which is cheaper, Open circuit or CCR?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

Tienuts

Contributor
Scuba Instructor
Messages
557
Reaction score
127
Location
Grand Cayman
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.
 
Your math looks good. I know just talking recreational gear vs. some of the new rebreathers, the price for gear is getting much closer. For those of us who dive in places where dive times are limited based on there not being much to see and temperature, it would take a little bit longer to break even, but it would still happen.

What about when travelling? Do you take the unit with you and are you able to find bottles easily? Or do you still need to have a complete separate set of gear for travel?

Thanks again for breaking all of that down.
 
Well, you are a man of your word; You said you would, and you did!

Thanks for taking the time to put this post together. I think it's important for divers to analyze the path they are about to take and consider the smartest way to travel it. For someone looking at going tech you've provided a lot of solid data.

We use to go in a cave, drop an AL 40 with 100%, breathe down an AL 80 1/3 and drop it, breathe down another one and drop it and go on back gas. On our way out we would pick up all those bottles and breathe them. That evening we would have to stop and fill our doubles, 2 AL 80s + 1 AL 40, just to do the whole thing again the next day. It wore us out and cost a bundle of money. It's the same game plan for doubles and deco bottles on ocean dives.

Now, with the RB, we drop the AL 40 w/ 100%, drop 1 or 2 AL 80s along the way, and dive. On the way out we just leave them (they're all completely full). Diving Ginnie we'll leave them in all week. And when I go back the next time all of those tanks are already full. Same for my bailout/deco bottles on ocean dives.

Of course, once you start adding HE the equation shifts dramatically. It doesn't take much imagination to see why diving the RB can save time and money.

As icing on the cake, I like having 10 to 12 hours of breathing time just off the RB. That is a pretty big safety plus for me - even more so than the time and money it saves me.
 
Thanks alot for the effort. Its a great anlysis. Given the prices you put for helium are pretty low it breaks even much more faster when the price goes to 1 dollar per cubic.
 
That's amazing, how expensive technical diving is. I did not realize that. Most of my diving is California shore diving above 130 feet on a single tank and on air, and each dive costs me $5 for air.

Adam
 
What about when travelling? Do you take the unit with you and are you able to find bottles easily? Or do you still need to have a complete separate set of gear for travel?

I only own one set of gear. Currently, my international CCR travel has been limited to the Bahamas and Cayman. If I can't take my rEvo, I'm not going. However my gear is compact enough where I can carry on my rebreather, my camera rig, disassembled becomes my 'personal item' under the seat, and I check on clothes, masks, fins, and exposure suits.
 
Most of my diving is California shore diving above 130 feet on a single tank and on air, and each dive costs me $5 for air.

Adam

NDL CC diving provides considerably longer bottom time and less gas than OC even within rec limits of 130' so the comparison is not $5, its $5 x 3 to 6 dives for the same amount of gas and bottom time (plus surface intervals) as a single CC dive.

Tienuts was generous in his calculations for cost of gas - We can pay up to $0.80/CF for O2...

Cost for a 70'/180 minute dive not including bailout/reserve gas...
OC - 440CF 40% Nitrox = 176CF O2 at $0.80/CF = $140
CCR - ~20CF O2 AT $0.80/CF = $16, Sofnolime = $12, Sensor Deprecation (per dive) = $10 = $38

Dwayne
 
Last edited:
Break even on costs will vary with depth a diver descends too, however, I have found two intangibles with RB diving. One is the warm moist air when your diving in the "cool / cold" Pacific Northwest helps keep you warmer. Second is (for me personally) I've found that I don't develop as much mucus production as I do on OC. The net result is ear equalization is much easier and I develop fewer blocks. The cold dry air on OC stimulus mucus production, sometimes blocking the Eustachian tube and causing ear equalization problems. So, for those who love to dive and have ear issues due to mucus production, RB's may help mitigate some of these issues. Just some additional items to consider.
 
I am finding my JJ-CCR costs about AU$12 an hour.

Then again, I am only doing shallow training dives atm. Prices may change slightly as/when I go deeper
 
How did you get a rEvo for 6 grand? Was it used? That seems like a good price. Numbers look good. Deep dives definitely are helping you out.
 
https://www.shearwater.com/products/perdix-ai/

Back
Top Bottom