Rebreather - Cost of Ownership

[kensuf]

Sorry Tom. There's too much stupid here, I need to correct.

Cells - replace them when the manufacturer expiration date has hit, OR when they are failing (whichever comes first). Treat them like the life support they are -- would you give your child expired medicine? Hell no, so why would you mess around with life support equipment?

Sorb - sorb is $3.00 per pound at RETAIL prices. A full 5.5# scrubber is $18. Replace it whenever you're going deeper than 150' (compressed CO2 molecules shortening the dwell time IS a thing. I've watched a friend of mine take a full on CO2 hit in a 9# scrubber that "only" had 3 hours on it, it WAS not pretty), OR whenever you've used up "2/3rd" of the time on it, whichever comes first. For a 5.5# scrubber, even if you're diving in 60' of water, dump that crap after three hours. Pushing it for a full 3x 2 hour dives is only saving you $6 worth of unused sorb.

I've been dumping my scrubber at the end of the dive day, every time -- does it suck if I've only done 2 hours on it? Sure, absolutely. But you know what sucks more? Taking a CO2 hit.

I'll agree to a point with o-rings and mushroom valves, but really, we're talking $20-30 in soft parts to do an annual service, so I'm not sure what the big concern is there.

Remember, we take prudent actions because we care about our families and friends. If we die doing something stupid, it really won't matter to us (because we're dead! it's only your undead self imagining you being dead that cares, once you're dead you won't care anymore) - but we will leave behind our family and friends, and they will suffer for our dumb actions. I think of my wife every single time I toss unused scrubber or replace cells that are reading decent mV's but are at the 12 month limit.

This is something that @victorzamora and I got into some pretty heated arguments for literally years about.

• Cells-you don't actually need cells annually. You need cells when you need cells. Budget for them annually, but some may go 4 months, some may go 24 months. Don't replace cells until they need to be replaced, same as rebuilding regulators every year. Rebuild them when they need it.
  • Budget $250
• Sorb/gas-need a full scrubber when you need a full scrubber. If you are doing 2 hour dives, that 2-3 dives depending on scrubber size. A recent study was done that says partially used sorb can just sit around for months and be just as good, if not better, than it was when you finished the first dive. Budget a pound an hour and you're saying 20 technical dives, but you'll use the CCR for most everything at least for a while. 20 tech dives@2hrs=40hrs so round up and say 100hrs/yr. Gas use is about a liter/minute of O2 and Dil which rounds up to say 300cf of each.
  • $400 in sorb
  • $150-300cf of O2 at rounded up Amigos pricing *$0.46/cf*
  • $200-300cf of 18/45 at rounded up Amigos pricing *50/50 of $0.17 EAN32 and $0.96 helium*
• The o-rings and flapper valves don't need to be replaced annually, and if you're smart you'll find the sizes and buy them in bulk. Maybe $50/year if you over buy them, and then you'll have to service the two extra first stages every couple of years, so budget $50/year in reg rebuilds.
  • $100/year
• $300 in miscellaneous fills for deco/bailout bottles or the random open circuit dives, etc.
• I won't include any open circuit stuff because you will need it for both situations, so this list is "in addition to my normal OC stuff".

So roughly speaking, you'll be shelling out $1400 in consumables for the rebreather. You'll pro Ish, but that's for 100 total hours of diving. Right now you're saying 20 dives/year which is probably around 40 hours, and it's costing you around $2500/year in gas bills, not including any non-technical diving that you're doing. It will save you roughly a grand a year given your current diving habits *with a LOT of assumptions so don't quote me on any of it. Your gas pricing may be higher than Amigos pricing by more than what I rounded them up to which is the only one that would make it super wonky. Everything else is pretty conservative.

Saving $1k/year in dive costs then has to outweigh the buy-in price. You're in for $10k in a brand new CCR with Mod1 training. Probably $12k if you go the GUE route with the GUE-JJ *I have no idea what that actual cost is*. Add another $1500 for redoing normoxic trimix since you can't use OC normoxic as a pre-req for hypoxic *which is retarded, but whatever*, then another $1500 for hypoxic.
If that investment pays off, then you can justify the rebreather on gas savings. Saving $1k a year though doesn't do much for you. If you increase the trimix dives because it isn't so cost prohibitive and go from 40hrs to 100hrs, then you're now saving almost $5k/year in helium and it's a no-brainer. If you want to justify it based on other factors like extra warmth, silence, no tick-tock from the SPG, cool factor, etc etc. then do that. It won't cost you more/year than diving open circuit trimix, but it's a long ROI at 20dives/year

 

[kensuf]

My quick annual cost estimates..

1. Unit - $8000 (I currently own three different units, each was around $8k, don't tell my wife please).
2. Cells - $320 per year per unit (I figure 4 cells a year for a unit that needs 3 cells. I also do the 3-4 month rotation bit, I'm anal about my cells).
3. Sorb - $18 per dive day. Actually, I pay a little less because I buy in bulk, but yeah that.
4. Fills - $4 for oxygen, $4 for air, $3-5 per dive day for DIL top-up.
5. Maintenance - $20-30 in soft parts.

 

[tbone1004]

@kensuf is expiration the date on the cell is it the date that the rebreather manufacturer or training agency specifies? Those are two different dates... I'm anal about my cells, but not about the date that's printed on the side of them, only their performance characteristics. If I see one starting to go sideways, it gets replaced, but I'm certainly not going to throw a cell out that's been out of the bag for 2 months because the training agency says it was expired. Especially since those cells are used in the medical field and have ridiculous shelf lives for CYOA policies. Be smart about your cells and replace them when needed, they may not make a single dive, they may last 18 months. That's why I think it's important to know and understand how they work instead of blindly replacing perfectly good devices. My regulator manufacturer suggest 2-year service intervals, if my regs don't need rebuilding, I don't rebuild.

Of note, I don't start a dive with a scrubber more than 50% used, but that's interesting about the hit your buddy took. Did he check the packing before that dive? That is the one thing that makes me nervous with reusing scrubbers is settling that occurs during transport. I dump at the end of a trip regardless of where it is, but if I came down and did a single afternoon dive that was 90mins long, I'm not going to repack for the next day. I'll check it during assembly and make sure it's still packed properly though. Settling is very real and I've had some scrubbers settle funny in the ride over to the dive site if it was particularly bumpy.

The $20-$30 isn't something I object to, paying someone $200 to overhaul a rebreather every year is. If you DIY like you should, then happy days, but a lot of people will send the unit back for a factory service every year which I think is ridiculous.

 

[kierentec]

I adamantly agree with Ken here. Suggesting to push cell life past expiration date is hazardous and there are several fatalities and near misses where VERY experienced divers and instructors did just that. Replace your cells, you’re family is counting on you to do so.

Sorry Tom. There's too much stupid here, I need to correct.

Cells - replace them when the manufacturer expiration date has hit, OR when they are failing (whichever comes first). Treat them like the life support they are -- would you give your child expired medicine? Hell no, so why would you mess around with life support equipment?

Sorb - sorb is $3.00 per pound at RETAIL prices. A full 5.5# scrubber is $18. Replace it whenever you're going deeper than 150' (compressed CO2 molecules shortening the dwell time IS a thing. I've watched a friend of mine take a full on CO2 hit in a 9# scrubber that "only" had 3 hours on it, it WAS not pretty), OR whenever you've used up "2/3rd" of the time on it, whichever comes first. For a 5.5# scrubber, even if you're diving in 60' of water, dump that crap after three hours. Pushing it for a full 3x 2 hour dives is only saving you $6 worth of unused sorb.

I've been dumping my scrubber at the end of the dive day, every time -- does it suck if I've only done 2 hours on it? Sure, absolutely. But you know what sucks more? Taking a CO2 hit.

I'll agree to a point with o-rings and mushroom valves, but really, we're talking $20-30 in soft parts to do an annual service, so I'm not sure what the big concern is there.

Remember, we take prudent actions because we care about our families and friends. If we die doing something stupid, it really won't matter to us (because we're dead! it's only your undead self imagining you being dead that cares, once you're dead you won't care anymore) - but we will leave behind our family and friends, and they will suffer for our dumb actions. I think of my wife every single time I toss unused scrubber or replace cells that are reading decent mV's but are at the 12 month limit.

 

[tbone1004]

@kierentec Not that I didn't suggest to push them. I said replace them when they need replacing. Why is there no objection to ignoring regulator service intervals and instead servicing them when they need to be serviced, but there is on cells? If we are learning how the cells work, how to track linearity, how to check for current limiting *which you need to because a lot of cells fail BEFORE the expiration dates*, then what does a magic number on a sticker or even more idiotic number from a training agency matter?

 

[rddvet]

@tbone1004
Thanks. Using the soft ones feels not strong enough, though easier. Just trying to look at all the options people use before I throw down money.

Cells - replace them when the manufacturer expiration date has hit, OR when they are failing (whichever comes first). Treat them like the life support they are -- would you give your child expired medicine? .

PS-not a good example. Chelsea says that at the ped's office she worked at people give grossly outdated meds to their kids all the time, and I see the same thing at my job. You and I just happen to not be the "general public" who do it all the time.

A few months back I had asked about cells and the cell manufacturer expiration date because I hear 50/50 the extremes seen here : don't exceed 12 months or manufacturer's recommendation vs don't change them unless you have to (if you're testing them for current limiting/linearity regularly).

 

[oya]

Tom, there's a phrase already in place for what you're espousing here:

Normalization of deviance.

It kills people.

Stop.

 

[rddvet]

BTW-to the OP- I get trying to justify the cost of going CCR, but if we're all trying to justify the costs of diving, then we should just all give up. It's all about our enjoyment, so look at it that way. I didn't need to learn to dive, or learn to technical dive, or move to a ccr, but I wanted to. Actually, I never really wanted to move to CCR, but my wife's scientific pursuits require one which eventually piqued my interest (if she needs a new toy, so do I). Now that we're on CC, I really enjoy it and prefer it to OC. I can not justify the costs. We can all create spreadsheets and give you ideas of long term costs, but honestly it will vary from person to person based on both the diving you do and choices you make (ie like I recently bought an extra set of 50s because I want to try my unit "GUE style"). At the end of the day, do you want to learn to dive CC?

I also can't justify the cost of my fill station monetarily. I started with a big compressor, added more and more components, and within the year added a brand new electric booster. Between the 2 CCRs and my fill station, I could buy a really nice car. But I justified the fill station by being self-reliant. My wife and I drive 2-3 hours each way on sundays to dive. We would wake up at 5 AM, hit the road, dive, then need fills before heading home. We'd waste at least an hour at the dive shop, then rush home so we could take care of our dogs. It got to be annoying, especially when you'd get bad fills or things like a fill monkey closing the isolator and only filling one tank. So, I made the personal decision to make a fill station. I don't regret the decision one bit. Now that I'm diving almost exclusively CCR, I rarely run my compressor and could just live with the booster alone, but I don't want to, so I keep it. It's all about personal choices/wants.

If you start to tally up what technical diving costs annually or over your life, it will make you realize you've made a really dumb financial decision over the years, but it's a hell of a lot of fun.

 

[tbone1004]

@oya
Roger, going to agree to disagree on what I'm espousing, since it is not normalization of deviance and I believe it is actually quite the opposite, but I will drop the argument.

@rddvet you bring up a good point. The spreadsheets may justify the cost of a vs b, but it's still a scary big expense to do the types of diving we all like to do, and even scarier when you add up the total equipment cost. Every time I load up my fairly nice and relatively new big SUV, which is comparably as new and nice as yours, I cringe thinking that all the equipment inside is worth that much more....

 

[kierentec]

@kierentec Not that I didn't suggest to push them. I said replace them when they need replacing. Why is there no objection to ignoring regulator service intervals and instead servicing them when they need to be serviced, but there is on cells? If we are learning how the cells work, how to track linearity, how to check for current limiting *which you need to because a lot of cells fail BEFORE the expiration dates*, then what does a magic number on a sticker or even more idiotic number from a training agency matter?

Of course track linearity and check for current limiting, I never said ignore that. What you are suggesting is ignoring an important component in oxygen sensor chemistry, TIME. YES, many cells will last longer than the manufacturer's recommendation, but the important thing to remember is that the failure rate starts to increase exponentially as cells age. Trust me, the manufacturers aren't trying to "trick you" into buying new cells to make a few dollars (diving isn't even a blip on the cell manufacturer's radar, we are very fortunate they sell to us to begin with). They are trying to save themselves millions of dollars when you tox and drown and your family sues them.

I have a few important goals each time I prepare to get into the water, but most importantly is getting back to the surface alive. It never includes trying to prove manufacturers wrong or save a couple hundred dollars a year. There have been many divers and instructors who thought they were smarter "than the man" (but in the end proved to just be lazy or cheap) who paid the ultimate price when they stretched their cells. To the point now, where it's just absolutely asinine to think anyone could actually advocate it.

Don't dive expired cells. My friends don't want to drag your body out of the water.