john j]

The mad mole beat me to the answer. Those UK dudes are quick! Let me elaborate further though to point out yet another advantage of a CCR. Lets say that I'm going on a dive trip where I plan to dive on several shipwrecks over a few days. Suppose that the wrecks vary in depth from 50 feet to 300 feet. Furthermore, because of unpredictable weather conditions, you're not sure which order you are going to do the dives. For example, you are an OC diver and you plan on diving the 300 foot wreck today and all your gear is ready for that dive. You spent a significant amount of time last night getting everything rigged for the 300 foot dive. You drive down to the boat dock this morning with a truck load of tanks and gear only to find out that the captain says the wave height is too large to do any of the deep wrecks so you'll have to dive the shallow wrecks today. If you had OC gear like doubles with trimix ready for a 300 ft dive you would be screwed because first of all, you wouldn't want to use your expensive trimix on very shallow dives and secondly, with low FO2 trimixes, you would be at a real decompression disadvantage and nearly hypoxic on the shallow dives. If you had a CCR, you wouldn't have to change anything to do the shallow dive. You could still use the trimix but the CCR would hold the PO2 constant regardless of depth. This is one of the biggest reasons that I use a CCR. I can go on a dive trip for several days and dive very shallow and very deep wrecks, all with one set of gear and one set of gasses without having to switch tanks or mixes around. No need to try to plan which wreck is dived which day-just do whatever you want in any order you want to and your PO2 is always optimized. Isn't that awesome? I choose my diluent according to the deepest dive of the trip and I can still do anything shallower and still have optimized PO2. You can't do that with OC.

Last year at Isle Royale, I used my CCR to dive everything from 250ft on the Kamloops to 4 ft deep at the bow of the America, all on 1 diluent gas. I was up there for a week, we did about 10 dives and I used something like 30 cubic feet of oxygen and about 20 cubic feet total of diluent gas. I brought two 40 cubic foot bailout bottles, one with air and the other with trimix which I only carried on the deep dives. Over the whole week, I changed my scrubber chemical once and rinsed out the mouthpiece hoses one time and that's all I did for gear maintenance the whole time. For my OC buddy, we had to dive the Kamloops first so he could use up his trimix and not "waste" it on a shallow dive. We also had to lug around a 200lb compressor just to keep filling his tanks. He needs a CCR.

These CCR's are really powerful tools.