mCCR to eCCR

[Joshua Smith]

Well, after much thought, and much soul-searching, I've come to a decision that will be mostly meaningless to all but a few of you who will read this.

I'm heading down to Portland tomorrow to do some work for a friend of mine. I'm making a pit stop in Centrallia to drop off the head for my Megalodon at the ISC factory- I'm having it converted from COPIS to APECS; or from manual to electronic.

I know full well that some of you are taking mCCRs to great depth, using DPVs and carrying cameras. I have dived my COPIS to depths exceeding the interstage pressure of my 02 first stage a few times, including a couple of dives with my CUDA. I know that it CAN be done. Simply put- I didn't like it. The task loading was more than I wanted to deal with.

I feel strongly- after chewing this over for more than a year- that this is the right step for me. I have all the paranoia and anal-retentive p02 monitoring skills that any good mCCR diver should have at this point, after 3 years and hundreds of hours diving manual.

Anyway, I'm pretty excited about making this jump- and I look forward to this next evolution in my dives.

[CaptnJack]

How many dives are you doing beyond mCCR range a year? Since when did you get a camera??! I want pics!

[Joshua Smith]

How many dives are you doing beyond mCCR range a year? Since when did you get a camera??! I want pics!

Not too many. Only a handful of dives that deep so far. They all worked, but they all made me think hard about making this change, too.

No camera, just a CUDA. Most of my personal "big dives" are recorded somewhere on Dan's site, if you know where to look.
2010 hasn't been a great diving year for me, for a lot of different reasons. I'm making some big plans for 2011 right now- and this conversion is part of that.

[ljjames]

ASP!!!!

[rjw]

You'll like the APECS Josh.
I however have decided to disable the solenoid in mine. Fully manual RB's seem to be all the rage lately. (inside joke)

[limeyx]

You'll like the APECS Josh.
I however have decided to disable the solenoid in mine. Fully manual RB's seem to be all the rage lately. (inside joke)

Oh really ? Can you tell me more about that ?

[Joshua Smith]

Well, I made the trek to ISC's spiffy new factory today. Dropped my head off for modimificationizing. They say I should have it back next week.

[lamont]

any thoughts on hCCR with both the CMF and the electronics?

[Joshua Smith]

I don't really know much about the hybrids, other than that it seems like a good idea.

OTOH, its hard for me to understand how one could be so unawares as to let your loop go hypoxic with a cmf. It would take something in the neighborhood of 10-15 minutes for that to happen, and if you're really going that long ignoring your hud and failing to check your p02, maybe you shouldn't be diving a ccr. Another thought I've heard from experienced eCCR divers is that the solenoid on a hybrid only kicks on when the p02 of the loop is dangerously low...so it operates very infrequently. Which means that the operation is seldom verified by the diver. And that leads to a different kind of danger. The thought process here is that its safer to have critical gear operating frequently, so that the absence of function is obvious. I don't have much of an opinion either way on that, just repeating what I've heard other people say. For all I know, I might end up deciding hybrid is the way to go,eventually.
At this point, all I can say is that I understand mccr pretty darn well, and now I want to learn more about eccr. There are subtleties to them both that are difficult to put into words sometimes. Like, when I first started diving closed circuit, I kept plowing into the bottom, inhaling for all I was worth.
( doesn't work with a constant volume of breathing gas,obviously). Now, I'm going to have to teach myself not to start adding 02 to the loop manually when I ascend. That habit is so ingrained by now, I don't even think about it, I just do it.

[camerone]

Now, I'm going to have to teach myself not to start adding 02 to the loop manually when I ascend. That habit is so ingrained by now, I don't even think about it, I just do it.

Nothing wrong with that habit, even on eCCR. There are two schools of thought on eCCR. One is the "mCCR" school, which is you always run the setpoint controller at low setpoint (generally 0.7 atm) and you fly the loop manually to keep the PO2 where you want it. The solenoid is a parachute, but you'll verify it before the dive when the unit starts up.

The other school is the one I subscribe to, which is just run the thing at high set point on the controller once you've finished your descent, and let the unit do its job. You can still add O2; on ascent I'll often add O2 to run at a higher PO2 to clear out the deco faster...leave the setpoint at 1.3, and boost it to 1.6 the whole way up. Deco's cold in Seattle, damnit

[lamont]

Another thought I've heard from experienced eCCR divers is that the solenoid on a hybrid only kicks on when the p02 of the loop is dangerously low...so it operates very infrequently.

can't you still use a setpoint of 1.2 or whatever and then the solenoid will kick on whenever it gets lower than that (but the CMF would make it operate less frequently)? so you don't necessarily have to set it dangerously low...

i'm also not sure about the logic of flying entirely mCCR, but having the eCCR as a fallback to prevent hypoxia -- like you said, if you're not testing it, you're not sure that safety net will actually work when you really need it...

it still seems to me like the CMF could be a useful addition to an eCCR to allow the diver more time to sort out trouble, and as an added protection against going hypoxic... i don't really see the downside, unless you count the solenoid firing less to be a downside...

[Joshua Smith]

No, I think you may be onto something, there.
The way I look at it, I have a pretty good grasp on mccr at this point. Now, I want to get an equal amount of experience with the electronic version. And I wouldn't be too surprised if I end up with a hybrid someday.
But- and this is just my own opinion, based on conjecture and speculation- as much as we worry about hyper/hypo-oxia, I think most ccr fatalities are probably due to poor maintenance, sloppy checklists, and diver carelessness.

[CaptnJack]

as much as we worry about hyper/hypo-oxia, I think most ccr fatalities are probably due to poor maintenance, sloppy checklists, and diver carelessness.

Yeah we sure don't hear about many issues on known functioning units. Good luck with the eCCR toys.

[Joshua Smith]

Well. I should have done this a while ago. I finally dived the new unit today up at Muk. It was sweet. Very interesting watching the solenoid do its thing. The p02 is much more stable than I could ever do manually. I'm really going to enjoy this- especially on scooter dives when I have my hands full. One happy surprise for me was that adding a few pounds of batteries and stuff to the head made my Meg trim out nicely.

[rjw]

Well. I should have done this a while ago. I finally dived the new unit today up at Muk. It was sweet. Very interesting watching the solenoid do its thing. The p02 is much more stable than I could ever do manually. I'm really going to enjoy this- especially on scooter dives when I have my hands full. One happy surprise for me was that adding a few pounds of batteries and stuff to the head made my Meg trim out nicely.

The Sampson is calling YOU

[Joshua Smith]

Oh, hells yes! It's so much easier now, especially for task loaded dives.

[ljjames]

YAY! i knew you'd love it!!!!!!!!!!!!!!!!!!

[Joshua Smith]

YAY! i knew you'd love it!!!!!!!!!!!!!!!!!!

OK, I have a question- do you understand the Automatic Set Point option? I read through the manual, and it doesn't make any freaking sense- why would you choose ASP instead of, well- just choosing a set point?

[ljjames]

say you are on the surface, getting ready for the sampson, current is rip snortin' but you expect calmer on bottom. you have to scooter down the line. do you have a free hand to click it from manual (or lower setpoint) to desired dive setpoint? probably not.

asp automatically brings it up without causing the solenoid to go nuts in first 20' like if you put it on 1.2 on surface. as i understand it, as you descend it holds the 'last highest' ppo2 as you increase pressure, it doesnt let it drop, allowing your descent to drive it up, and then holds it at the number you selected, as opposed to taking it right up to 1.2 (or whatever you selected as setpoint) from the moment you select it via the solenoid...

i hope that made sense, let me know if it was just more confusing

[Joshua Smith]

say you are on the surface, getting ready for the sampson, current is rip snortin' but you expect calmer on bottom. you have to scooter down the line. do you have a free hand to click it from manual (or lower setpoint) to desired dive setpoint? probably not.

asp automatically brings it up without causing the solenoid to go nuts in first 20' like if you put it on 1.2 on surface. as i understand it, as you descend it holds the 'last highest' ppo2 as you increase pressure, it doesnt let it drop, allowing your descent to drive it up, and then holds it at the number you selected, as opposed to taking it right up to 1.2 (or whatever you selected as setpoint) from the moment you select it via the solenoid...

i hope that made sense, let me know if it was just more confusing

And that's better than just descending at .5 or .7? I guess I can see it- I'll have to give it a try and see what I think. Do you just leave it on auto for the rest of the dive, until you're back in the shallows? Or do you switch it to 1.2-1.3 on the bottom?

[ljjames]

thats the beauty of it... you can make that decision once you are down there... it will hold at whatever you set for max PO2... When i've used it, i've done both... I left it on ASP for the dive or switched to setpoint to see how it differed, and then done the standard switch back to lower setpoint at 20' (something the solenoid can maintain without constantly having to add - AKA making buoyancy more difficult for yourself if you forget)

[Joshua Smith]

Ok, I get it. Thanks! I'm gonna have to play with that to see if I like it or not, but I like the idea.

[Marc]

Let's get in the water. this week, next?

[Joshua Smith]

Let's get in the water. this week, next?

Definitely! Except I just sent my regs in for service...should have them back next week sometime. I could do a monkey dive any time, though...

[ljjames]

monkey monkey monkey!!!!!!!!!!