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KentB

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I used to dive with a cloth in the top, then stopped after I was told rEvo HQ says "no cloth in the top". Only just went back to it this past week.

I have never found my cloth out of position at all. I'm not worried about it affecting the ADV. For that matter, I generally try to dive without ever activating the ADV - and usually succeed. If the ADV somehow stopped working during a dive, I think would find a way to survive. :)
I also dive with a cloth in the top. Not once has it moved or interfered with the ADV.
 

_Ralph

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Did the same on my Meg in the pool on day 1
Couldnt do anything remotely like this on a kiss

*Note ... no experience with any other KISS rebreather*

Did it twice on my sidekick course ... first time it wasn't planned ... apparently I didn't fully close my DSV before I took it out of my mouth doing 'bailout scenarios' .... and when I put it back in, I couldn't get a breath back into the loop .... it was at the end of the dive, so we turned it into a bailout ascent practice.

Next dive was the actual "flood your loop and fix it" dive ...

Wasn't hard (once I knew what/how to do it), and when I did the same on a JJ course, it was slightly simpler (maybe because I have already done it on my sidekick before?)... but I couldn't manage to get all the water out of the JJ loop (gurgling), unlike the sidekick loop.


_R
 

rjack321

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*Note ... no experience with any other KISS rebreather*

Did it twice on my sidekick course ... first time it wasn't planned ... apparently I didn't fully close my DSV before I took it out of my mouth doing 'bailout scenarios' .... and when I put it back in, I couldn't get a breath back into the loop .... it was at the end of the dive, so we turned it into a bailout ascent practice.

Next dive was the actual "flood your loop and fix it" dive ...

Wasn't hard (once I knew what/how to do it), and when I did the same on a JJ course, it was slightly simpler (maybe because I have already done it on my sidekick before?)... but I couldn't manage to get all the water out of the JJ loop (gurgling), unlike the sidekick loop.


_R
you wont get away with this on a sidewinder, spirit, or a classic
 

cathal

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I also dive with a cloth in the top. Not once has it moved or interfered with the ADV.

My understanding on this point is that Paul, advises that a cloth in the exhale loop after it has absorbed any lung butter or water, will expand and weigh heavier and will therefore press down on the inhale lung beneath it and affect the WOB.
 

Whitrzac

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you wont get away with this on a sidewinder, spirit, or a classic
There's a few seconds to fix your ****up on the classic before it floods.lol

2 things that haven't been mentioned.
Most people I know have or had more than 1 rebreather, pick an instructor thats local and actually dives the unit your training on. There's a few around here that have to drive 12+hrs away because there's no one local to teach higher level courses.

Get something with local parts support/community. Overnighting parts from japan is expensive, on top of missing a day of diving. Borrowing a spare from a buddy is preferred.
 

andrespp

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Nope. It's very easy to actually get a hypoxic mix on an mCCR. All it takes is 90 seconds of inattention after 12 years of experience to make it happen.


Have been diving a Kiss Classic since 14 years ago. Even with a clogged orifice, I do not think that going from 1.3 to under 0.2 would happen in 90 seconds, but waaaaaaaaaaaay more time.
 

tbone1004

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I'm with the guys on doing OC for first half and CCR second half. My recommendation is NAUI Cave 1 which at least makes you a "real" cave diver with thirds and a couple navigation decisions, then finish the CCR Cave course.

My argument is worded a bit differently than some others though and is from my course with Tedward and the type of diving that I do. One of the arguments that I have for doing it on OC is that you are highly unlikely to come back for further training if you do a 02H course on CCR. That's an issue to me since you are likely to be heavily task loaded learning to actually cave dive and aren't going to be able to spend much time learning the nuances of actually diving a CCR in a cave, bailuent, SCR, cascading failures, etc. because you are still task loaded by the cave itself.
Having the initial background in OC also allows you to dive if your rebreather decides it doesn't want to dive that day. "Oh well, I have an OC kit in the truck so I'll just dive OC today". Not something you really should be doing if you've never actually done an OC cave dive.
A lot of caves and passages really just aren't suited for CCR. Sure we can get anywhere on a sidemount unit that you can on OC, but if you are diving a Revo, you are restricted in where you can go with some restrictions, or in some shallow caves that are backmountable but are depth rollercoasters, the CCR is a righteous PITA. Sometimes you just want to do a 60-90 minute cave dive which is hardly worth the hassle of a CCR IMO and OC is just easier. I would much rather just throw on a set of doubles to do the crossover circuit in Peacock than take one of my CCR's in there. I have done it, but it's a lot of extra work for a really short dive. That gives you the added advantage of keeping your SAC rate in check which a lot of CCR divers like to think that they still have a 0.4-0.5 SAC rate but after a year of not diving OC it's more like 0.8-0.9 and it's a rude awakening in their bailout calculations. It doesn't excuse practicing bailing out, SCR, etc. but in high flow caves it gives you a much better appreciation for the CCR.
 

tbone1004

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Have been diving a Kiss Classic since 14 years ago. Even with a clogged orifice, I do not think that going from 1.3 to under 0.2 would happen in 90 seconds, but waaaaaaaaaaaay more time.

90 seconds is probably a bit exaggerated but if you are running min loop volume and are relatively shallow it won't take terribly long. For easy numbers let's assume a tidal volume of 1L plus about 3L of "dead space" inside the unit for the loop hoses, canister, and head. 4l of volume at 4ata=16L at surface. You shouldn't run a 1.3 ppO2, but whatever, 1.3/4=32.5%. 16*.325=5.2L of O2 inside of the loop at 1.3. 0.2/4=0.05L *You can't actually do this without adding Dil because you'll collapse the lungs which is why min loop is so important, but we'll roll with it*, so you consumed 5.2L-0.05L=4.7L of O2 consumed. Assuming the "rule of thumb" of 1lpm, that is just under 5 minutes to go from 1.3 to 0.2 at 100ft. If you were at 30ft, it would be right around 2 minutes, and about a minute at the surface. Obviously the opposite as you go deeper since there is more mass of O2 in the loop. More if you don't run at min loop, more if you have a dil that is matched to your ideal bottom ppO2, etc etc. but I'm not sure that I would consider 5 minutes "WAAAAAAAAAAAAAAY" more time than 90 seconds.

to reiterate the importance of minloop volume though. To drop from 1.3 to 0.2 you would need to consume 4.7L of O2 from the loop at the surface when normalized for depth which correlates to ~1.2L at depth. If you look back at the math above, we used 1L for the tital volume calculation. Since we consumed more O2 than we have accounted for in tidal volume, you would have to create a vacuum in the rebreather which you obviously can't do. Your body would tell you "hey dipsh!t, I can't breathe anymore, you need to add gas into the loop" and at that point you would check your ppO2 and see that it had dropped and you needed to replenish that lost volume with O2 instead of dil. If you are maintaining minloop volume AND you are not changing depth, you don't need a ppO2 display to maintain a constant ppO2. Maintain minloop volume and you will inherently maintain a constant ppO2. Hypoxia should never be a concern on a CCR when diving with proper loop volumes unless you are ascending.
 

andrespp

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90 seconds is probably a bit exaggerated but if you are running min loop volume and are relatively shallow it won't take terribly long. For easy numbers let's assume a tidal volume of 1L plus about 3L of "dead space" inside the unit for the loop hoses, canister, and head. 4l of volume at 4ata=16L at surface. You shouldn't run a 1.3 ppO2, but whatever, 1.3/4=32.5%. 16*.325=5.2L of O2 inside of the loop at 1.3. 0.2/4=0.05L *You can't actually do this without adding Dil because you'll collapse the lungs which is why min loop is so important, but we'll roll with it*, so you consumed 5.2L-0.05L=4.7L of O2 consumed. Assuming the "rule of thumb" of 1lpm, that is just under 5 minutes to go from 1.3 to 0.2 at 100ft. If you were at 30ft, it would be right around 2 minutes, and about a minute at the surface. Obviously the opposite as you go deeper since there is more mass of O2 in the loop. More if you don't run at min loop, more if you have a dil that is matched to your ideal bottom ppO2, etc etc. but I'm not sure that I would consider 5 minutes "WAAAAAAAAAAAAAAY" more time than 90 seconds.

First, you are ignoring the fact that some oxygen will be introduced along with the DIL. The amount of course, will depend on how hypoxic the DIL is. Second, when it comes to live or dead situations, going from a safety margin from 90 second to 5+ minutes is a whole world of a diference.
 

AJ

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That's an issue to me since you are likely to be heavily task loaded learning to actually cave dive and aren't going to be able to spend much time learning the nuances of actually diving a CCR in a cave, bailuent, SCR, cascading failures, etc. because you are still task loaded by the cave itself.
I have a question on this. What if you're an well educated (mod 2 or 3) accomplished diver (lot's of hours) on a CCR. Will this argument still hold in your opinion? I understand learning to dive a CCR and doing Cave is not wise and you should be an accomplished OC diver to be able to bailout safely.

Just curious what's your opinion on this.
 
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