Where should I start to approach the rebreather world

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stuartv

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Unless the unit is a fully manual Revo, in which the monitoring systems are both fully independent and fully redundant, nothing else is redundant from an engineering perspective. That is not up for debate, it is a fact. If you believe the scrubbers are redundant, shame on your instructor for misleading you and if you have an electronic Revo and think the electronics are redundant, shame on your instructor for misleading you because they are not.

God is not a good analogy because it is not something we can prove. What you are saying is that you perceive the earth as being flat therefor you believe the earth is flat. Unfortunately the earth is not actually flat, ergo you are not entitled to that opinion because it is a fact.

A rEvo with a Petrel/Predator handset, and a NERD, and 5 (or 6) O2 sensors has fully independent, fully redundant ppO2 monitoring.

That is the same whether there is a solenoid in the unit or not.

Can any other unit on the market make the same claim? Maybe the Liberty - sort of - because the Liberty does not have 3 cells on either "side" to afford the safety of Voting Logic (which, apparently, EVERYONE else except Poseidon agrees is a good idea).

Look, if you gave me a Revo and said you have to use it as your primary backmount unit, I wouldn't complain. I wouldn't use it in its stock configuration because I think 5-cells is ludicrous, and I would bitch about it because it won't dive in flat trim in a wetsuit,

Have you dived a rEvo? What is your basis for saying it won't dive in a wetsuit in flat trim? I have no trouble staying in flat trim with my rEvo, in a drysuit or a wetsuit or board shorts and a rash guard. With no lead at all.

In a wetsuit:
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tbone1004

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@stuartv I did say that the monitoring side is redundant, but the control side is not and that's an important distinction because failed 3-cell voting logic can wreak havoc on the system and there is no check against that, and as pointed out earlier, people have died because of it. You can't stop that from happening with any unit on the market with a solenoid except Liberty and Se7en.

Yes I have dove the Revo, yes in wetsuit, no it did not want to trim out. IIRC yours is Micro Titanium yes? I was diving a full size one at the time but I have heard form many full time Revo divers that with the full size units they don't behave well in wetsuits and are really foot heavy and with sidemounted bailouts are not divable in a wetsuit.
 

stuartv

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@stuartv I did say that the monitoring side is redundant, but the control side is not and that's an important distinction because failed 3-cell voting logic can wreak havoc on the system and there is no check against that, and as pointed out earlier, people have died because of it. You can't stop that from happening with any unit on the market with a solenoid except Liberty and Se7en.

Yes I have dove the Revo, yes in wetsuit, no it did not want to trim out. IIRC yours is Micro Titanium yes? I was diving a full size one at the time but I have heard form many full time Revo divers that with the full size units they don't behave well in wetsuits and are really foot heavy and with sidemounted bailouts are not divable in a wetsuit.

The fully redundant monitoring system is the "check" against what can kill you in a 3-cell unit.

I feel like there is some real waffling going on about this. Either, 3 cells can kill you because of voting logic and 2 bad cells, and that is a big deal - in which case 3 cells is clearly not as good as more cells with independent monitoring. Or, 3 cells can kill you because of voting logic and 2 bad cells, but it's not a big deal because, one, it is SO unlikely to happen, and, two, if you do have the 2 bad cells and voting logic that WOULD kill you, it's so easy to see it starting to happen, verify that you only have 1 good cell, and still get yourself out safely. In that scenario, it may be no big deal (to you), but I'd still rather have the 1 good cell plus 2 more good cells on my independent monitor to look at as I'm finishing my dive.

Personally, if I only had 3 cells total, and I knew that 2 of them had gone bad and I now have just 1 to monitor as I fly my unit manually through my exit and all my deco, my butt would be seriously puckered the whole way. I would have the constant nag, "how do I KNOW my 1 sensor is still good and accurate?" Can't be doing constant dil flushes the whole way out. You'd run out of dil, plus once you get away from the bottom, the dil flush isn't going to verify the sensor is working at the ppO2 level you're flying at. You could do flushes with offboard as you get to the right depths, to spike the ppO2 to a known safe level, to verify the sensor that way. But, I'd still be flying ;puckered and wondering if the 1 cell was crapping out at any moment. I mean, you know, 2 cells crapped out. Maybe something is going on in the unit and the 3rd one is about to get taken out by whatever took out the first 2. Maybe that would just be paranoia. Regardless, having an independent monitor system that lets me continually verify that 1 "good" cell still really is "good" would be very much of a relief - to me.

Yes, I have a Micro Titanium. I had a Mini Steel before that. My Micro has a somewhat heavy rEvo factory stainless stand on it. The Mini had a lighter Don Six stand on it. Both of them trimmed out just fine for me in any exposure protection.

The pictures above are older. Now that I think of it, I think those are all me in my old Mini.

Since my last training, in July, I swim my Micro with all my BO/deco attached sidemount style. Whether it's a single 40 or 3 x AL80, all slung SM-style, it still trims out the same for me.

I will note that my wing is a Dive Rite Nomad XT - not the default rEvo wing. I attribute some of the "easy" trim to that wing, as it is shaped to give more lift down low, compared to most wings. I had the Nomad on my Mini and moved it over to my Micro when I got that.

I dived yesterday with my friend who has my old Mini. It's got an Agir wing on it now. He seemed to have solid, flat trim - with no lead anywhere. But, he was in a drysuit and basically no undergarments.

You'll probably take that as justification for your early statements, because I'm not diving with the "intended" wing. Suit yourself (LOL!) on that. I think most CCRs have a wing you can buy with it, but are free to use any other standard wing that you want. Yay for rEvo for not locking you into using "their" wing and supporting use of any standard wing. I reckon if you use the wrong wing on any CCR, you can make it have bad trim.
 

Wibble

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I will note that my wing is a Dive Rite Nomad XT - not the default rEvo wing. I attribute some of the "easy" trim to that wing, as it is shaped to give more lift down low, compared to most wings. I had the Nomad on my Mini and moved it over to my Micro when I got that.

I dived yesterday with my friend who has my old Mini. It's got an Agir wing on it now. He seemed to have solid, flat trim - with no lead anywhere. But, he was in a drysuit and basically no undergarments.

I have no issues with diving in flat trim on my Revo mini -- cold water, drysuit, steel tins + suit inflate, large suit heater battery and Kent Tooling stand. Have an additional 850gms underneath and between 1kg and 2.6kg on the top tray.

No idea about warm water, never seen it -- think you're all having a wind-up.


@stuartv - wings. Could you please post a couple of links to the DiveRite wing you've used and the other person's Agir.

The Revo wing's OK, but a horseshoe. The other "superfabric" one is even bigger.
 

tbone1004

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The wing looks like this and is designed for the sidemount rig that Dive Rite sells and would certainly help with the trim issue though if you sidemounted with steel bottles like we have to in cave diving it wouldn't solve that problem. AL80's usually help the trim problem since they are butt floaty.

@Wibble it trims fine in a drysuit because you will subconsciously put some air in your feet so you trim out properly, can't do that on a wetsuit. It's not a windup, Wyatt has already confirmed that as a Revo instructor teaching in the Keys and in cave country, it's a very real issue with the unit. Most CCR's are foot heavy with the exception of the SF2 and Sidewinder because the counterlungs are up high, but not as bad as it felt in the Revo with that 3mm.

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JonG1

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TBF Wibs Ben has struggled with his trim and is trying all sorts and let's not forget Karol the Silty Seahorse either !
 

Wibble

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TBF Wibs Ben has struggled with his trim and is trying all sorts and let's not forget Karol the Silty Seahorse either !
Was odd to be the 'flat one' out.

Dunno why it's caused so much grief for others. I had to add a 850grm/1.8# weight to the bottom to hold it down, I felt very head heavy prior to that.

A lot of it can be adjusting the placement of cylinders and the like.
 

JonG1

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Was odd to be the 'flat one' out.

Dunno why it's caused so much grief for others. I had to add a 850grm/1.8# weight to the bottom to hold it down, I felt very head heavy prior to that.

A lot of it can be adjusting the placement of cylinders and the like.
Nothing to do with your slightly different COG then.....
 

Wibble

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Nothing to do with your slightly different COG then.....
Please sir, he's calling me a short-arse!
 

macado

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rEvo trim is just horrible..
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Especially in a wetsuit.. it really sucks.
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I'm not sure how I ever survived on a rEvo but I thank the Photoshop rotate/crop function. I think this winter I'm going to start a new Instagram page called "CCR Divers in Horrible Trim at Ginnie Springs" I'm sure I'll have lots of JJ, X-CCR, KISS, Fathom, SF2, Prism2 and rEvo divers in horrible trim. Not RB80 divers though.. :cool:
 
https://www.shearwater.com/products/peregrine/

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