Rebreather questions

[DiverMole]

I have 4 cells for the following reason

1 is part of the VR3 and hence is a completely separate unit from the main Inspiration. Thus is is an independant third party monitor

The Main Inspiration has 3 cells for the following reason, it is possible for 2 cells to fail at the same time and hence be in agreement with each other, the 3rd cell allows you to see the dissagreement and take steps to determine which cells are correct

Multiple redundancy is very common in life support and other mission critical operations, your car has 3 breaking circuits (2 on the main brakes and a handbrake)

Yes, cells are a disposable item and are not as reliable as a DV or mask, thats why we have redundancy

[Elph]

With all those extra redundant systems, don't you end up getting quite a bit bulkier than you would want to be? I know stream-lining isn't everything, but if your equipment is creating an excessive amount of drag, it cuts down on your air consumption efficiency, makes the dive much more tiring and less pleasant.

[DiverMole]

No, cos its all inside the inspirations head, no extra bulk at all

The inspiration has a lovely moulded case that makes it a lot more streamline than a twinset, no valves to roll either

[Inspirationdiver]

Actually Beeger, computers are also responsible for the every minute every day running of the car. A computer controls the ignition timing, fuel/air ratio, throttle, choke, etc. The car's computer has multiple sensors that it recieves input from, including an oxygen sensor in the exhaust, then decides how the engine will run the best in the current conditions. Your car will not run if this computer fails. Do you drive a car? When was the last time your computer failed? Computers and electronics today are much more reliable than they were even ten years ago. I'm not saying that it is okay to completely put your life in the hands of a computer when diving, thats not the situation in the inspiration. The user still has full control over the operation of the unit. The computer just lets you relax and enjoy the dive.

[igotoofar]

You all don't think those pilots are actually flying that plane that takes you to your dive destination!

[spearit]

John J,

Can you run any mixed gas you want through your Inspiration? Trimix, Heliox, TriOx, Nitrox, etc?

[DiverMole]

I can answer that easily. Yes. You can run any gas between 80 and 100% O2 on the O2 side and any diluent you like on the other side as long as its MOD is greater than the depth you are. Normally you want a low O2 mix as the diluent so there is no sense in using notrox on that side

[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.

[Inspirationdiver]

Just to add to John's scenario a little bit. Taking a liveaboard trip to Isle Royale to dive trimix on OC can be quite a hassle. Say you wanted to make 6 dives each all on trimix. Each diver would most likely need three sets of doubles each. They could make one dive on each of the sets, then top them up with air, and make a second shallower dive on each set. For 4 divers on the boat you would have 12 sets of doubles. This really ties up space on the boat, not to mention how much weight that is and how much I love to lug around doubles. Then you need to add travel gas and deco gas for each diver. Probably in steel 72 cu ft cylinders or something similar. I think you get the picture. You can do the same trip on CCR and really reduce the overall hassle. Each diver would only have their CCR unit, and one set of 40 cu ft bailout cylinders each.

[spearit]

"These CCR's are really powerful tools."


I agree. In 10 years, Rebreathers will again change diving and half the divers will be very familiar with them and they will be quite common. In 20 years, everyone will look at OC as archaic. All the nay-sayers will be gone.

John, still have your Dolphin or did you trade that in when you got your Inspiration?