Unusual Rebreathers

[NotDeadYet]

Hi Folks,

we tend to live in a very Inspirationcentric world so it's easy to forget that there are other RBs out there. Iwas lucky enough to be part of an expedition where a large number of the less well known rebreathers were used. Just got the pics and made up a gallery and quick review of some units that don't get seen much at Dorry or Stoney.

Rebreatherfest 04

Cheers,

Stuart

[db8us]

Hi Stuart,

nice summary !
About diving a passive SCR during having "Stress" i must say, when you are stressed, you DO NOT LOOK at you instruments.
But you immeditaly realize a missing sound, trust me on that !
And you can hear it even while scootering. On the EDO the sound is not so loud, cause the main plate is not made out of aluminium.
There are now even more copies out in the market. Let´s see what happens.

Trianing is critical on all breathers and can not be done in 3 dives and one weekend.
Some of the RB80-clones are even sold without training....

[KISSer]

Originally Posted by db8us

Hi Stuart,
Trianing is critical on all breathers and can not be done in 3 dives and one weekend.
Some of the RB80-clones are even sold without training....

Could you explain why you think this is such a big issue? I'd rather say "experience is critical on all rebreathers and cannot be gained in 3 dives and one weekend". Training is merely one form of education - there are plenty of others, and it's not necessarily the best or most appropriate means. "Self directed learning" is equally valid and can lead to a more extensive knowledge being gained by the student - training is by definition limited by the trainer.

Sure, it's easy to point at some RB fatalities and blame the training, but that argument's been done to death. If someone gets in without a pre-breathe or fails to check their PO2, then that's not necessarily the training at fault.

I'm not advocating that anyone can strap an RB on their back and jump in, but these days there seems to be a lemming like tendency to rush off to a 'training course' to learn the very basics. I can honestly say that I didn't learn any new factual info on any of my nitrox or mix courses - I'd already done plenty of reading, investigating and thinking to be sure I knew what I was getting into. I did however gain experience, and picked up tips from both the designated instructor and my peers. Similarly I've never done a gas blending course, but can mix a damn sight better than most of the dive shop monkees.

If you come out of a training course thinking you are immediately 'qualified' to do something then that's potentially more dangerous than the person who's done their thinking and worked out how to progress in a safe, conservative manner.

As Rumsfled would say - If you know how much you don't know then you know you don't know it all.

[And]

Originally Posted by KISSer

I can honestly say that I didn't learn any new factual info on any of my nitrox or mix courses - I'd already done plenty of reading, investigating and thinking to be sure I knew what I was getting into.

Yes that perhaps is true, but you had been trained on the use of SCUBA, over the course of many years and many dives, in which case learning nitrox and trimix should really be a 5 minute lesson.

Diving a rebreather surely requires at least as much training as you had when learning SCUBA, more so given the many more failure points and then a comparable time period to gain experience. The trouble is that after 4 or 5 years of using SCUBA and progressing to trimix dives, newly qualified rebreather divers tend to dive shallow for less than a season and then try to do the dives they were doing before, without the experience IMHO.

Surely you cannot compare a rebreather with a trimix course. They are very different.

Andy

[KISSer]

Originally Posted by And

Diving a rebreather surely requires at least as much training as you had when learning SCUBA, more so given the many more failure points and then a comparable time period to gain experience. The trouble is that after 4 or 5 years of using SCUBA and progressing to trimix dives, newly qualified rebreather divers tend to dive shallow for less than a season and then try to do the dives they were doing before, without the experience IMHO.

Surely you cannot compare a rebreather with a trimix course. They are very different.

Andy

Intersting points. IMHO the important thing isn't the number of failure points on an RB, it's the number of failure modes. Hypoxia, hyperoxia, hypercapnia, dodgy cells, flooded loop etc etc etc. Yes, there are more of these than there are on OC, but do you suggest that an RB newbie should experience all of them before venturing deeper?

I don't think you can compare RB eduction to basic diver education either - the diver's in-water skills are all there (though some need to be un-learned or overriden) and the laws of physics are reassuringly similar.

IMVHO the biggest leap with an RB is the constant need to evaluate whether the thing on your back is doing its job, and being alert for any manifestation of technical or physiological symptoms. You can tell someone that in a few seconds, but to learn it you need to become totally familiar with 'service as usual'. Who says how long that takes?

So why do people run off to deep diving with only 10 hours under their belt? Perhaps because they are a 'trained' and 'qualified' RB diver who has been taught all they need to know about RBs, and after all they're just using a different Diluent aren't they???? There seems to be a general rush toward deep mix diving throughtout the diving community as a whole - your statement of '4 or 5 years' bears testament to that. Maybe that's as much a part of the urge to get back there on RBs as the whole depth/experience thing.

[PrettyFishies]

Training is useful from the perspective that you can learn to recognise unit failures and take corrective action. However there really is no way to learn about how physiological symptoms feel and affect you except through experience.

The training courses advocate flushing the loop in the event of physiological symptoms however IMHO this may not be quick enough to get "good" gas flowing round the body.

As KISSER says, it's more dangerous when a diver believes that the cert card then means they are competent. There is a difference between competent and experienced. It takes time to recognise failures and understand how to correct.

I taught myself to dive my RB in controlled conditions and through experience came to learn that not everything critical for survival is actually covered in the courses. A user will learn how to dive a unit but only experience will teach a diver how to recognise correct RB patterns and failure modes.

After later doing a course for interest this was reinforced. Physiological symptoms can hit hard and render it difficult to make decisions. Having surfed the learning curve the hard way and asked TDI to change course content to reflect, divers definitely need to take some responsibility for learning through the experiences of others and not just through some training manual.

Training can lead to a false sense of security through divers believing that the course content will have contained everything they need to know. This can not be possible as there are so many spurious things that can happen with RBs and only experience teaches the diver how to recognise and what action to take.

[db8us]

I do not mean "card issuing", but training...
This means "play around" with the unit and get knowledge from people with more experience.
I am not necessarily talking about "taking a course".
But neither i am thinking of "just selling"...

[NotDeadYet]

Originally Posted by db8us

I do not mean "card issuing", but training...
This means "play around" with the unit and get knowledge from people with more experience.
I am not necessarily talking about "taking a course".
But neither i am thinking of "just selling"...

Hi Michael,

I have to agree. Especially so with this style of RB. It has many features and failure modes that are unique to this style of rebreather and no amount of "general" experience can prepare you. As an example, choosing a gas which is very simple on a closed circuit RB is quite complicated when it comes to the RB80 (et al).

I've never been happy with the idea that you cannot buy a RB without buying the training too -- afterall I can walk into a dive shop and buy as much OC equipment that I like and no-one will ask to see any training record. But I would like to be able to choose to do it with someone that I trust.

A friend was forced into doing a training course on his RB here in the UK to have the instructor teach him to assemble it wrongly. He only found out from diving with a naval diver that he had been taught wrongly.

Personally, I'd much rather learn from diving with a group of people who know what they are doing over the space of weeks, months, years, whatever.

And on the EDO-4 the bellows housing is aluminium, though I can't remember what the scrubber is made from. I find the system hard to relax on, I still think being able to make a quick look at a handset must be easier and more reassuring than listening for the dump. Don't know about the RB80 but on the EDO4 the dump sounds more like a gurgling noise, so what may be the sound of it working properly may also be interpreted as the sound of a problem. Feeling gas injector fire OTOH on the EDO4 is a much more positive sign with this unit as it is unmistakable.

Cheers,

Stuart

[db8us]

Hi Stuart,

we are on the same line about training.
About the Aluminium, i did not mean the housing, but the Plate were the injectors are mounted to...
I can hear my unit inject clearly and venting also.
If it is not venting, it is not injecting.
Only when you descend.
The guy who died, might have heard the injecting since he descended rapidly.
The he ascendes pretty fast too, so gas was dumped.
When he relaxed, he died, since he either paid no attention to the sound or he did not know (which i think was the case)

We train all our divers approx every 6 Months. This includes theory, pool, open water and cave environment.
Of course we can do this, since it is not commercial.... and still i think breathers are killers...

Michael

[Pierre Farrugia]

Hello,

This is from a to be an inspiration breather diver, I prefer to do a course, and learn as much as I can from it and then sit down and try to think about what I learned. I already read a lot about it and also read the manual which seems quite comprehensive. Then Intend to do a lot or shallow work with it until I feel confident with the unit.
About trying to do deep dives with the unit, I think I know the feeling as at a sudden you are doing deep wreck dives than you switch to shallower ones and you know you ahve a tool that can do the bigger one's better!

As it has been said mant times here is practise is the key, on OC we dived it for years, maybe even trained other and now everything is second nature, you don't want to ahve a problem and try to resolve it in an OC mentality!

As I said before I am still only OC and maybe with experience and training I can know if I said something wrong!

Regards

Pierre