Dive Talk Go Rebreather

[LFMarm]

Let's forget about the specific numbers in terms of hours. Use whatever numbers you want for your rebreather scrubber duration. Why is rule of 1/3 not applicable to CCR scrubber duration?

My philosophy is that you save 1/3 (or more) reserve for the life support consumables needed to exit the cave (gas in OC, lights, DPV, etc.). When diving in CC your reserve for the rebreather unit (which includes your scrubber) is your OC bailout. If you save 1/3 of your scrubber, you are adding conservatism on top of your Plan B (i.e., OC bail out gas).

Adding conservatism is not bad so you should keep doing 1/3 scrubber reserve if that is how you like to plan for contingency. It's just different from what most CCR cave instructors are teaching and hence the questions in this thread. I would never back away from conservatism that I feel necessary because others do more aggressive planning (a personal example are gradient factors as I am usually the most conservative diver of the group but do not go for more aggressive GFs to match the others).

 

[inquis]

It's just different from what most CCR cave instructors are teaching

I'm not so sure. TDI standards are silent on the topic, but NSS-CDS standards state Thirds on the CCR consumables:

At any point during a CCR cave dive, divers must have twice the oxygen, diluent, and absorbent to exit the cave.

Seems overkill to me given the OC reserve, but presumably instructors are teaching to the standards.

 

[LFMarm]

I'm not so sure. TDI standards are silent on the topic, but NSS-CDS standards state Thirds on the CCR consumables:

Seems overkill to me given the OC reserve, but presumably instructors are teaching to the standards.

"Most" is based on my pretty small sample of ~15 CCR cave divers certified with ~5 different instructors.

 

[jale]

Let's forget about the specific numbers in terms of hours. Use whatever numbers you want for your rebreather scrubber duration. Why is rule of 1/3 not applicable to CCR scrubber duration?

Conservatism is never bad but as rjack321 said it is misleading to apply a general rules for scrubber duration.
Is a 4-hour dive in a swallow cave with minimal deco and with no scooter the same as a deep dive with a scooter where you spend most of the time handling at deco?
Too many variables affect the scrubber and each dive has to be planned carefully.
That the reason, I am again a general formula for scrubber duration.

 

[rddvet]

I lost a ton of respect for them over this past year.

The channel used to be awesome, covering legitimate topics like the ones we cover on SB in video format along with their reaction videos.

Now it’s all blatant marketing and clickbait thumbnails. They do not take any kind of criticism well and pander to the most common denominator in their fanbase. You can’t have a serious discussion on their Facebook group, for instance, without people losing their minds. Maybe Scubaboard ain’t that different on that last point.

They also get very preachy about anyone vocalizing criticism and “judging how other people dive”, yet they built their whole said channel on doing just that.

You’re just learning they’re tools?

 

[Zach The Diver]

You’re just learning they’re tools?

More that I saw them as entertaining advocates for diving when I first jumped in a few years ago. I used to really like how they’d find obscure dive footage that warranted some interesting discussions.

Now I see them as the very thing they said they stood against. They should rename themselves because you can’t have a reasonable or coherent “talk” with them or their clan of followers.

Consider that I was new to diving when I found them so my “tool diver radar” hadn’t fully developed yet.

 

[rddvet]

More that I saw them as entertaining advocates for diving when I first jumped in a few years ago. I used to really like how they’d find obscure dive footage that warranted some interesting discussions.

Now I see them as the very thing they said they stood against. They should rename themselves because you can’t have a reasonable or coherent “talk” with them or their clan of followers.

Consider that I was new to diving when I found them so my “tool diver radar” hadn’t fully developed yet.

I was just messing with you.
They fall under the category I call Kave Kardashians. All fluff for internet appearances. Only difference between them and the real Kardashians is they got famous for diving videos not a sex tape.

 

[rddvet]

ty. Most use the rule of 1/3's. This goes for EVERYTHING, not just gas. Battery run time on lights/scooters/heaters are also included in that rule. As should your scrubber duration

Not sure where you're getting most are using 1/3 of scrubber. I can say no one I personally know dives 1/3 of scrubber.

I'm not so sure. TDI standards are silent on the topic, but NSS-CDS standards state Thirds on the CCR consumables:

Seems overkill to me given the OC reserve, but presumably instructors are teaching to the standards.

Is the NSS-CDS teaching 1/3s of scrubber? I hadn't heard that before. But I pretty much ignore the CDS as a training agency nowadays. I'm strongly in the camp the CDS should stop being a training agency and focus on conservation and property management.

 

[Capt Jim Wyatt]

I'm strongly in the camp the CDS should stop being a training agency and focus on conservation and property management.

Why?

 

[Zach The Diver]

Now that’s funny!