Why CCR?

[HowardE]

With all due respect. You're missing the point.

 

[Michael_Lambert]

Why would 20-30 hours of CCR time be referred to as the "death zone" (TDI Evolution manual)?

Many find the first 20 or so hours the hardest, Just like anything your working out new gear, new weighting... You working an all new type of buoyancy control. Many will consider it a "Death Zone" as divers tend especially on Manual units get themselves into trouble as they are paying attention to their gear trying to trim out or fighting there buoyancy not realizing their PO2 is creeping up or down.

I know when my dive buddies made the move to the Kiss Classic, we as a team spent 100+ hours in less than 40 feet of water before we started doing the 80 foot + dives or decompression dives.

 

[Jax]

Intresting -- I understand that "death zone" concept. In motorcycling, the most dangerous 'zone' is (a) a new motorcyclist in his/her first year of riding, and (b) an experienced rider on a strange bike.

The inexperienced person has to experience issues and react appropriately to survive . . . sometimes unscathed, sometimes not.

The experienced person with strange equipment must practice with that equipment and all its abilities and shortcomings until s/he is experienced with it, or risk doing what 'experience' says is the right thing, but is very wrong with that new equipment.

A good rider will not take a new bike into complicated situations (read DC or LA traffic) until s/he has done a great deal of local neighborhood and rural riding and puts it thoroughly through its paces.

I SWAG that the 20-30 hours with CCR in 'safe' environments is for the same thing - is that right?

 

[Rick Inman]

Bailing out on a trimix dive is different, especially when you have a deco obligation. Switching from optimum gas to non-optimized gas at depth causes the deco to pile on. It's a whole different set of rules. Maybe some people can figure it out. Maybe not?

I've read this before, but I don't find it to be the case in practice.

When I've done BO drills (from as deep as 200'), it hasn't been much more difficult than just doing OC deco. Yes, you have to manage the gas in the lungs. Yes, you have to switch to an OC profile for deco. But if you have experience doing OC deco, this shouldn't be a big deal. I used VP and ratio deco when I dived OC, and after you've done a bunch of those you get to know the deco stops in your head at various times and depths close enough to get out clean if you needed to. So even if your computers crap out and you can't find your back-up tables or your buddy, a little common sense applied to experience should get you out without too much trouble.

As to switching from optimum gas to non-optimized gas at depth, I fly my eCCR unit manually at 1.2 at depth, and my BO should be 1.0 at the bottom. If I bail, I'm on the way up, so a couple of breaths at 1.0 isn't going to "pile on the deco".

Say you do 20 mins at 200' and you're flying at 1.2 and you have to bail. In your head right now, can you estimate your total deco (to get out) time? Your first stop depth? Your time at last stop? If I could not be darned close in my head on the fly, I wouldn't be comfortable doing that dive on CCR. But that's me, I'm a big chicken.

Now, with all that said, my BO drills have all been pretty stress free. I supposed if I was bailing from some sort of catastrophic failure, or from a major hypercapnia event, things might not seem so simple. :shocked2:

The answer is, in IMNSHO, to continuously drill, drill, drill, so when it really does hit the fan you're not desperately trying to respond, react, and remember what the heck you are supposed to do. It has to be second nature. But this was my OC principal as well, and it hasn't changed going ccr. I'm really chicken to die underwater, so I work really hard to be good at not doing so.

Oh, and one more thing. This is a fun thread!

 

[DCBC]

Intresting -- I understand that "death zone" concept. In motorcycling, the most dangerous 'zone' is (a) a new motorcyclist in his/her first year of riding, and (b) an experienced rider on a strange bike.

How does this stack-up to with the increased danger of comparable sports (flying comes to mind). If the accident rate is significantly higher, is this attributable to the short training program given by many CCR Instructors?

 

[Jax]

How does this stack-up to with the increased danger of comparable sports (flying comes to mind). If the accident rate is significantly higher, is this attributable to the short training program given by many CCR Instructors?

I'm a little confused with flying and short CCR class . . . ?

I look at what you CCR folks are saying from a training standpoint (my forte), since I have zilch CCR knowledge.

No matter the environment - riding, flying, parachuting, welding, driving . . . The experienced individual performs well with the equipment with which s/he practices.

As soon as you change something -- the environment, the equipment -- there are new parameters in play that detract from that practiced performance.

A new (different) plane, for example, will not perform the same as the 'old' one. I understand that the FAA requires pilots to 'certified' on certain planes, airfields, etc. It was one of the points brought out in that New York crash. The pilots did not have a lot of practice flying that particular "iced" plane.

So, if an experienced diver is on new equipment - with the assumption that the diver understands that equipment (not going into short, long, quality of class) - s/he will still not be at their peak efficiency until well-practiced on the equipment. (at the rec depths)

So, after becoming practiced on the equipment, the CCR diver goes to diving 'deep'.

Therefore, one would assume if a person is a new CCR diver (less than 30 hours, say), and s/he goes 'deep' "right away", the s/he has two "new" parameters - the equipment and the environment. The risk, I believe, will go up logarithmically.

Y'all chime in if I'm off base here . . . I'm trying to assimilate this into what I know.

 

[Cave Diver]

One point here. You mentioned the electronics you use as a backup in case your attention span wonders off. Just how much of a gap in your attention span can hurt? I make fun of myself on cave dives cause my light goes everywhere. I take it all in. But I do manage to keep my gas under supervision, I check it every 2 to 3 minutes. Is that too big of a gap for CCR?

I thank everyone so far for the answers.

Depends on your comfort zone. If I intend to maintain a PO2 of 1.2 during a dive, I may set my controller for a 1.0 or 1.1. Depending on depth, I check my PO2 on my handset every 3-5 minutes.

So lets say it's been two minutes since I last checked. Suddenly my primary light fails. My first action is to stop and secure the line. Next, find my backup and turn it on and when I do that, I realize that the line has reached out and grabbed my light canister and I'm "stuck," so I take a moment to clear it.

While I'm doing that, I hear my solenoid fire because I would normally have checked my PO2 and added a squirt of O2 by now. As soon as I hear that, it instantly brings my focus back.

Is a drop from 1.2 to 1.1 dangerous? Most likely not. But actions become habits. I think that relying purely on electronics causes complacency. Then if you have an electronics failure, by the time you notice it, it's too late. Plus, you dont have the muscle memory for flying the unit manually at that point.

 

[DCBC]

So, if an experienced diver is on new equipment - with the assumption that the diver understands that equipment (not going into short, long, quality of class) - s/he will still not be at their peak efficiency until well-practiced on the equipment. (at the rec depths)

So, after becoming practiced on the equipment, the CCR diver goes to diving 'deep'.

Therefore, one would assume if a person is a new CCR diver (less than 30 hours, say), and s/he goes 'deep' "right away", the s/he has two "new" parameters - the equipment and the environment. The risk, I believe, will go up logarithmically.

Say I'm a newly certified recreational diver (air/nitrox). I purchase a CCR and want to take instruction. No minimum number of previous dives are required for me to commence the training program. I'm not centering out IANTD here, but an example may be beneficial.

IANTD Prerequisites:

Open Water CCR (Max depth 100'): Nitrox Diver, No other requirements
Course duration: 5 hours in-water training, 4 dives

Normoxic trimix CCR (Max depth 200'): 100 dives, of which at least 30 were deeper than 90 FSW, 20 dives and 25 hours on the CCR being used. No decompression experience required.
Course duration: 5 hours in-water training, 4 dives

Trimix CCR (Max depth 333'): 200 dives, 50 hours of dive time is required on the specific Rebreather for which the diver is being trained.
Course duration: 2.5 hours in-water training, 2 dives

I'm sorry, but I don't think a diver is ready to be certified with CCR to 200' with less than 5 hours of decompression experience. Additionally, I can't see how the person can add 25 hours on a CCR and in 2.5 additional hours and 2 dives can be certified to dive to 333'! Where's the deep water experience?

If there is a "death zone" (less than 20 hours of CCR use) the answer is to add 30 hours of experience and go from 100' to over 300'? I don't get it. I would think that the training times would be increased prior to initial certification by 20 hours and remove the "death zone" entirely. Increased training times have been beneficial for other recreational activities (including flying).

 

[Kevin Carlisle]

Depends on your comfort zone. If I intend to maintain a PO2 of 1.2 during a dive, I may set my controller for a 1.0 or 1.1. Depending on depth, I check my PO2 on my handset every 3-5 minutes.

So lets say it's been two minutes since I last checked. Suddenly my primary light fails. My first action is to stop and secure the line. Next, find my backup and turn it on and when I do that, I realize that the line has reached out and grabbed my light canister and I'm "stuck," so I take a moment to clear it.

While I'm doing that, I hear my solenoid fire because I would normally have checked my PO2 and added a squirt of O2 by now. As soon as I hear that, it instantly brings my focus back.

Is a drop from 1.2 to 1.1 dangerous? Most likely not. But actions become habits. I think that relying purely on electronics causes complacency. Then if you have an electronics failure, by the time you notice it, it's too late. Plus, you dont have the muscle memory for flying the unit manually at that point.

I like how you explained that... Now I like how you fly yours manually and have the electronic bckup, makes sense to me versus only relying on the unit. Since you mention cave, here is my biggest concern.. I have been in a blackout, how in the world would you monitor this? If you had the manual only system I think this could be a very bad situation...

 

[HowardE]

I think that relying purely on electronics causes complacency. Then if you have an electronics failure, by the time you notice it, it's too late. Plus, you dont have the muscle memory for flying the unit manually at that point.

When I'm diving the Evolution, I fly it in Auto, but I do check my handset every 2 minutes. I also hear the solenoid fire, and try to mentally predict when it will fire.

I know how to, and practice manual flight, just because.

eCCR can cause complacency, but also knowing that complacency kills, I personally, am diligent.