Advice Requested - Open Circuit Tech Diving or Rebreather Diving?

Hello ScubaBoad,


Currently, I am PADI Rescue Diver certified and am a proficient, competent diver with extensive experience and wish to take my dive training and diving experience far beyond "vacation" diving (the movie Open Water).


I am at a crossroads between pursuing further instruction for my diving: whether to pursue further training in open circuit technical diving (doubles, backplate & wing… etc.) or to pursue training in rebreather diving (closed or semi-closed).


The basic concepts I am familiar with of both technical open circuit and rebreather diving.


From your experience what are the in-depth pros and cons of open circuit versus rebreather diving? What would your recommendation be? Should I pursue training in both rebreather and open circuit tech diving?


Thanks a lot for your advice!!

What are you actually looking for? Do you want to improve basic diving skills, or are there specific dives you want to do that you require more training to execute? If the latter, I'd say where you go depends on what those dives ARE, and the people with whom you are considering doing them. Do remember that rebreather bailout is to open circuit, so having some experience with open circuit technical diving, deco planning and gas switching may be useful even for the rebreather diver.

The obvious advantage of a rebreather for technical diving is that your helium use is much diminished, making the per-dive cost less. The initial outlay is higher, both for equipment and training, and a rebreather has additional complexity to avoid hyper- or hypoxia, or hypercarbia -- all of which are risks on OC as well, but in some cases to a much lesser degree.

I'm not sure you will get a usable answer here, because people have strong opinions either way. I know and have dived with a number of rebreather divers who are perfectly content and feel it is the only way to dive. I am personally afraid of rebreathers, myself. I think the items in the DAN fatality report a couple of years ago in which two different divers died testing their rebreathers in shallow swimming pools had a detrimental effect on my attitude.

The one piece of advice I can give you is that from what I observed, rebreathers can take a while to master. The buoyancy skills are quite different and take a while to get used to. I know a veteran open circuit cave diver who after 50 rebreather dives said he was not yet ready t take it into a cave. I think the lesson is that if you decide to go with a rebreather, then go with a rebreather--don't dabble in it.

This topic can open a lot of wounds.....
I am currently going up the OC track with the intent of going rebreather. Now that I am 3 years in I am not so sure about my choice. I dive with a lot of re breather on a regular basis, and in talking to them this is what I took away.

The re breather is a tool.
It has an application.
Specifically where the logistics of gas come into play.
As long as the gas logistics do not become an issue, there is no real "need" for a re breather.
If you just "want one" then that is a choice that comes with a lot of baggage.

3 years ago a lot of these guys dove their re breathers all the time even if it was a 80fsw jaunt just to get hours or stay fresh. Last year I noticed a migration back to OC on dives in the 150fsw or less. I asked them about it and the response was it was quicker and easier to dive OC if the gas was not an issue.

It gave me pause, and now I may never get a re breather based on my target depths not being gas prohibitive. YMMV and I am no re breather guy either.
Eric

waterpirate:

3 years ago a lot of these guys dove their re breathers all the time even if it was a 80fsw jaunt just to get hours or stay fresh. Last year I noticed a migration back to OC on dives in the 150fsw or less. I asked them about it and the response was it was quicker and easier to dive OC if the gas was not an issue.

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I really think that is the key thing to think about.

Not long ago I did a dive with a pair of HP 108s on my back while carrying an AL 80 and 2 AL 40s. There was a guy using a rebreather with us. As we headed to the back of the boat to get in, I looked at him and thought, "Hmmmm."

rebreathers are king of the hill for deep diving as the gas use is very small and the accelerated deco is always at the max giving minimal deco.

the deep rb boys still have to carry loads of oc bail which sort of negates any advantages over oc.

when there is a commercially available twin /indy rb then that would be the way to go.

some go alpinest but not many.

2p

Lots of possible advice. I'll throw in a few:

• Open circuit (OC) and rebreather (RB) technical diving is not necessarily inconsistent. One can pursue both.
  
• Both can be highly damaging to your wallet.
• You are much more likely to die if you pursue the RB option. Statistically.
• The deeper you plan to go, the more the advantages of RB will come to the fore.
• RBs are more "all-in". One can transition more slowly to technical diving on OC without the need to "re-learn" certain areas (such as bouyancy control) for RBs.
• Almost anywhere you might want to dive can provide OC and OC support. That is certainly not true of RB support.
  
• I truly believe that RBs are the future. My grandchildren will probably never dive OC. But the future hasn't arrived yet.

lobbolt:

...am a proficient, competent diver with extensive experience...

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If you have the money and the time, you should definitely learn both systems so you can use whatever tool you need for the dive (and team) you are doing. Both have advantages and disadvantages, some of which are hotly debated by persons with far more experience and knowledge than the little people

And if you start technical training and don't reach a point where you take back what you just said, I'd consider a different hobby...

Get really, really good at OC before going to CC. It makes the transition so much easier and, depending on the unit, you may still need a lot of your OC stuff to dive CC.

mala:

the deep rb boys still have to carry loads of oc bail which sort of negates any advantages over oc.

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Having to carry bailout doesn't negate any advantage of RBs. Bottom gas requirements are much greater than bailout requirements. Plus cost-wise you don't have to refill your bailout bottles on most dives.

My view (and I fully expect to get jumped on by the "rebreathers are the best tool for everything" camp, but I'm going to say it anyway), is that rebreathers add risk. They are more complicated systems that can kill you without warning from a single failure.

Offsetting that, they give you more available gas for a given amount of equipment carried on you during a dive. Therefore, as the dives become inherently more and more risky (deeper, or further back into caves), the higher safety margin afforded by the greater supply offsets the higher risk involved in diving a rebreather.

There are practical tradeoffs, but from a risk perspective, that's it: higher per-dive and per-minute-diving risk vs. more gas.

So the question is, what type of dives do you want to be doing, and how often do you want to do them? It's totally possible to do dives to 250 feet regularly on OC. The hassle factor gets pretty high, and in those depth ranges I think the risks of RB start to be balanced out by the benefits.

If all you're ever going to do are 150 foot dives, OC trumps RB from a safety perspective, easily.

And then the question: even if you want a breather, should you train OC first? I'm staying out of that debate