Looking to Buy a Rebreather

[Wibble]

Relative newbie to CCR racking just 100 hours on my Revo in the past year. Chose it above the others for the dual scrubbers, redundant electronics (Petrel + Nerd), 5 cells, mCCR heritage, leaky orifice, enclosed lungs and size. Am not regretting my choice at all.

However, I intensely dislike its loop water intolerance. I dive "DIR flat" so any liquid in the top/exhale counterung tips back into the exhale loop, round to the mouthpiece and gurgles on exhale. When I've had enough of this I'll empty the loop into the exhale lung and get used to going out of trim (someone called this 'cave trim') -- this is hard as flat trim is a deeply-rooted habit which I've no intention of changing.

This water intolerance needs only a very small amount. Example not crushing/squeezing (a-la accordion squeeze) the water from the loop prior to assembly following a rinse.

It would be wonderful if someone could invent a little water pump button to put in the exhale loop that would pump out a teaspoon of water each press.

Admittedly this doesn't happen very often, but it really annoys when it does. Like last weekend when I stepped off the boat with two ali80s and a scooter and caught my fin on the dive lift as I exited, then fell flat on my face -- idiot!

 

[AJ]

You need to learn to cave dive OC first imo and the cave diving community at large's opinion

There are two opinions on this I believe. Those who have gone the OC -> CCR route believe this is the way to go. Others have gone directly to CCR Tec and Cave and believe this is a fine way to go. I'am not an CCR diver yet, but going to be soon. Because OC D12 is no longer an option for me, I will try the direct CCR route (Tec first). I see no reason to pursue the OC -> CCR route except being comfortable with stages and so on for bailout.

You need to have your skills dialed in for Tec or Cave diving, no matter which gear you use imho. Different ways of diving, not comparable. What I am certain of however is that there is no way to take shortcuts on CCR in a safe way. You can mitigate risks in some ways easier with OC.

 

[Heat Miser]

However, I intensely dislike its loop water intolerance.

Does anyone know how the new Horizon SCR handles water. I heard it had trap/release valve. Is there any chance that technology can be applied to the rEvo?

 

[stuartv]

Relative newbie to CCR racking just 100 hours on my Revo in the past year. Chose it above the others for the dual scrubbers, redundant electronics (Petrel + Nerd), 5 cells, mCCR heritage, leaky orifice, enclosed lungs and size. Am not regretting my choice at all.

However, I intensely dislike its loop water intolerance. I dive "DIR flat" so any liquid in the top/exhale counterung tips back into the exhale loop, round to the mouthpiece and gurgles on exhale. When I've had enough of this I'll empty the loop into the exhale lung and get used to going out of trim (someone called this 'cave trim') -- this is hard as flat trim is a deeply-rooted habit which I've no intention of changing.

This water intolerance needs only a very small amount. Example not crushing/squeezing (a-la accordion squeeze) the water from the loop prior to assembly following a rinse.

It would be wonderful if someone could invent a little water pump button to put in the exhale loop that would pump out a teaspoon of water each press.

Admittedly this doesn't happen very often, but it really annoys when it does. Like last weekend when I stepped off the boat with two ali80s and a scooter and caught my fin on the dive lift as I exited, then fell flat on my face -- idiot!

It is not the factory recommended practice, but I have learned to cut a factory absorbent pad in half, roll that up, and put it in the bottom of the exhale lung. That seems to pretty well eliminate any issues with gurgling.

 

[macado]

Does anyone know how the new Horizon SCR handles water. I heard it had trap/release valve. Is there any chance that technology can be applied to the rEvo?

I have only seen one in person very briefly but the water tolerance on the Mares Horizon *should* be much greater than a normal rEvo. The exhale counterlung acts as one giant water strap and there are dump valves located on the bottom of each lung (according to the manual)

They must not teach de-watering in the class as the Horizon manual recommends not to pull dump valves or risk flooding the unit.

If they ever make a rEvo IV I hope they use this lung configuration. In theory it should add some flood tolerance to the rEvo.

https://www.revo-rebreathers.pl/images/files/09-15835-Mares-OM Horizon - web-ENG.pdf

EDIT: This is not an endorsement for the Mares Horizon Personally I think recreational rebreathers should not really be a thing.

 

[broncobowsher]

There were lots of good points brought up so I'm not sure I'm going to add much value here but I'm happy to give some input. I own a rEvo, SF2, and most recently a Defender which is the cousin to the X-CCR (Hammerhead platform).

I can't unfortunately speak on any of the KISS rebreathers but they are popular units. The biggest complaint I hear is build quality and flood tolerance. Unfortunately there doesn't seem to really be a good alternative to the Sidewinder so people seem to just deal with it's flaws. Personally I don't think a sidemount CCR is the best first rebreather. I have friends that dive KISS classics and we've done lots of dives together but I just think there are better units on the market.

I originally started on a rEvo mCCR and put about ~850 hours on it. It was my first rebreather and we had a lot of fun adventures together. I dove the sh*t out of it. I still like my rEvo but for me the Achilles' heel was lack of flood tolerance. For this reason alone I don't feel it's the best unit for cave diving although others would certainly disagree. There are some good features on the rEvo such as dual scrubbers, smaller profile and ease of assembly. I'm also a fan of the fully redundant electronics and 5-6 O2 sensors options but some people find this "gimmicky."

The other thing that really annoyed me was rEvo's "Apple" like philosophy of not wanting users to open the case. It was the policy of rEvo USA to not sell counterlungs to the end user. Granted this is not a simple install for the average user but I firmly believe users should be allowed to service their own gear. My counterlungs in my rEvo are a combination of tear-aid/aquaseal holding them together but they don't leak anymore. My unit was also old (original rEvo II) and had 2 previous owners prior to me so it had a lot of mileage.

With the exception of the counterlungs / internal bulkhead gas fittings the rEvo is extremely self serviceable. None of the electronics are potted. There is really no "head."

There was some uncertainly about rEvo support when Mares took over. I can't speak for last couple years but it seems like parts and servicing is not an issue. It WAS an issue when Ocean Edge handled rEvo servicing. I think ultimately maybe the Mares distribution is a good thing. I lost exactly 1 dive on my rEvo due to O2 leak. I never had to bailout and I never fully flooded the unit although I did get a lot of water in it once when I was brand new.

There is a lot of rEvo hate/drama on Scubaboard. Mainly I think because of the AddHelium/Peter Sotis debacle and because of a few high profile cave instructors in Florida who simply hate the rEvo and people like to follow the herd mentality there. It's really popular to hate the rEvo and joke about it's 11 ridiculous oxygen sensors. Some of it is deserved; there are some definite improvements that could be made to the aging design.

After the rEvo I bought an SF2 and put ~350 hours on it. I wanted to go full eCCR and I wanted a unit that had good flood tolerance for longer duration cave diving. Personally I think the SF2 is one of the easiest units on the market to de-water. The SF2 is streamlined and less "busy" than some other units. By that I mean everything is housed in the carbon fiber body.

My biggest issue with the SF2 is work of breathing and uncertainly about future USA support. ScubaForce USA has changed management/ownership about 5 times in 6 years. There is currently no way to get your head serviced in the US and all the electronics are potted inside.

The unit breathes great in trim but not when you're in an extreme heads up position (waiting on surface for a boat) or going completely head down through a restriction. I don't believe the SF2 travels well. It breaks down into smaller pieces but the latches on the canister body really prevent it from breaking down any smaller.

One thing the SF2 has going for it is that it's incredibly easy to assemble and a very simple design but there are some pieces I don't like. The head is a pain in the ass to get off without their special "head removal" tool or standing over it and/or pulling on vulnerable fittings. The SF2 head design is also literally two pieces that are silicon glued together. It's a crappy design and the head is prone to leaks there although they wont admit it.

The unit is also very long/tall compared to other units. As someone who is short the unit is comically long on me. It's not an issue per se but I wish it were shorter. They do make a smaller size lower section (I guess for women with smaller tidal volume) but it decreases the counterlung volume by an additional 1L. I could not get a full breath when I tried it and bottomed out the lung every breath.

I also hate how high the head sits on the unit. It's basically the first thing to hit on a cave / wreck ceiling. It's 100% non-issue but I just have a lot of nice scratches there. You need to train yourself to duck if you're used to doubles or another rebreather.

The SF2 DSV is a piece of crap. It should be replaced immediately with something else. I put a Divesoft DSV on mine.

The SF2 tank brackets are a poor design. They bend and wobble. The welds failed on mine and I had to weld them back together.

I also wish the SF2 came stock with a HUD but this is easily rectified. I ran my unit with two Shearwaters (one controller and one hardwired monitor) because I believe every unit should have two ways to monitor the loop. I did not jump on the Shearwater NERD bandwagon because I personally like two handsets better. I wish it had another monitoring port.

I realize I was pretty negative on the SF2 in my post but I still think it's a decent unit. No CCR is without it's faults.

Right now I am brand new on my Defender but so far I really like it. I can't really give a solid opinion of pro/cons until I get more hours. The bayonet head fitting and quick-lock connectors that go to the loop hoses/BOV/head are amazing. I wish these were on every rebreather. I know this is nothing new for Hammerhead users but I really like this design. To be honest-I just happened to pick up a brand new Defender (used but never in the water) for a good price so I jumped on it since I wasn't finding used X-CCRs or JJs in price range I wanted without a significant amount of hours.

All the iQsub parts seem well engineered (I'm sure somebody will laugh at me for saying that.) I love the cable connectors on the head and I really love the removeable cell cartridge.

X-CCR / Defender takes numerous size scrubbers (4.5lbs/5.5lbs/8lbs and even 9lb for the Defender). I'm still struggling to get used to limited head movement due to the T-pieces but I think that is similar for most units like this. For example: JJ, Meg.

I really love the manifolds that attach to the back of the canister for hose management. It makes the routing for the MAVs, BOV, wing, and O2 feed into the head really clean.

The unit breathes well in most positions compared to SF2. De-watering the exhale lung seems straight forward but not quite as easy as the SF2. I'm just not in a great position to judge this yet.

Compared to my rEvo and SF2 I feel the assembly is much more involved process with T-pieces/counterlungs, BOV connection, etc but it's really not bad and I think after another 20 builds or so it will all seem really irrelevant.

Some last thoughts - Everybody seems to tout a rebreather as a solution to underwater photography to get "closer" to larger pelagics or not scare the fish but I honestly just don't see it. I've had some pretty amazing encounters on open circuit. I think most of it's just being in the right place at the right time. Personally I think rebreathers are more of a hindrance to photographers who tend to be more focused on their camera and spend less time being attentive to their ppO2 and what their unit is doing. That's not to say it's unsafe but it just requires a lot of attention and task focusing to do both.

I also used to think that I would dive a rebreather every dive and that was true for maybe my first couple years until I built enough hours to feel comfortable/proficient. Honestly for 2.5 hour Ginnie Springs (~100ft) dives I am just happier with open circuit doubles with a stage or two.

I now only really dive a rebreather if I want to do a 2.5-3+ hour dive or a dive that requires a decent amount of trimix (130ft/40m+) or one with a significant amount of decompression. A lot of my dives are ocean wreck dives in the 150-250ft (~45m-76m) range so I dive a rebreather. On the other hand last week I was on a small wreck in 110ft so I dove open circuit

TL;DR - Sorry for wall of text. Everyone has strong opinions about the best rebreather. They all do the same thing. They all suck.
My top three picks (in no particular order) would be X-CCR/Defender, JJ and maybe a Tiburon with BMCLs. Fathom would be runner up 4th but the company is one person and there are only like 60-70 of them in the world.

Nice walk through. Descriptive without bashing. Yes, they are all flawed. Just different flaws for different reasons. Some people get fixated on a single flaw and can't see that it really isn't that big of an issue and there are a lot of other good features about a particular brand/model of rebreather.

Most rebreather owners are fan boys of what they have. Put the blinders on to any other options, ignore the flaws, ignore that someone else might want to dive in a different situation then themselves.

I find myself diving the rebreather exclusively now. Not because it is better, but just to stay fresh with it. It is the least economical way to dive (until you are over 150' and running a good mix of Helium).

 

[rddvet]

There are two opinions on this I believe. Those who have gone the OC -> CCR route believe this is the way to go. Others have gone directly to CCR Tec and Cave and believe this is a fine way to go. I'am not an CCR diver yet, but going to be soon. Because OC D12 is no longer an option for me, I will try the direct CCR route (Tec first). I see no reason to pursue the OC -> CCR route except being comfortable with stages and so on for bailout.

You need to have your skills dialed in for Tec or Cave diving, no matter which gear you use imho. Different ways of diving, not comparable. What I am certain of however is that there is no way to take shortcuts on CCR in a safe way. You can mitigate risks in some ways easier with OC.

I won't go into it in much detail, but specifically for cave diving I don't believe it's a wise idea to have your first experience diving oc in a cave be as you bailout. There are nuances to cave diving that vary slightly between oc and ccr. I was cave certified for almost 10 years before I went to ccr cave. I'm very glad I didn't start as a ccr cave diver. I've been helitrox certified for a while and plan to move to full trimix soon (only held off due to having a pfo). Rather than learning on the ccr, I'm taking oc trimix (tech 1) because I and most of my mentors believe in both tech and cave diving you need to hone your skills first on OC. But those are just my opinions based on my experience. I will leave it up to any instructors who want to wade into the waters of that discussion. I think in N. Fl you will find 90+% of instructors would tell a student to go OC first.

 

[stuartv]

I find myself diving the rebreather exclusively now. Not because it is better, but just to stay fresh with it. It is the least economical way to dive (until you are over 150' and running a good mix of Helium).

Even that depends, I think, on where you are and how much fills cost.

At Olympus Dive Center (Morehead City, NC), a Nitrox fill of an HP100 is $14. For 2 days of 2 tank recreational diving, that is $56.

I only use trimix for dil in my rEvo, and I can still dive those same 4 dives for a LOT less than $56 worth of gas and sorb. Really, I could do those 4 dives with 1 set of 3L cylinders and only packing the scrubber once. Off the top of my head, that would be less than $30? And if I used air for dil, even less.

 

[stuartv]

There were lots of good points brought up so I'm not sure I'm going to add much value here but I'm happy to give some input. I own a rEvo, SF2, and most recently a Defender which is the cousin to the X-CCR (Hammerhead platform).
[snip]

Thanks for posting that. Excellent to get some thoughts from somebody who owns a rEvo and other units.

I do have some questions/thoughts.

First, the rEvo did not make your Top 4. Is that just because of the flood (in)tolerance? Or also factoring in what you called their Apple style of not letting you do certain repairs yourself? Or more to it in feeling like those Top 4 of yours are preferable to you over the rEvo?

On the rEvo flood tolerance, have you had legit problems with your rEvo that would have been a non-problem if you had a way to de-water it? How many times have you had to end a dive early because of water in the loop, where you could have continued if you could de-water? I'm asking because I'm still trying to understand how big of a problem the rEvo "flood tolerance" really is. Is it a problem on paper? Is it a problem that screws people over often? Or is it a problem that causes 1 dive in 1000 to be ended early and that's about it? Here, I'm just trying to understand your personal experience with this issue.

You mentioned that none of the rEvo electronics are potted. I would have said all of my rEvo electronics are potted. The "brain" circuit board is potted inside the battery box. The O2 and solenoid boards are each potted inside the modules that live in each of the counter lungs. But, my unit is a hybrid, with DiveCAN, a solenoid, and rMS. You said you have an mCCR, so yours is fully manual. No DiveCAN, no solenoid, and no rMS. Is that a difference between the rEvo mCCR versus hCCR/eCCR?

Regarding u/w photography, my experience is definitely different than what you described. I have had a number of encounters that I feel strongly would not have happened on OC. Also, I did a fair bit of photography on OC doubles before I moved to CCR. To me, the biggest advantage of shooting on OC is the ability to completely control buoyancy and position in the water without using your hands. Need to elevate 6" to get The Shot? No problem on OC. Not so easy on CC. But in contrast, on CC I never have to pause what I'm doing to check my SPG or NDL. Everything is right where I can see it in my NERD. And with the hCCR unit, I don't even have to take a hand off my camera to inject O2 ever.

For u/w photography, I think I would ALWAYS choose to dive my CCR over diving OC. But, really, I'm still at the relatively new stage where I would always choose to dive my CCR, in any/every situation I could... And I have no trouble admitting that I feel like my CCR buoyancy still has a long way to improve, and that is part of why I want to dive it as often as possible.

 

[Wibble]

Revo potted electronics...

If you completely flood the unit, e.g. loop was severed, you'd (obviously) loose the cells, but aside from cleaning the connectors, nothing else would be lost.


Revo III lungs: one benefit of the Revo is being able to wipe down the lungs and clean out the lung butter and properly dry them out.

Do think I need to look into having a cloth in the exhale lung. Thus far have resisted as I really don't want something that could interfere with the ADV should the cloth move around.