Question CCR for recreational depths

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I think Id rather have the Fathom than a Choptima. Choptima puts all the steel on my back, and floaty stuff on my chest. I think Id rather have it the other way around. Floaty rebreather on my back, tanks slung (if needed).
I certainly would like to have a go on a Fathom too. They sound well thought out, analogue and less prone to breakdown. However I don't know if they have made it to Western Australia (WA) yet. WA stands for wait a while
 
Since I know the designer and builder of the RD1 Oxygen Rebreather, Mike Lombardi I figure I will pipe in to share what I know about both the designer and the rebreather since I own one myself.

Mike Lombardi is a commercial diver, scientist, engineer and inventor. Mostly self-taught I am pretty sure, and he should correct me if I am wrong on that point. He is fully invested in getting people to appreciate and explore our oceans much like Elon Musk is fully invested in colonizing Mars. I found out about him on a project he was doing in the Bahamas with National Geographic and he along with his partner on that project (a frequent dive buddy) have been very instrumental in getting me back into diving and rebreather diving especially. He has an organization to focus on his research and outreach which can be found here:

His other organization is all about designing, building and manufacturing diving equipment for use in the commercial and scientific/ research industries which can be found here:

During Covid he also used diving technology to help design an Oxygen hood that could help Covid patients avoid respirators but unfortunately the U.S. was slow to adopt the technology due to the many regulation hurdles, but it had a lot of success overseas.

Mike has been a rebreather diver since the early 90s and is certified on a few of the mainstream rebreathers of today. He has built a few rebreathers for himself. He feels very strongly, as do I, that most rebreathers sold today are more expensive than they need to be. We all do not need Hummers and Maseratis to pick up milk down the street. This coming from myself, a Poseidon owner (the Mercedes of rebreathers) The idea for the RD1 Oxygen rebreather came about during his time harvesting shellfish. The idea was to build a rebreather that could be light, durable, and easy enough to work out of small boats or off the shore especially when you are dragging bags and baskets of shellfish. Hence the backmount design and light weight. Also, there is thought put into it being used in a commercial environment.

One of the difficulties of learning to dive a rebreather properly is learning to control the buoyancy. By starting with an O2 rebreather the student can learn in a shallow environment (the most difficult place to learn) without worrying about managing their PO2. This where the rebreather gets its name Rebreather Day 1. Technically it takes more like a day and one half. The student learns how to set up the rebreather which takes about a half a day. But then is brought to a protected shallow training site to practice the skills and make some long dives in one day.

The rebreather can be purchased in two ways:
1. As a kit to current certified rebreather divers. If a certified rebreather dive cannot figure out how to put it together, they probably should not be diving it any way or their own rebreather for that matter. This is, from what I understand, how the KISS rebreather was originally offered. That is what is available on his website.
2. As a training package. The student gets the full setup ready to dive, manual and training as a package price. He is not advertising a price on his website but I think the current rate is around $3500-$4000.

As a certified MK-16, Lar 5, Inspiration and Poseidon diver it is the lightest unit I have ever dove. It is also dirt simple to build and prep. It is also very easy to modify to an Mccr and Mike has designed and manufactured the pieces to do just that. Although he tends to favor a needle valve vs CMF. A mixed gas training path has been developed but he is currently in the process of getting recognized by an agency.
 
So this is a curiosity question. I had the chance to use a R1 O2 rebreather the other day in a try it dive at local pool. It was a pretty cool experience and it prompted a question. Would one of these rebreathers be able to replace my conventional OC scuba for diving at recreational depths?

Here is my situation. I typically dive with a steel 120 and most if not all my diving is above 100'. I am getting older and father time is catching up with my back. at some point I will no longer be able to sling all the lead and steel. The CCR is much lighter than a traditional OC system.

I understand that because of the PPO of a pure O2 diving is limited to 20' and repeated prolonged O2 can have an effect on your lungs. But I heard from the guy doing the try it dive that the rigs can be modified to use air as a diliuant and work at greater depths.

My question is would this be a viable option? With a upgraded DR1 would it be a viable way to dive within recreational limits? With a system like this would it a kin to breathing Nitrox at a fixed ratio or would it would the gas blend be adjustable like used in other CCRs? This is mostly an academic exercise, but I would not mind being able to go out on my usual underwater bumbles, which normally range from 30-60 FSW without having tank pressure as my limiting factor.
CT-Rich for the type of diving you do with the right size tanks you could easily hang out in the 30-60 FSW range for approx 3 hours as that is what the scrubber is currently rated for. The current tanks you used during your try dive would be a little too small for diving to 60 feet. There is enough O2 just not enough diluent for a safe controlled bailout from 60 feet but some short 19 cuft tanks should work just fine.

As far as weight I will have to check but you will not be saving a whole lot of weight off your back unless you sidemount/sling the bailout which would allow you to suit up at the shoreline or right off a boat and then hand the bailout up before getting back onboard. You could one or multiple dives at those depths with no tank change outs in between. Just a total of approx 3 hours of bottom time. Just need to make sure you are wthin NDL limits.

One of the biggest things I enjoy about rebreather diving is how close I get to sealife. I have had some pretty cool encounters on a rebreather and have seen what happens when the noisy open circuit divers show up during my encounters.
 
I don't think those words mean what you think they mean. You're a single first stage failure away from unrecoverable issues.

I don't see how a breather with a single dilout tank is any less redundancy then a single tank alone.
 
No, but it is considered by many to be sufficiently reliable for open water rec dives, which this thread is a about. It is the industry standard standard for rec dives.

Exactly. If the OP is comfortable doing the dive on a single 120, I see no problem with them doing the same dive on a single dilout tank.
 
@CT-Rich,

A couple of people suggested above that baby doubles might be the answer for you. However, keep in mind that my empty LP50's together are approximately the same weight as my empty HP120 (Sherwood Genesis 3,500 psig cylinder)--about 40 lbs. So, a bit heavier if you include cylinder bands and bolts and the middle valve part of the manifold.

Moreover, these double LP50's are not as negatively buoyant as my HP120--so, more weight is required on your weight belt, maybe.

The LP50's do dive a bit better (for me) and, being shorter cylinders (25" vs 28"), are easier to carry by the valve.

FWIW.

rx7diver

P.S. Diving a DH regulator on baby doubles (using a solid-bar, single outlet, J-valve manifold) is delightful and will route your exhaust bubbles behind your head, away from your face and ears. So, there's that...
 
By the time you add bailout and lead to sink the CCR (most being somewhat buoyant) you are not going to be lighter than a single tank. The 120 is about the heaviest tank there is (short of a heiser 149 beast). As we age and gear gets heavier and heavier I would recommend: 1) switching to a smaller tank like a hp100 or even an hp80 and just doing shorter dives. 2) switch to warmer water with less lead and exposure protection diving.
 
Is that why we're seeing 4 tank backmounted setups?

Looked like two lp50, one fx23 for oxygen, one fx23 for suit inflation.

If you need to add weight, it minus well be partially breathable?

Im not concerned about the weight of the bailout, or some of the weight on my belt. I can drag that, pass it, put it on in the water. Lifting a rig onto my shoulder might be the 2nd worst thing about this sport. Im not in the "put weight on the bpw, not the belt" camp. Because then it gets harder to lift.
 

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