Passive Scr Superiority?

decoweenie

I have to say that is not entire true.

From first-hand experience of diving the XCR (which is a mCCR conversion of the EDO-04, which is a Rebreather-80 clone), the WOB is very nice when you have proper trim.

But yes, if you dive like a seahorse, then the WOB is cr*p.

__________________
"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

- Rebreather World PM

silent running

OK Phi, maybe in one position WOB is acceptable. But any unit that doesn't breathe well in all positions, has poor WOB, IMHO. I don't know about everybody else, but I run through a variety of positions during my dives. I'm heads down during descent, horizontal when swimming, more vertical when stopped looking at something, and sometimes more vertical during ascents. And sometimes, I even wind up spending a little time on my back. And after the crazy positions I have found myself in while getting whipped around by strong currents, I'm glad my unit breathes well in all positions.

And what about at high RMVs on the XCR? Does the bellows have more resistance the harder you breathe?

Marc T

Nice! So we are back on topic from time to time
Im used to dive with my mCCR EDO04 and his positionnal WOB prob, but what a surprise when I could try a military DC55 last year!
Breath like a dream in any usual position because of the position of the CL in the middle of the back.
A civilian system derived from DC55 has been created several years ago, will search for a link

trob09

Interesting. The point of all "this statistical BS" is to do exactly what you are suggesting would happen with your 10,000 dive plan - remove the margin of error and provide real apples-to-apples comparisons.

Further to that point, how can you be sure that all rebreathers get the same 10,000 dives in your plan? A Dolphin may get them all above 100' with no deco obligation and an average dive duration of 40 minutes. A trimix-capable eCCr may get the majority of those dives below 250' with substantial deco obligations and an average dive duration of over 90 minutes. Are these the same dives? Do they carry the same risk?

Without considering these variables through 'statistical BS' you will never get a projectible accident rate.

jmurba

Salut Marc ,

A lot of dc55 will soon be arround cause this rebreather is going to be removed from our Forces and replaced by a similar but better Rebreather based on the same working principle.
So you will certainely be able to get one....
the problem with this rebreather is to get the spares, it is impossible to.
This rebreather is manufactured in Carros near Nice city in the south of our country, but the problem is that the 44 armies in the world that buy this solution buy a couple of hundred units with all the necessary spares to un keep and repair the breather wothout denpending on aqualung they also buy the moulds to make some parts.
Acqualung have therefore no spares to provide us with....

I've had many opportunities to get dc55 units but without at least a couple of spares belows it is not a good idea.

as for the clone , the maker is a good guy named Mr Panetier that is now making units for professionnals red coral divers, i coud find back is tel number if i look for it.

you also have to know that in the french army between every dive of couple of dives the unites are completely undone, cleaned , most of the critical spares are changed (valve butterflies etc...), they are requalified, and given back to the forces.

this one of the reasons of it's relyability

the aim of this rebreather is not to give pleasure to the divers during yars of service , but to be ready to work in any condition the D day witout preparation check without calculations oxymeter or any thing it is there to be breathed strait away to jump down and dive.

but it is a really beautiful machine.

As for those kind of machines i am personnaly sure that they are safer then the ccrs for they don't rely on fragile fuel cell sensors that we all love and fear, but they don't provide us with the same durations they are more semi-opened machines then then real re-breathers....

the dc 55 has a 1/12 ratio where the RB80 have 1/8 ratio(if i rememberr well) if you remove all the necessary pre dive tests, flushes it gived you rather 1/6 ratio, ok it is not to bad but not enough to justify to switch from oc to Rebreather.

I think that those rebreathers can be very efficient for certain kind of dives , for exmple they can easily be twined for cave diving, or they can permit to save botom gas on very square and deep and short dives, but they can't compete a small kiss for sport multi level ccr dives .

regards

jean mi

Marc T

Hi jean -michel nice to read you from time to time
Yes am interested and perhaps some others with a contact with mr Panetier.
On an other forum I said that perhaps the last Rebreather I stay on could be EDO O4 exactly for the reasons you exposed speaking about DC55:Ready to go even if you dont use it since a long time, like OC in fact ( or bicycle ).
Prob of the EDO or RB80 is finally more a weight prob for sport dive ( and old divers ).
If some one built somewhere a light pSCR easily convertible in mCCR it could be a lovely rig to grow old with

jmurba

Hi Marc,
nice to read you also, if fact i think that those Rebreather are at least very interresting, i should give it a try before speaking of them, you have divd both so your opinion is better then mine.
I think that the main problem of those breathers are the belows location and the difficulty of building the mecanical parts.
the dc 55 had a very light and good design, it will be deifficult to make a better one
I am going to ask a ggod friend of mine where and when it will be possible to get the used dc55

regards

jean mi

wookey

not forget to mention, that it is with a twin pscr using the same inner construction than the dc55 that Sylvain Redoutey did his amazing exploration of the Goul de la Tannerie (1200m penetration -209m deep and 21hours long dive) !

O.C.Diver

You certainly have a valid point regarding the difference in average dive risk when comparing different types of units.

My point was to say that if a manufacturer produces 50 rebreathers and 1 user dies on his unit, the fatality rate is 2%. This wouldn't be considered a very safe unit. If we then learn that each unit has an average of 2,000 dives on it (1 death per 100,000 dives), the unit starts to look safer. Finally, we learn that the one death was the result of the user being attacked by a shark, the death becomes pretty meaningless as it relates to the rebreather. My point was that units that have 1 or 2 deaths associated with them probably can not accurately be judged due to such a small sample.

Ted

__________________
Consider this my opinion.......sometimes I'm even right, but remember.........YMMV.

Ted Green
Charter Boat "OC Diver"
http://www.ocdiver.com

jmurba

saluuuuuuuuuutttttttt (hellllllo)

I did not know this, as a matter of fact this is an evidence of the capabilities of those systems.
the question is a fuel cell more fragile or more likely to fail then a double belows system ? (even twined dc55 stype Rebreather).

I could not reply, no body can cause this has not been studied in lab with a scientific approach.

20 hours and 200 m away from surface I really don't kwo what I would prefer 2 x 3 fuel cells or more of 2 double belows ?

I certainely would prefer to stay in front of the fire place to be honest....well
.......

After hundreds of Rebreather dives i still think that my S80s are my best insurance and that my rebreather is always capable of stabbing me in the back....

I would not depend only on 1 or 2 or even 3 rebreathers.....

regards

jean mi