Second Thoughts About Rebreather Class

[ccrprospect]

Hello

I am a qualified tec diver (up to normoxic trimix range) and was recently thinking of making the switch to CCR. After a try dive and reading a bit about rebreathers, I decided to sign up for a MOD 1 class.

Subsequent to my registration, I read everything I could find online about rebreathers. I ordered and read Jill Heinrith's book on the topic, and then read the manual for the unit I will do the course on. I was shocked by the amount of statements along the lines of "rebreathers can kill you without warning", "you should talk with your family about your decision to dive on rebreathers", and Heinrith's "big sister" talk interspersed throughout her book. These are not the standard waiver of liability clauses you encounter in scuba - these are real warnings.

I read about the limitations common to all units, and that even though the vast majority of rebreather accidents can be attributed to diver error/carelessness, (a) oxygen sensors are not necessarily the most reliable piece of technology and are implicated in "unexplained" diver deaths and (b) CO2 breakthrough can occur despite proper scrubber packing and can render you unconscious without warning. I read about instructor trainers dying.

I was tremendously excited about that class and I am still sort of interested, but now with GREAT trepidation. I know there is risk in everything in life, but do CCRs simply pose unacceptable risk? I am doing this for fun - I do not NEED a rebreather. I wanted to take the course to save on helium costs, enable longer bottom times, and because I believe that CCRs are the future of deep diving in face of the worldwide helium shortage. But is the risk worth the reward? Especially risk due to outside, uncontrollable factors not attributable to diver error?

 

[tbone1004]

are they dangerous? yes
are a lot of those things CYOA policies? yes
Are many of them scare tactics to make instructors feel better about themselves? yes

If they proved unacceptable risk, the market wouldn't be growing as fast as it is, and we would have more deaths. Many/most of the accidents being talked about in that book are VERY old and similar to open circuit cave diving, the deaths have fallen drastically over the years.
They can kill you, and they can kill you without giving any active warnings *most don't have beeps or haptics*, but they will try to warn you on the screen about ppO2, and you need to learn about how to recognize CO2 problems. If you are paying attention, you will notice.
Good instructors will help teach you the ways to foresee those warnings and prevent them in the first place. You should always have a healthy respect for any rebreather, but if the non-diver risk was as bad as they'd make you seem, then we would have a LOT more deaths on CCR's every year. As it stands, we have exceedingly few, and I can't remember the last one that wasn't easily and obviously attributed to diver error.

 

[grantctobin]

For me, it is. However, that decision is one you must make yourself. If I had a slew of dependents, I would re-evaluate and won’t pretend I can answer that question without already having had children. I don’t feel that my opinion would change. The types of things that can harm you on a rebreather are obviously different than those on open circuit. At the same time, I would argue that planned and executed properly, especially in an overhead environment, rebreathers are a much safer choice.

Have you bought a unit already? If you have not, why not rent one for the duration of class and then determine if CCR is truly for you? At worst, you determine it is not your cup of tea and you walk away with an even more in depth understanding than you already have and are a safer member on a mixed team or in a support role capacity. At best, you develop an explicit understanding of the risks and your own risk tolerance and decide it is for you.

There are extraordinarily few errors not attributable to diver error. Analyzing gas day of, religious unit and scrubber packing, meticulous replacement of sensors, overly conservative bailout volume (I don’t believe there is such a thing as too much bailout), having your gas on, proper dive planning, and electing to thumb the dive if you feel something is off or you are not comfortable will all aid you in this pursuit.

There’s a few excellent CCR instructors on this board that generally pine in on this type of question including Ken Sallot and James Draker, among others. A search through the forum will bring up some of these.

 

[Pandora's Box]

I do not NEED a rebreather

Sounds like you know the answer already. The costs and risks of CCR are not worth it (imo) unless the type of diving you are doing would be more risky/expensive without it.

Check this out (if you haven't already), especially Pt.6!:
http://www.haynesmarine.co.uk/images/stories/A Survival Guide To Rebreather Diving Nov 2011.pdf

 

[michael-fisch]

"Especially risk due to outside, uncontrollable factors not attributable to diver error"

Deciding to dive a rebreather is interesting and is at least 10x more likely to kill you than diving recreational SCUBA.
All errors are always attributable to diver error though. A rebreather used by a careless diver will be resold, the diver that used it will end up in a funeral home.

Now how do we have many good fun dives with a rebreather?
Never switch your brain out of gear, learn as much or more about your rebreather as the manfacturer or instructor on your rebreather knows, always carry bailout gas in tanks with working regulators, don't let yourself get stressed out.

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A ScubaBoard Staff Message...

Readers should be aware that the next statement is hotly debated later in this thread. @michael-fisch is a very experienced diver, and we are not inclined to delete his comment. However, experimental data by our own renowned @Dr Simon Mitchell has revealed that there is a significant percentage of divers who will not know that they are becoming hypercarbic. Therefore, an experiment as suggested below may, for some divers, be fatal. We understand the temptation to "find out what it feels like." However, this practice is not recommended by any training agency, due to its inherent and unpredictable danger.

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After you get used to your RB, do a few dives without changing the scrubber so you get a chance to learn how the start of a CO2 hit feels, and how to bailout before the CO2 hit is so bad that you don't have the time to switch to OC. Learn to listen to your body and what it's trying to tell you.

A common mistake is to accept gurgling noises coming from your hoses caused by a mouthpiece that lets a bit of water in. If this occurs, do not go head down and breath in - this has killed divers in the past, and continues to do so.
Never get far enough away from breathable air that the bailout gas you are carrying won't get you back. This is a pain in the ### since you are now carrying lots of gas and heavy tanks that you will hopefully never need, but if you need them and don't have them you will die.

I do about a hundred trimix dives a year with my rebreathers using very little money for gas and am having a great time of it.

Michael

 

[The Chairman]

But is the risk worth the reward?

You have the right attitude when it comes to diving them. The divers that aren't crapping in their suits are the ones who take shortcuts, blow off failures and are more prone to die. As soon as I lose my fear of rebreathers will be the day I need to stop diving them

 

[ccrprospect]

Hello

I am a qualified tec diver (up to normoxic trimix range) and was recently thinking of making the switch to CCR. After a try dive and reading a bit about rebreathers, I decided to sign up for a MOD 1 class.

Subsequent to my registration, I read everything I could find online about rebreathers. I ordered and read Jill Heinrith's book on the topic, and then read the manual for the unit I will do the course on. I was shocked by the amount of statements along the lines of "rebreathers can kill you without warning", "you should talk with your family about your decision to dive on rebreathers", and Heinrith's "big sister" warnings interspersed throughout her book. These are not the standard waiver of liability clauses you encounter in scuba - these are real warnings.

I read about the limitations common to all units, and that even though the vast majority of rebreather accidents can be attributed to diver error/carelessness, (a) oxygen sensors are not necessarily the most reliable piece of technology and are implicated in "unexplained" diver deaths and (b) CO2 breakthrough can occur despite proper scrubber packing and can render you unconscious without warning. I read about instructor trainers dying.

I was tremendously excited about that class and I am still sort of interested, but now with GREAT trepidation. I know there is risk in everything in life, but do CCRs simply pose unacceptable risk? I am doing this for fun - I do not NEED a rebreather. I wanted to take the course to save on helium costs, enable longer bottom times, . Is the risk worth the reward?

Sounds like you know the answer already. The costs and risks of CCR are not worth it (imo) unless the type of diving you are doing would be more risky/expensive without it.

Check this out (if you haven't already), especially Pt.6!:
http://www.haynesmarine.co.uk/images/stories/A Survival Guide To Rebreather Diving Nov 2011.pdf

Thanks Pandora. This is actually one of the articles I read prior to making this post. Where I differ respectfully is that very few divers actually NEED rebreathers. The vast majority are doing it for fun - not too different from buying a racing motor bike...

 

[broncobowsher]

Risk? Yes but I don't see it much different than any other technical dive. There are potential problems, but it also has potential benefits. The rebreathers and training have improved over the years. Finding a good instructor is important. Not just the local guy that has owned his first rebreather for 6 months and just got qualified to teach on it, but find someone who has a good reputation and has been diving various rebreathers for many years. You are going to be learning all about rebreathers besides just the one you are getting.

Are they worth it, potentially. They really only turn economical once you start adding Helium to the dives. But you really need to dive it all the time to stay current on it. It isn't something to pull out of storage twice a year when you are going to go do a deep dive. They do have benefits in a lot of dives even if they are not the best choice all the time. Quick example, this past year I did some recreational dives on the U352 with some friends who were all open circuit. I could have picked up an AL80 and dove just like they did. I took the rebreather and didn't worry about air consumption. I dropped down first, hung around, let everyone else rush the anchor line. I found it so much more enjoyable. Logistically it was a bit of a pain, getting sorb and O2 lined up and traveling with it. But it wasn't that big of a pain. Very much worth it.
Later in Truk, completely worth it. Some of those dives simply could not have been done on open circuit. There was not enough Helium on the island that week. There was enough for rebreathers, but not enough for open circuit. Even if there was enough, I don't know anyone who could afford it. He is getting expensive.

 

[kensuf]

Thanks Pandora. This is actually one of the articles I read prior to making this post. Where I differ respectfully is that very few divers actually NEED rebreathers. The vast majority are doing it for fun - not too different from buying a racing motor bike...

Statistically, CCR divers have a significantly higher incident rate per dive compared to OC divers. I also bet if someone were to look at the dives that CCR divers conduct regularly, they will see that those dives themselves entail a significantly higher element of risk (deeper, longer), which may contribute to the statistics.

Can a CCR kill you? Yup. OC can also kill you. So can bathing, believe it or not, several people drown in their bathtub every year.

Can you manage the increased risk of diving a CCR? Sure, proper training, having a deep respect for the machine, and being completely aware can help manage those risks.

Is the increased risk worth the reward? That's something you have to answer for yourself.

 

[AfterDark]

Rebreathers are IMO tools not yet ready for recreational use. Not a popular opinion I know.

If a professional or wannabe professional underwater photog/vidtog needs to dive to 400' to pursue their profession and are willing to accept the risks of CCR that is different than a diver that wants to dive all day. IMO that isn't worth the cost and the risk. I can also see why cave divers embrace CCRs. I think that is a logical and safer choice than OC for cave diving. Cave divers are also more likely to have the self-discipline required of CCRs. The same of wreck divers. I'm pretty sure if I were 18 years old today I'd be trying to find a way to dive a CCR and own one. I was reckless at eighteen.