What makes one rebreather "better" than another?

[gobfish1]

whether or not to add o2 . I'd go with .

[Paulo]

Some units are absolutely stupidly designed with 5 cells and a chamois cloth in the lungs to soak up mosture to protect the cells which are stupidly close to the lungs

[dwhitlow]

Or why did you choose your rebreather model over the others available on the market?

Forget marketing shit and 'mine is best' rubbish as they all do the same job which is 'measure pp02 and add oxygen to achieve pre-defined level (aka set-point)'.

Apart from aesthetics (and why would that apply to diving?), and curious ideas like side-mount (it has a place but not in my life), it is really down to how well your choice of CCR is supported locally (things do break and do you really want to export/import this thing?).

I chose an Inspo as the folk I dived with had the same (spares you don't have are helpful) and they are made in the UK so I can visit the factory when I really need attention. I have not regretted that choice and every five years it goes home for a service of everything they deem serviceable . In addition, I do my best to avoid death by pos/neg tests and being very mistrustful about the reliability of my oxygen sensors.

[notdeadyet]

There is no better rebreather. They are all variations on 50 year old technology and the design and engineering "innovation" is minimal. Some, like the KISS, have actually gone backwards during their existence.

For me, the question is what do I want from a rebreather and I made my choices around that. Servicing wasn't really a concern. If you need to send a rebreather back to a manufacturer just for regular servicing if it isn't absolutely, completely fucked then that's a big negative. I wanted to be able to maintain it myself. I wanted a unit that was extremely simple and had been designed with good decision making that made engineering sense because that's where reliability came from. I wanted a unit that suited the diving I was doing which meant BMCL, longish duration scrubber for caving that I wouldn't be getting squeaky balls when it hit 3 hours. My choice did all of that and that's what made it better than other units. Is the actual rebreather objectively better than every other choice? Maybe, maybe not. But it's irrelevant. It was the best unit for my criteria.

Unless you actually know what you want a rebreather to do for you then you are just asking who has the fittest wife.

[RedSeaDiver]

Its interesting isn't it - the reality is that apart from the electronics you could probably build just as good a rebreather with bits from your local big box hardware store.

[Woz]

Its interesting isn't it - the reality is that apart from the electronics you could probably build just as good a rebreather with bits from your local big box hardware store.

Pretty easy to build an mCCR out of plumbing bits, flexible camping water carriers and plastic tubes that held army rockets. I did with a start point of Dr Duncans D5- and learned more about rebreathers doing that than anything else.
Made the display from some acrylic tube with displays inside with a sliding cover that had a magnet in to turn them on and off. Swagelok for the dribble of O2 into the loop. Even made my own ADV by using the guts of an AP AutoAir, similar to what you end up with in a Revo (guts of a Scubapro R190).
The tricky parts are the mouthpiece (Draeger ones are commonly available, or Joki ones for sidemount) and displays (you'll need someone handy with a soldering iron) but none of this is insurmountable.
A homebuild will set you back about £1500-2000 by the time you've added all the bits up. You can get a 2nd hand mono vision for about that now so the impetus to build your own has dropped off somewhat.

[notdeadyet]

Its interesting isn't it - the reality is that apart from the electronics you could probably build just as good a rebreather with bits from your local big box hardware store.

Go on then

That's what every homebuilder thinks at day one. The reality is that you'll end up building every major component five times to get the one version that kind of half works most of the time. If time and money and missed diving opportunities aren't a concern then you can end up with a functional very mediocre rebreather built from off the shelf parts. The good homebuilds are very much the exception and usually people that have some background in engineering or prototyping to start with. There are/were a few very good homebuilders on here. But these are the small minority who end up with something as good as (if not better than) a commercial unit.

Duncan's homebuilds were also the inspiration for me as well. His ideas are great and very innovative, he's a very clever guy. As a hobby, homebuilding is brilliant. It's great doing your first dive on something that was a pile of bogpipe a few weeks earlier. I can only speak for myself and as much as I enjoyed it I really wish I hadn't wasted at least a year fannying about on something that kind of did what I wanted but not quite when I could have just bought a KISS and had a far more capable unit for probably less than what I'd spent. To be honest, it was more the missed opportunities than the money that I regret.

I'd say £2k is a very optimistic estimate. If you know what you are doing, you get everything right first time and don't need a lot of re-work, or building off a stock chassis like an old Draeger or IDA, then maybe.

If you want a unit to dive then just buy a commercial unit.

[MikeF]

Its interesting isn't it - the reality is that apart from the electronics you could probably build just as good a rebreather with bits from your local big box hardware store.

Depends how you want it to breathe and what level of functional safety you want. there's bits of pipe and bits of pipe and too big is as bad as too small before you even start looking at failure modes. If you don't know what you don't know it's going to be a fun ride.

Saying that I looked at a commercial unit the other day in disbelief at the shockingly piss poor design and instantly thought 'how the hell did that get past the most basic of a basic FMECA?' never mind into the market.

it is great fun though,

As said above it's also probably more expensive than just buying a s/h unit

[Wibs]

What utter rubbish - a rebreather never tries to kill you…. All they do is decide whether to add O2 which in actual fact keeps you alive

Not all rebreathers "decide" when to add O2. Some rely upon the fleshy thing driving it making poor decisions

It's safer to assume the thing's trying to kill you, then you know where you stand.

[colinicky]

Not all rebreathers "decide" when to add O2. Some rely upon the fleshy thing driving it making poor decisions

It's safer to assume the thing's trying to kill you, then you know where you DIE.

Corrected that for you

Check my tag line it says it all