CORA II rebreather test dive

Recently we had a presentation and test dive of the new rebreather developed by Seaway, called CORA II. Although it was only a short demo and pool dive, some clear differences between the Seaway rebreather and the Dräger rebreather (Dolphin) became apparent. But first some pics (courtesy of M. Bartz):



Adjusting OP valve on exhalation side of counterlung. Since the counterlungs are designed to sit on top of he diver's shoulders (OTS-style ;-) they offer considerably more breathing comfort than the (smaller) bags of a Dolphin which are crammed into a box that the diver carries on his/her back.



Always lovely to dive in the pool... and so meditative! We dived a 80% premix all the way down to the max. depth of 5 (five!) meters at the very deepest tile of the pool's floor. Here you see us recovering on a safety stop at 4,2 meters... The systems were (virtually) silent, but of course I could not resist the temptation to roll around in all kinds of positions to try out the unit's breathing behaviour. Of course the bypass will fill up the counterlung as soon as you roll on your back, but thanks to the lower pressure gradient there were no noticeable "monkey cheek effects".



As you can clearly see on here, the loop is very short, similar to those known from chest-mounted systems (think: LAR series, Oxylon) which is of course a very nice feature both in terms of "lung butter accumulation" (which does not happen noticeably, it all drains right down into the counterlungs) and also, it makes it virtually impossible to lose the DSV - on maximum extent, it hangs in front of your face, at avout eyebrow level. Of course, if you have decided to bail out, this might be a nuisance...



Just hanging out...

So here is my list of items where Seaway has the edge over Dräger:

• stainless steel container for absorber unit and cmf valve
(Dolphin: case is prone to cracking)
• short "OTS" loop, smooth one-hand-operable DSV
(Dolphin: long loop, DSV harder to open/close)
• manual add-on valve on counterlung as standard
(Dolphin: not offered on basic configuration)
• modular design, fits (almost) any jacket and (almost) any tank dimensions
(Dolphin: comes with jacket, only two tank sizes)
• solid and balanced mounting of tanks on either side
(Dolphin: premix below box, bail-out side-mounted in cordura pocket)
• easy handling +maintenance of absorber unit, high capacity, seamless capacity adjustment
(Dolphin: awww, none of this...)
• easy connection of counterlung unit to the rest of the RB; just snap it on
(Dolphin: so many parts, so many screws...)
• 32, 40, 50, 60 and 80 % valve come with basic configuration
(Dolphin: no 80%, only one or two valves in basic config)
• reasonable pricing, cheap and standardized spare parts
(Dolphin: awww, NOT so again...)
• easy to upgrade to SCR II (two gases, two cmf valves, switch during dive), mCCR and eCCR: simply exchange the "head"

I am looking forward to getting my own unit asap, and expect it to replace the Dolphin in the German research diving with rebreathers.