Is a CCR more expensive than OC? I took the last 2 months of my dive log, and broke them down to make an interesting comparison on the costs of diving closed circuit versus open circuit. It's something I've always wanted to compare, but never got around to doing.
In the past 2 months, I did 21 dives total.
6 dives above 130
4 dives 130-200
6 dives 200-280
5 dives 280-350
All of these dives were conducted on my rebreather. For those unaware, the cost of diving CCR does not vary based on depth, so a 30 foot dive, costs me the same as a dive to 400 feet. The cost of diving the CCR is broken down by the hour. 1 helium diluent fill, and 1 oxygen fill cost $10, and will last me 3 hours. 1 sorb cassette holds 3lbs of sorb, and will get me 3 hours in warm water. Sorb costs $129 for a 44lb jug, which breaks down to about $3.25 per hour. For those following with their calculators, I've accounted 4lbs for waste, and spillage. This means the rEvo costs me about $7 per hour to dive. Also to add yearly expenses on maintenance and cells, and since on many dives I use fresh fills/sorb regardless of how much time I have left, let's double that figure to $14/hour.
Obviously with an OC diver, the gas needs to be appropriate for the depth you are diving to. 2 scenarios exist, one you own a single set of doubles, and you drain them and fill them with the appropriate mix each time. The second scenario is you own multiple sets of doubles, (adding gear expense) and you top off the appropriate mix each time. If you're fortunate enough to live near a shop that banks trimix, you can do option 2, but most other locations as I am aware, require you to drain them for filling trimix. For the purposes of this comparison, we'll assume you're filling the same set for each dive, and hence must be drained each time.
All of my dives above 130 were long enough profiles where I could not conduct on a single cylinder. (Not with an acceptable air reserve anyway.) However for this comparison, we'll just assume each 130 foot dive is a recreational, single tank profile.
For the dives above 130 feet, would require a single cylinder filled with 32%. A typical nitrox fill around here is $10 per tank.
For dives in the 130-200 range would require a fill of 21/35 at .35 per cubic foot, plus a fill of a deco gas, lets say 40 cubic feet of 50% at .35 per cubic foot. This makes the total for this dive $84.
For dives in the 200-280 range, I'd use 15/55 at .55 per cubic foot, plus 40cf of 50% and 40cf of O2, for a total of $138, and dives in the 280-350 range are a similar price for the gas.
So had I dove the past 2 months on open-circuit, I would have spent $1,914 on gas. Doing the same dives on my CCR (31 hours 41 minutes in total,) based on the above figures would have been $439.74 on fills and sorb. In reality is was much lower.
So how long until the rebreather pays for itself? Well, using a popular tech diving website, I added up the cost of a new OC tech diving rig, to include expenses like tanks, bottom timers, regulators, doubles wings, and deco bottles. I left off items that both divers would need, such as lights, masks, fins, etc. According to this website, the cost for all of this was $5204. Let's take 20% off this figure to be fair, and because people will say that no one buys all their stuff new. So we'll call it $4100.
My rEvo mCCR cost me $6633 for the complete unit. Cylinder were another $500. My bailout bottles were from my OC days, but I figure them new to be $562 each when new (x3.) This makes my total CCR investment $8,819. Plus training ($2000) brings the total to $10,819. To be fair, lets add another 20% for all the gadgets, and add-ons I've tried and purchased over the years, and for cell replacement. This brings my grand total to just under $13,000. The difference in my sample OC investment, and my CCR investment is roughly $8,900.
If we examine the example I gave above, we find the difference to be about $740 per month. Now granted, my past 2 months have been very active, more so than normal. So let's average out the good months and the bad months by halving the figure, which makes the savings about $370 per month. In this example, I pay off my CCR investment in 24 months.
In the past 2 months, I did 21 dives total.
6 dives above 130
4 dives 130-200
6 dives 200-280
5 dives 280-350
All of these dives were conducted on my rebreather. For those unaware, the cost of diving CCR does not vary based on depth, so a 30 foot dive, costs me the same as a dive to 400 feet. The cost of diving the CCR is broken down by the hour. 1 helium diluent fill, and 1 oxygen fill cost $10, and will last me 3 hours. 1 sorb cassette holds 3lbs of sorb, and will get me 3 hours in warm water. Sorb costs $129 for a 44lb jug, which breaks down to about $3.25 per hour. For those following with their calculators, I've accounted 4lbs for waste, and spillage. This means the rEvo costs me about $7 per hour to dive. Also to add yearly expenses on maintenance and cells, and since on many dives I use fresh fills/sorb regardless of how much time I have left, let's double that figure to $14/hour.
Obviously with an OC diver, the gas needs to be appropriate for the depth you are diving to. 2 scenarios exist, one you own a single set of doubles, and you drain them and fill them with the appropriate mix each time. The second scenario is you own multiple sets of doubles, (adding gear expense) and you top off the appropriate mix each time. If you're fortunate enough to live near a shop that banks trimix, you can do option 2, but most other locations as I am aware, require you to drain them for filling trimix. For the purposes of this comparison, we'll assume you're filling the same set for each dive, and hence must be drained each time.
All of my dives above 130 were long enough profiles where I could not conduct on a single cylinder. (Not with an acceptable air reserve anyway.) However for this comparison, we'll just assume each 130 foot dive is a recreational, single tank profile.
For the dives above 130 feet, would require a single cylinder filled with 32%. A typical nitrox fill around here is $10 per tank.
For dives in the 130-200 range would require a fill of 21/35 at .35 per cubic foot, plus a fill of a deco gas, lets say 40 cubic feet of 50% at .35 per cubic foot. This makes the total for this dive $84.
For dives in the 200-280 range, I'd use 15/55 at .55 per cubic foot, plus 40cf of 50% and 40cf of O2, for a total of $138, and dives in the 280-350 range are a similar price for the gas.
So had I dove the past 2 months on open-circuit, I would have spent $1,914 on gas. Doing the same dives on my CCR (31 hours 41 minutes in total,) based on the above figures would have been $439.74 on fills and sorb. In reality is was much lower.
So how long until the rebreather pays for itself? Well, using a popular tech diving website, I added up the cost of a new OC tech diving rig, to include expenses like tanks, bottom timers, regulators, doubles wings, and deco bottles. I left off items that both divers would need, such as lights, masks, fins, etc. According to this website, the cost for all of this was $5204. Let's take 20% off this figure to be fair, and because people will say that no one buys all their stuff new. So we'll call it $4100.
My rEvo mCCR cost me $6633 for the complete unit. Cylinder were another $500. My bailout bottles were from my OC days, but I figure them new to be $562 each when new (x3.) This makes my total CCR investment $8,819. Plus training ($2000) brings the total to $10,819. To be fair, lets add another 20% for all the gadgets, and add-ons I've tried and purchased over the years, and for cell replacement. This brings my grand total to just under $13,000. The difference in my sample OC investment, and my CCR investment is roughly $8,900.
If we examine the example I gave above, we find the difference to be about $740 per month. Now granted, my past 2 months have been very active, more so than normal. So let's average out the good months and the bad months by halving the figure, which makes the savings about $370 per month. In this example, I pay off my CCR investment in 24 months.