Question CCR for recreational depths

[CT-Rich]

As I see it, among the "recreational divers/hobbyists" would be "Joe," who finished OW last week, and is debating whether to spit in his mask before diving Molasses Reef in FL.

And then there's "Bill," who's doing trimix gas planning for a rebreather dive — photogrammetry on a wreck at 110m, using a DPV to keep exertion/WOB reasonable.

Neither is getting paid; both can be called "hobbyists" — but these are different dives, and different kinds of divers.

I'm not sure exactly how it plays out with vocabulary, but we're talking about a non-trivial distinction here.

A valid point, but what about “Mary” that is a Photographer and likes to stake out critters with her Camera and get up close and personal? The bubble free and adjustable PO2 may make her interested in long dives at recreational depths.

“Joe” in a couple of years may realize he likes his two tank weekend dives but loves the idea of making it a single four hour dive. He’s seen Mary and Bill at the dive shop and has gear envy. He has money, time and experience. He doesn’t need it, but the cost has come down, the training is available, Why not?

One of my favorite dive sites has a 15 minute surface swim, another 15-minutes on the bottom to get to the interesting parts and you get around 20 minutes to explore the interesting part before heading back in. There are places that are just too far to go on a single tank. The depth is only around 40-50’. Gas limitations are always the controlling factor, not deco.

The future of the rebreather is lower cost, higher reliability, ease of use and ease of maintenance. All the technological changes in diving have come with additional training, additional costs. In the 1950s, your tank came with a manual, most people read the booklet and hardly any of them died…

Some Dive computers cost more than than the combined cost of all other gear. Why do people pay for them? The extra cost gives them extra utility. To take advantage of that extra utility, you need extra training. Almost everyone gets nitrox certified these days, most don’t really need it. I only dive nitrox on vacation. Most people have only a rudimentary understanding of nitrox, but with a the ability of setting a computer correctly, they don’t need more than that.

 

[kimh]

"A valid point, but what about “Mary” that is a Photographer and likes to stake out critters with her Camera and get up close and personal?"

You misunderstood my point. I actually posted earlier about a trend towards CCR for recreational diving, as the tech advances, eventually reaching "Jarvis"-level friendliness — and it's my plan to do rec CCR myself (with current tech). So you'll need to add "Kim" to your example CCR rec divers.

"…unless you are being paid to use a rebreather as part of your work, you are a recreational diver. the term "technical" versus "Recreational" is semantics. the terms denote different styles of diving and training, but are both basically hobbyists."

My problem was with putting the entire spectrum of non-paid divers into one category ("recreational diver"/"basically hobbyists").

I just think that "Mary" the photographer — and my future CCR rec-diving self — will be doing something qualitatively different from the 340' tri-mix CCR, wreck research diver. Even though he's not being paid.

That diver is already doing things that literally would have been the subject of a PBS feature in decades past. And genuine risk is still involved. As I said earlier, I don't know what to do about the vocabulary, but it seems like some kind of distinction would be useful.

 

[Wibble]

Wondering if a trip back to basics might help.

Why dive CCR and what are the benefits?

I guess these need splitting into the "how much skill's required" categorisation. Shall we say "expert" (being a technical diver with much training, understanding and practice) and "novice" (being someone with basic skills and training well within the AOW limits)

"As anyone diving a rebreather, I love"

• The silence
• Not scaring fauna away
• Warm, moist air with no worries about breathing heavily (v. OC)

"As an expert diving a rebreather, I love"

• The flexibility CCR brings where it can be used at different depths with little difficulty, e.g. change the diluent and bailouts and you can dive deep, shallow and everything in between
• The absence of gas restrictions, duration only being limited by OC bailout
• The stability in the water column (hmm: get that from OC as well)
• How light the kit is (compared with OC)
• Cheap diving with Helium+Oxygen (compared with OC)

What's missed from these lists?

 

[berndo]

What's missed from these lists?

All the downsides.

Also, the kit is not lighter than OC unless you don't bring enough BO.

The depth is only around 40-50’. Gas limitations are always the controlling factor, not deco.

As I said before, you could just use doubles or even add a stage. With a rebreather you still need to bring BO.
If you're actually interested in rebreather diving you could just get a used dolphin or older KISS unit for pretty cheap and get training now.
Not need to wait for a magic self cleaning, self disinfecting, self sorb renewing, non-O2 needing, infallible O2 monitoring, super cheap rebreather.

 

[scubaozy]

I think biggest contra is cost per dive and it is not that trivial to fly with it. If you can dive 20 weekends per year and you are driving to the dive spots, I think ccr makes sense. Ah, there is also that it might try to kill you ;-)

 

[Wibble]

All the downsides.

Also, the kit is not lighter than OC unless you don't bring enough BO.

I said… “ Why dive CCR and what are the benefits?”

Care to clarify that?

An open circuit twinset is considerably heavier (65kg+) than a rebreather (~45kg) +10kg bailout.

Or a deeper dive, say 60m/200ft, requires two ali80s on both systems, so OC is still 20kg more.

Or how about not carrying twinsets around for refills— CCR uses 3 litre tins and you can easily get two or more dives from one fill. 100kg extra needed for two days of diving on OC


Not that you'd care, but in my experience, doing a couple or three days of deeper diving is basically not possible on open circuit unless you can bring along full replacement equipment or arrange for overnight fills. I did bring two twinsets and 5 ali80s to do two days diving around 55m. Carrying that lot to the boat was a killer.

On CCR it's so much lighter. Two ali80s for bailout which won't be touched except for test breaths. The 3 litre cylinders (and 2 litre drysuit inflate) will easily last two deep dives. If you were to change scrubber then a couple or three kilos of Sofnolime is all you need.

CCR IS LIGHTER THAN OC ESPECIALLY AS AN "EXPERT" DIVER.

 

[Jcp2]

All the downsides.

Also, the kit is not lighter than OC unless you don't bring enough BO.


As I said before, you could just use doubles or even add a stage. With a rebreather you still need to bring BO.
If you're actually interested in rebreather diving you could just get a used dolphin or older KISS unit for pretty cheap and get training now.
Not need to wait for a magic self cleaning, self disinfecting, self sorb renewing, non-O2 needing, infallible O2 monitoring, super cheap rebreather.

What is the bailout needed for a 50’ open water dive?

 

[berndo]

An open circuit twinset is considerably heavier (65kg+)

I'm getting a headache from your nonsens. A double 12l, which is the standard set is nowhere near 65 kg.

What is the bailout needed for a 50’ open water dive?

Nevermind, just go without.

 

[Wibble]

I'm getting a headache for your nonsens. A double 12l, which is the standard set is nowhere near 65 kg.

Weight of tins, bands+valves; regs; backplate; weights; harness; drysuit inflate + reg; torch+heater batteries... circa 65kg.

Same on a CCR is 45kg.

What is the bailout needed for a 50’ open water dive?

Nevermind, just go without.

That's dangerous, stupid and against all best practices.

Do you actually dive when you're not trolling?

 

[berndo]

I guess I'm not in on the joke. Wibble can't be for real.

If someone actually wonders. One 12l standard euro tank is about 30 lbs/14 kg plus valves, BP/wing etc.
A 12l set of doubles is not 45 lbs/20 kg heavier than a rebreather.

I'm out, don't wanna deal with this nonsense anymore. If y'all wanna believe in some comic book future fantasy tech, have at it.