Considering a Rebreather....

[Diving Dubai]

Had you asked me the question a year ago the answer would have firmly been no, but for whatever reason I'm thinking about the possibility of moving on to a re breather.

I'm not currently Tri Mix certified, and although I do dive mixed gasses for accelerated deco, it's only to around 40m and less than 10 of those dives a year.

So far it's a 2 part process. the first has been asking myself the questions of not so much why I may want on, but more do I have the correct mindset for one. I appreciate that fatalities are generally down to the human error and that there are no short cuts and corner cutting in check lists. There may be more pointers that you guys can give me.

I've been around rebreather divers for a few years, so appreciate the basic workings, but after that it seems hard to get a grasp on it.

Those here I know all dive Inspirations. I presume the majority have decided to all have similar models to share knowledge and parts. I need to chat with them, but of course but here I'm expecting a less biased answer.

But how do you decide which rebreather to choose? Just looking looking at say the Inspiration, Optima, REvo etc. Where do you start?

I do have an appreciation of some of the terms but no way an understanding.

Should you have an ADV? what about BoV? Counter lungs affecting WoB? From mounted back mounted what is best... Would a complete newbie even notice the difference between the 2? Is having Shear water electronics important or are the manufacturers systems preferred?

As I mentioned above I have an appreciation but not an understanding so if your answers could be aimed at the layman level rather than assuming prior knowledge, I'd be grateful.

 

[Caveeagle]

I love the technology and hope to go this route at some point. For now it does not make sense. I am hoping the new innovation will make these units more reliable and with lower operating cost. ie: the Poseidon solid state sensors.

 

[rjack321]

I would start by identifying what you can get trained on and support/parts. The "best" CCR in the world isn't so great if there's no training or support short of going 1/2 way around the world. (from Dubai, Optima might be in that category)

Second big decision is what are your friends diving and why? There's a lot to be said for having a support structure of similar buddies.

After that I would do some try dives and read a lot. Everything is a compromise in some way, there is no "best" although there may be a best for you.

 

[bumcikaz]

Just see what instructors are around for which units, dont leave out meg and hollis rebreathers

 

[bl6394]

My shop is an APD Dealer. One of the other instructor's at my shop is an APD Instructor. He had a used Evo at a good price. There is a community of other Evo divers here in St. Louis.

Generally - the availability of instruction, service and consumables are important considerations. Given the advantages that APD had in my local market - it was pretty compelling.

With that said - three months after the purchase - the head - which had been checked out by SD as part of the sale - developed cracks around the solenoid. Something that has happened to a lot of the 2006 Evolution lids. The repair was a new lid $$$ and a three month wait while the unit was sent back to the UK for service.

Outside of the repair, I like many of the APD's features. I don't like the APD's harness and have mixed feelings about the tek frame. Not thrilled about the length of time for a repair or the fact that the HUS upgrade seems to be indefinitely unavailable due to supplier issues.

There's a good chance that whatever rebreather you start diving - will get replaced with something else when you have some hours under your belt. I also really like what I've seen of the Meg - and may go that way down the road.

My used unit had an ADV - which I like. But I also practice flying manually from time to time. It also has an OCB (Open Circuit Bailout Valve) - which I like in case I need to bailout during a CO2 hit. My unit had the OTS counter-lungs - which are OK. But, I don't like all the clutter on my chest - and would like to try the BM CL sometime.

Check out Mel Clark's book, "Rebreather's Simplified." It gave me some background information when I was deciding which unit to purchase.

 

[doctormike]

I don't know if JJ training is available where you are, but don't forget to check it out. Very solid and beautifully engineered machine, simple and straightforward assembly, but certainly capable of big dives, if you ever get there. Clean front with BP/W type harness, but the back mounted counter lungs breathe fine (I'm only certified on this one, but have done test dives on the Optima, the Revo and the Inspiration).

Like everything, each unit involves a set of compromises and design choices. But things like service and training options would probably have a big impact on your choice.

 

[rjack321]

Megalodon and JJs are widely available and popular. Also kiss classic is "old" but basically timeless.

 

[wetb4igetinthewater]

Consider the limitations that some rebreathers have that others don't, such as how much gas can it provide you? One of my dive buddies is on a rebreather, and he can't push himself that hard. He also has to ascend/descend slowly. My understand (and I am not a rebreather yet), is that the Meg doesn't have such limitations. I do not know of other rebreathers that perform similarly, but that doesn't mean they don't exist. I just haven't done enough research to know.

 

[doctormike]

Consider the limitations that some rebreathers have that others don't, such as how much gas can it provide you? One of my dive buddies is on a rebreather, and he can't push himself that hard. He also has to ascend/descend slowly. My understand (and I am not a rebreather yet), is that the Meg doesn't have such limitations. I do not know of other rebreathers that perform similarly, but that doesn't mean they don't exist. I just haven't done enough research to know.

Rapid ascents and descents are avoided on CCR to prevent hyperoxic spikes or hypoxia on ascent, even on a Meg. Also, overbreathing can result in CO2 breakthrough and hypercapnia (CO2 buildup) if you are moving gas faster than the scrubber can clean it.

Each rebreather has a certain work of breathing, which is usually available both as resistive WOB and hydrodynamic WOB. The Meg has a great reputation, but its a CCR just like all the others, and physics and physiology isn't something that can be changed by design. Also, different units have different breathing characteristics in different orientations.

 

[wetb4igetinthewater]

Rapid ascents and descents are avoided on CCR to prevent hyperoxic spikes or hypoxia on ascent, even on a Meg. Also, overbreathing can result in CO2 breakthrough and hypercapnia (CO2 buildup) if you are moving gas faster than the scrubber can clean it.

Each rebreather has a certain work of breathing, which is usually available both as resistive WOB and hydrodynamic WOB. The Meg has a great reputation, but its a CCR just like all the others, and physics and physiology isn't something that can be changed by design. Also, different units have different breathing characteristics in different orientations.

I understand that. I asked questions about such limitations to Leon Scamahorn when he presented at a local dive club. Note, I am not a rebreather diver/owner. Ultimately, there are always limitations due to physics and engineering. Engineering/design sometimes makes a noticeable difference.