CCR Selection priorities

[Jack Hammer]

Cool PDF. I guess you weren’t able to track down the actual video of the testing conducted to “prove” the point as expert witness testimony. No worries, I’ve got it right here for those in the audience who are unaware of the type of testing conducted by “deep life” and “open safety”.

Now that's some high quality lab work.

 

[rjack321]

Now that's some high quality lab work.

$160k worth as i recall
That's what this shameless suite cost the estate in legal fees

 

[flymolo]

What are those videos supposed to demonstrate?

 

[NothingClever]

What are those videos supposed to demonstrate?

I think in the first video it’s supposed to reflect what life is like as a potato chip in a bag.

 

[flymolo]

I think in the first video it’s supposed to reflect what life is like as a potato chip in a bag.

Haha that was pretty good

 

[Jack Hammer]

What are those videos supposed to demonstrate?

I think they quite clearly demonstrate that no matter how much we advance there is still a sucker born every day.

 

[stuartv]

1. Flood tolerance/recovery: For the types of dives rebreathers are intended for (long, deep, extended range dives), flood tolerance is a critical design attribute that must be considered. Several hours away from the surface is not a place to be regretting the fact that your loop is flooded, scrubber is soaked, and your only option is bailing out. Be aware of the loop design to make sure there are sufficient water traps between the exhale side of the mouthpiece and the scrubber. You drool into the loop, and your moist exhaled gas condenses inside the loop hoses. If the scrubber is directly in line with the exhale side of the mouthpiece, that means it is actually functioning as the water trap. This can significantly affect the work of breathing, scrubber efficiency, and increases the risk of a caustic cocktail.

That's about it for now. Discuss

I'm a bit unclear on what you intend for people to discuss. Are we supposed to discuss what we think of the priorities you described? Or are we supposed to discus how we think different units that are available meet your priorities?

I do think that your point about Flood Tolerance/Recovery seems, I'm not sure how to say this, short-sighted? Not addressing the full picture? I mean, it seems like it would prioritize a unit that is easier to get water out of, over a unit that is harder to get water out of. But, it fails to give any consideration to how easy or hard it is for a unit to get water in it in the first place.

If Unit A is easy to get water out of, but it actually gets water in it a lot, because of other design factors, should it really be prioritized higher than a unit that is very difficult (or impossible) to get water out of, but is designed in such a way that is basically never gets water in it (barring the user taking the DSV out of their mouth while it's open)?

You have some important factors listed above and many rebreathers have pros and cons. Using the number above, could you maybe list out a top 2 or 3 units and "bottom" 2 or 3 for units for each. An example, I am no expert, but revos and Optimas seemed to be a little more complicated to set up vs JJ/Meg. Revos are known to have very poor flood tolerance, which unit has some of the best, why?

I don't have any significant experience with other units, but the rEvo does not seem to me like a unit that would be considered complicated to setup. I was diving my rEvo alongside a buddy on his Tiburon (a Meg with Shearwater electronics, as far as I know) this past weekend. We dived Saturday and then had our units back at our room after to "refresh" for the next dive. Mine seemed much quicker and easier to break down and clean, but we were doing other/different things at the same time, so maybe that was not a fair comparison. But, the next morning, we both had to reassemble them and go through our respective Closed/Build checklists before heading to our boat. My rEvo was together and the Closed checklist done in 5 minutes. We started at the same time and he was another 5 to 10 minutes after I was done before his Tiburon was ready to go. We actually compared checklists side by side. His had 37 steps (if I recall what he told me correctly). The rEvo Closed checklist has 18 steps. Not counting steps for checking BO. Looking at the two checklists, the rEvo checklist sure looked WAY simpler.

"Poor flood tolerance" is a funny way to describe a rEvo. It has NO flood tolerance. Once water is in there, there is no way to get it out (during the dive). But, there are only two nuts to put on and tighten, if using the stock DSV, and the scubber cover to put on to seal it up. I don't really know other units, so please don't take this as me making a definitive assertion that the rEvo is better than any other unit. But, one of the things my rEvo instructor mentioned during training is that the very few places for a rEvo to leak makes it, not flood-tolerant, but (my words) highly flood-resistant. My rEvo instructor also teaches several other CCRs, so I didn't take that as pure rEvo Fandom speaking. I've read (here on SB) where one person knocks rEvos because they had the rEvo counter lung OPV come apart during a dive, and the unit (of course) flooded. Other than that one report of that one incident, I have not read of another rEvo flooding (unless the diver took the loop out of their mouth underwater without closing it first).

So, maybe the rEvo Zero Flood Tolerance is somewhat mitigated by a design that makes it less likely than other units to flood in the first place?

Again, I'm not trying to making assertions about this. I am new to CCR diving and really only have rEvo experience. I'm putting this out there so someone more knowledgeable can give the counterpoint.

 

[kensuf]

While I agree the best option is to not flood the unit to begin with, the reality is any unit will flood under the right circumstances. It could be something as simple as loose lips, or something that's more insidious like a torn mouthpiece ("hey this unit passed a positive and negative but I still get water in it!").

I got a fair amount of water in a KISS Classic once when I was ~3 hours away from the surface. That wasn't a particularly fun day.

 

[hroark2112]

I went through this whole “unit passes a positive and negative test all day but I get water in the loop” issue not long after I got into diving a CCR.

Lesson learned - Seacure mouthpieces don’t seal well on a large BOV opening!! For some reason I despise the standard mouthpiece on nearly every regulator and BOV I’ve ever had. Coming from a sports background where a mouth guard is a smart idea, the moldable units seemed like a great idea. Turned out to be a BAD idea!!

 

[stuartv]

While I agree the best option is to not flood the unit to begin with, the reality is any unit will flood under the right circumstances. It could be something as simple as loose lips, or something that's more insidious like a torn mouthpiece ("hey this unit passed a positive and negative but I still get water in it!").

I got a fair amount of water in a KISS Classic once when I was ~3 hours away from the surface. That wasn't a particularly fun day.

Understood. No question there.

I guess maybe the way I should have expressed what I said is that, when you evaluate a given unit for its "flood"-related characteristics, should the evaluation only look at how well and easily you can dewater? Or shouldn't it also look at how resistant the design is to getting flooded in the first place?

It seems like both those aspects of a unit should be looked at - not just the one.