split from Trimix in 100 dives

[Thalassamania]

I'm guessing Eagles Nest, but I doubt they were wearing split fins.

The Deco Stop see post 162


Edit: They were both wearing Jets with springstraps. So once again Nereas is full if $%it

Yah think? Could his eyes be brown?

 

[Mike Ange]

Actually after training well over 100 divers on various rebreather systems I find the biggest issue for new divers is breaking bad habits acquired on open circuit. Divers training on CCRs or SCRs very early have fewer bad habits to break. Some agencies have allowed distinctive specialties where open water students never used open circuit at all except for as a bail out system. These courses have had limited commercial success but a great safety record. Now there is a new training agency forming in Sweden that will specialize in training brand new divers on CCRs from the start.

One of the bad habits open circuit divers generally acquire is complacency. You do not have to monitor your equiment because when it fails you either cannot breathe at all or you get more air than you can handle and then you just ascend or go to your buddy. The CCR requires monitoring your equipment with a different respect and this is a skill best learned right out of the box - in fact it would be a great skill accident reducing skill for open circuit divers as well if it was still taught effectively.

Safe Diving,

 

[mempilot]

I will share something I wrote on Rebreather World in regards to justifying rebreathers for every dive. I think it is relevant to this thread here.

I made the progression, or transgression

, from technical OC to CC about a year and a half ago. I live 15 minutes from a bucket load of wreck diving, and I make about 100 dives a year. Most of these dives take place between 50 and 75m in open water with penetration. My plans include cave training (4 hour drive access to Ginnie, etc...) and much more technical dive travel (have a lot of free time

) in the near future.

My decision to go CC was based on simple logistics, full well knowing that I would be engaging in a more risk adverse sub-culture of the sport of diving. For a dive to 66m, I was lugging double 95's and other essential gear that would be equivical to what is needed for CC. The weight difference between the doubles and the Rebreather is significant enough to make an impact on the body over years of boat diving, but an even bigger difference was the amount of mix and ean that I would go through in a year of OC diving vs CC diving. Now, my deco bottles very rarely get emptied, and my deep bailout get exercised semi-frequently (cautious bailouts, practice, etc...). The cost of my diving went down dramatically and there are many less trips to the shop for fills, etc... My back and joints feel better from the light load being lugged up the ladder in 4 to 6 foot seas as well.

The nice thing about doing most of my wreck dives in warm water fairly close to shore is that we can do 3 hour trips with one deep decompression dive or a 4 hour trip with one light decompression dive followed by a shallow drift dive (think lots of run time and infused with skills practice). The net is that in the approximate 100 dives per year, I get much more bottom time, and for a much reduced cost. The initial cost of the gear is 'sunk cost' and amortized down to a depreciated value much like the purchase of a motorcycle or other expensive hobby asset.

In this CC time, I've focussed on technical diving until recently. Karen decided to get into diving (strictly recreational endeavors). We've done some local diving and recently returned from a nice trip to Bonaire. In the 20+ dives that I've completed with her, all were done on OC. My attitude in the past was that I would only dive CC, even on this trip and any other recreational dive that I did with Karen. However, while my CC plans move into cave, I've rekindled my love of the shallow reef. We had the best time just jumping in and seeing what I've been missing for the last year and a half. The complexity of diving with a CCR diver is really not all that fair to Karen, and I decided it wasn't worth it to use a 50 lb sledge to hammer in a tack.

A friend and I were talking yesterday over dinner about his choice of what he likes to call 'tools'. He has a son that he likes to dive with; and therefore, chooses the correct tool for the job: OC. He also enjoys cave diving; and therefore, chooses the correct tool for those overhead dives: CC. He does enough of each category to be profficient with both types of gear. I used to subject to the theory that all dives needed to be done on CC once that route was committed to. However, I'll do what I often do, and compare Rebreather diving to my occupation of flying. Aircraft are infineatly more complicated pieces of life support equipment, and I am trained and profficient on several different aircraft types. If I haven't flown a particular type in a while, I don't push the limits until I am back up to speed. Sometimes this means recurrent training or practice in benign conditions. In my diving, I rarely go more than a few weeks without getting wet.

I have to agree that there are the right tools for every job, and without making too much of it, I feel the human brain is able to remember how to use a hammer vs a sledge and vice versa, even with some surface interval in between.

Karen and Bonaire rekindled my love affair with shallow "look at the pretty fishes" type diving. In serious thought on the matter, the Rebreather is not the right tool for that type of diving anymore than the single AL80 is the right tool for 200 feet deep or 3000 foot penetrations. As my diving could go to both extremes, both setups will remain in my toolbox. That just means my attention to detail will have to remain vigilent, and my dedication to skill retention will require plenty of practice and setting my limitations appropriate to my currency.

So, safety may be one reason for limiting the use of CC. Logistics may be one reason for increasing the use of CC. But, what I've found just recently is that tools are tools, all with varying levels of safety decals plastered to them.

Knowledge, Training, Profficiency, Practice, Experience, Limitations

Live it for every tool you own.

I set Karen up with a Hogarthian style rig when she started OW training. We debated having her go CC from the start, but decided against it for the following reasons:

1. CC was not the appropriate tool for the diving she would be doing for the next year or two.
2. We wanted her to be comfortable in the water and not have to worry so much about monitoring a rebreather

We wanted to make sure she would like diving before throwing a more complex life support system at her. If she had had a malfunction early on, she may have opted out of diving early. Not a big deal, but to invest over $10000 to find out you don't like it in the end would have been silly.

The Hog rig will be easily converted to a rebreather setup down the road if she chooses to go that route. Nothing, other than the constant FO2 dive computer will be wasted in the transition if she decides to go that route.

Now, with all this being said, I would not hesitate to let someone go CCR from the beginning if they understand the benefit/risk comparison. It is a bigger commitment in both gear, training, and attitude to go CCR, and to do so without the appropriate understanding could have dire consequences. If one is preparred and dedicated with the right mindset, then it can be an enjoyable thing.

 

[mempilot]

And with a CCR, you are as likely to die whether you have 50 or 500 dives. It really doesn't matter what your experience level is. Poof! Your equipment malfunctions and you are history. Nothing you can do about it, except plan your estate, finish your will, pay off your bills, and kiss your wifey goodbye.

You have to be careful with comments like this. While the rebreather is a machine that can kill if the user is complacent, it can also be a 'time machine' in certain events that OC would surely kill. Most malfunctions on a rebreather are dealt with via protocol, much in the same way an OC technical diver isolates a leak. Dealt with in a calm manner, the CCR diver has many more options than an OC diver when dealing with many situations. Some rb failures can be fatal to a non-skeptical diver. Vigilance is neccessary. You must think it is going to kill you. That way you are ready when it tries. However, all of these attempts can be dealt with by an astute diver.

The more appropriate statement would be, "With a CCR, you are as likely to have a problem you must deal with whether you have 50 or 500 dives." To assume these problems dictate death is an emotional reaction to incidents and accidents that have taken lifes, but ignores those that have been dealt with and had positive outcomes.

Doubles work well down to 350 ft. Deeper than this and you would be in CCR country. Shallower than this and a CCR is definitely inappropriate, unless you are filming videos professionally. And even then, you would want somebody with twin tanks watching your every move. Particularly if you stop moving!

The logistics of a 350 fsw OC dive are much greater than the same dive being completed on CC. The 2003 and 2006 Britannic expeditions are the perfect example. The mandatory switch to CCR by the second expedition team was gleamed from the logistical issues uncovered by the first team. The logistical benefits of CCR back up quite shallower than 350 fsw. Most of my diving takes place in 150 to 250 fsw. I have recognized the benefits of CCR in this depth range and would defend them if needed.

There is never a need to share gas with me.

I carry more than enough for myself, and a rule of thirds reserve on backgas for them as well.

I find this to be somewhat arrogant and a missunderstanding of the potential risks in technical diving in general. I have had an o-ring let loose, as has a buddy. Mine was on a BOV connection, and his was on a 1st stage bailout bottle. A .05 part can fail on your OC rig just as easy. If that happens, you will need gas from a buddy since your thirds could be reduced to an inadequate volume.


Your blanket statements hold some truths, but they are clouded by sensationalism. I think if you tone down the rhetoric, your posts would be better received for debate and discussion.

 

[Gill Envy]

I am telling you that you are taking a huge, unnecessary risk, if you are diving with a CCR where you could instead be diving with O/C twin tanks. My statement is technically a conclusion, which is a form of opinion, but it is also very close to being a self-evident truth. You don't have to like truth. You can ignor it if you want. You can dive anyway you want. What you do, and what I do, are two different issues.

If you are diving with a CCR in places where O/C twin tanks cannot go, then that is a different story. In that case, the risk, whatever it is, simply needs to be warranted, and mitigated.

Nereas, thanks for sticking your neck out and being honest about your sentiment, I suspect your conclusions are much more representative of the OC crowd than any CCR diver on this board wants to admit. It's no surprise this is such a quiet corner of Scubaboard when the natural trepidations of of OC divers are met with such animosity. Rather than blast you out of the water, I think folks should be a bit more understanding of where someone like you is coming from.

Let's see, I think it might be valuable, for instance, to consider how you could possibly have come to the conclusions that you hold? Perhaps it's all the fatalities that are happening, consistently, every month on CCR's? Seems understandable to have a pretty cynical attitude toward a sport that is claiming something like 1% of it's users. I mean seriously, how can any of us blame someone like you from having such an attitude. Frankly it's amazing that so many of us get past such a natural conclusion.

When I first started getting curious about rebreathers I went to my old dive club to pick the brains of some of the old salt CCR divers, having not gone to a meeting in years I went with renewed excitement. Low and behold they were holding a memorial for an instructor that used to fill my OC bottles at the local shop... he had just died on, you guessed it, a rebreather. this put quite a chill down our spines and dampened our interest in rebreathers. but the siren call kept me coming back around and instead of running out and buying one I instead made my pursuit all the more serious an endeavor. I took 6 months and hundreds of hours of time interviewing local CCR divers, posting questions to boards like this. I gave this decision more careful consideration than any other single thing I’ve taken on in my life. I was fortunate to know some very experienced folks right in my back yard. I tried to get familiar with all the choices of rebreathers, pool diving as many as I could, certain that the wrong decision could cost me and or my wife our lives. We ended up with the most fandangled, fool-proof rebreather available. Over the next year a very disturbing combination of uncanny bad luck and stupid mishaps occured, radically changing my perspective about the habit/design/risk debate. I began rethinking my choice, connecting a lot of dots. Didn’t take long before we sold what we thought was the safest rebreather available.

For us, and I can't speak for everyone, it appeared that the fully automated version of rebreathers did in fact have a tendency to reinforce complacency and that yes, ultimately this was leading way to many people to make relatively simple yet fatal mistakes, weather they originated from malfuctions or simple user error.

Nereas, I agree with you to some extent, but with a twist. there is a vast difference in habit and design and thus risk between fully electronic rebreathers and manual injection ones. A strange counter intuitive paradox appears to exist, eCCR's appear to be suited best not for the lazy diver but for extremely anal divers, people who are capable of resisting the "function creep" of automation, people who will volluntarily cultivate paranoia of the system within themselves and never let their guard down. the majority, 99% of eCCR divers seem to be able to do this, while a horifying 1 to 2 % appear to be succumbing to a myriad of pitfalls and sand traps. It is clear to me, make sure you truly need the automation and that you are capable of maintaining the appropriate attitude before embarking down the eCCR road.

I know what I’m about to say will sound like the broken record creed of a cultist with some hidden agenda, but I will repeat it in yet another time and yet another way because I truly believe that there is a rebreather out there for folks wishing to extend their range without the downside of doubles and without the risk of death associated with eCCR's.

After having put relatively extensive hours on both manual injection and auto set point style rebreathers I do believe that the mCCR system is self reinforcing and remarkably "safe" because it presents no illusion about who is in control and ultimately responsible for life sustaining action. Remarkably, but not really, our brain, after adequate training a practice is more reliable than a computer, more conditionable to deal the a consistent threat than an obscure, unpredictable one. Our brains are able to deal with the nuances and preemptive habits necessary to deal with the wide range of possible break downs and mistakes that come with rebreathers.

There are some 800+ mCCR's in use, there is one fatality associated with them, roughly 1,000 users to 1 fatality vs 100 eCCR divers to every 1.7 fatalities. Yes it’s a smaller sample group, but it’s grown exponentially over the last few years with many challenging dives being performed manually. I seriously questioned if this statistic was an anomaly, then I spent a year diving an mCCR after spending a year diving an eCCR. I would put the challenge to any eCCR diver who thinks this proclamation is a pile of rubbish... dive one for a year, then tell me what you think, I think you’ll agree that it's undeniable why there is such a huge difference in fatalities and that with practice, you can do practically anything with an mCCR that you could with an eCCR as long as you respect the limits of your expanding abilities.

If you want to dive a rebreather within recreational limits, I highly recommend at least starting with a manual injection system and seeing if it's enough. Most folks who start on mCCR's never switch away from them and before long are comfortable going much deeper for longer than they could have previously imagined. They are more reliable, field servicable, more economical to purchase and maintain and yes, they do appear to lead to fewer fatalities.

Imagine being able to spend 2 hours on your favorite recreational dive, exploring every nuance and crevice, spending the bulk of your time in the sweet spots, only racking up a few minutes of deco, an hour into the dive, still below 70 ft… ending the dive feeling refreshed, without the nitrogen burn you are used to, try doing that on a set of doubles and see how you feel afterwords. who knows, you may just find that you become comfortable being called a "tec" diver. If you are like me, you might just go from a single tank diver to someone becoming a lot more friendly with the idea of tri mix even.

 

[WD8CDH]

Doubles work well down to 350 ft. Deeper than this and you would be in CCR country. Shallower than this and a CCR is definitely inappropriate, unless you are filming videos professionally. And even then, you would want somebody with twin tanks watching your every move. Particularly if you stop moving!

I never realized how bad of I diver I was.:shocked2: I guess at least 1,500 of my rebreather dives were inappropriate.

Nereas, how many rebreather dives have you made to back up your statement?

 

[PeCeDiver]

And even then, you would want somebody with twin tanks watching your every move. Particularly if you stop moving!

The poor OC chap is going to have to shlep a whole lot of tanks to do the same bottom time and the price for the helium will be very high.

 

[Mr.X]

Nereas provides a lot of entertainment. However, the caveat being rarely ever any solid, or real-world knowledge.

Also, I did not realize that there were depth usage rules with regards to CCR, OC & underwater videography. Since, I happen to instruct in both areas and shoot video..I'se wonderin' who set dem' rules?


X

 

[silent running]

Hello all, I waited to post on this thread due to the high noise ratio, but now that a few actual CCR divers have posted, I will too.

I moved to rebreathers after less than 100 OC dives. First, I trained on the Dolphin/Atlantis SCR semi closed rebreather and enjoyed it's benefits over OC-better wildlife interaction, longer dive times. When I switched to SCR 10 years ago, there were no American made CCRs, so it was SCR or nothing.

After about 150 hours on SCR, I began to consider buying my own RB. I bought the only book on RBs I could find and started talking to other RB divers. Being familiar with the setup and operation of a constant mass flow SCR, I compared it to the newly available American made electronically controlled closed circuit rebreather, the Prism. I found that for the same amount of prep time/trouble, I could have more than 3 times the dive duration, no bubbles at all-except during ascent-and huge advantages over both OC and CMF SCR for deco diving. So, I decided to save up my pennies and buy a Prism ECCR. After more reading, a year of waiting and a very intense 4 day course, I became a CCR diver. Since that time, I have taken 15 overseas trips and enjoyed many, many exceptional wildlife encounters not possible on OC, the freedom to plan my dive day as I like and done some deep tmix dives much more easily than could be done on OC or SCR.

I took my trimix class after about 400 hours on the CCR. The class was taught by 2 veteran Navy divers, who completely wore me out in 5 long days. I enjoyed it immensely as I enjoy learning about diving and my own physiology almost as much as I enjoy actually diving.

Do I think somebody could handle going from no experience to CCR tmix in 100 hrs? Yes, but I wouldn't recommend it. I know that in my particular case, understanding all the physiology of constant PO2 diving and exactly how my ECCR works, both things I consider crucial to being a safe CCR diver, took a good while to sink in. Learning about tmix CCR diving required me to take a further crash course in OC technical diving as the rules of proper bail-out required, and it was definitely an overload and also took quite some time for it to sink in.

But in the end, I believe it is all a matter of what your motivation is and how much you enjoy diving. If I had 100 hours of diving and the time to prepare for those hours properly, free from too many distractions, I think it is possible to absorb the bulk of the learning and become physically comfortable with the gear. But again, I wouldn't recommend it. -Andy