Thoughts about the ray...

canuckdiver

Ok guys, I asked this of somebody and would also like to get some input from the rest of the great minds we have around here...

"My thoughts on the ray was that initially, I like the design of the unit, and for my introduction to rebreathers, it is appealing for recreational depths and short run times, being a small compact unit. It is a relatively inexpensive, commecially available unit, and there are standardized courses available to tech me how to dive the unit.

It also seems that it would lend itself well to a homebuilder. The vertically mounted scrubber would seem to be easy to mount a pair of tanks on either side, KISS like, for dil and O2. The scrubber could be extended in length to add more duration, although that would increase the WOB on the unit. Provision is already built in to the unit for adding PPO2 monitoring. I think I would however, change the ADV/dosage device to the dolphin unit, simply because the dolphin unit uses a normal "tilt valve" and then an additional port for the constant bleed, rather than a "leaky valve" arrangement."

So what is everybody's opinion about getting one of these units, learning how to dive it as an SCR at first, and then either using the parts from it to finish my IDA-71 project, or even using the unit as the basis for a home-built (short duration, shallow depth) CCR?

let the bashing begin! LOL

schford

Biggest thing about it I don't like is its a PITA cleaning it, cleaning CLs etc...Also I believe the location for a sensor is in a very bad position.

Stuart

canuckdiver

Good point, I had been looking at that myself. the bottom of the scrubber seems like it would be a spot that is susceptible to getting water on the sensor, and things hitting the cable.

Might be a good idea to put something like an oxy-2 in the inhale hose?

Scuba_Vixen

As you know, I'm sorta partial to the Dolphin. Especially as a conversion project.

There have already been a lot of ccr dolphins done and the R&D has already been done, and parts available, for those of us doing them now.

It's just not that much bigger than a Ray, and seems to lend itself to conversion much better. Probably why the ratio of dolphin to ray conversions is so one sided.

I'd have to think twice, and pass on the idea of adding an Oxy2, or anything else that sticks up so far in such a vulnerable placement. It wouldn't take much to cause major problems if you whack it into something. Even in open water, just looking under a ledge could impact it. Don't even think "wreck" dive.


Just my thoughts, as I have a conversion in process.


Darlene

caveseeker7

Both Darlene and Stuart make good points.
The Ray is very limiting, the aftermarket for it is likewise very limited.
I wouldn't want to take that scrubber any deeper than its rating,
much less on a CCR that doesn't vent quite a bit of its gasses.

The one person I know who dives one, strictly recreational, is happy
with it. She was in my PRISM class last year, so that maybe is a hint
on what to do when you've 'outgrown' it: Get a CCR.

Better yet, get one from the beginning.
I honestly believe that the Sport Kiss is a feasble alternative to any
cmf SCR, and consider what you save in buying 2 units and trainng
for them ... makes up for some of the price difference.
Ease of maintainance is better than the Ray, and it's so much more
capable.

__________________
Cheers
Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible
to pick up a turd by the clean end.'!"

canuckdiver

good points guys.

Darlene- I agree that the oxy-2 would also seem to be a bad placement for anything as fragile as it is. Another alternative that I have been playing with in my mind (it's more like an etch-a-sketch), is to work out a way to put anothe p-connector into the top cover of the scrubber canister. It looks like there wouldnot be much room though, due to the limited diameter of the canister. Possibly somebody with more hands-on experience with one could comment?

Stefan- I agree that the sport KISS is a far more capable unit, but it is also well over twice the price, and for my immediate purposes (within recreational limits), The ray seems to be able to do everything that I want it to do. I'm interested in your comments about the scrubber though, why would you feel that depth, rather than duration would be the limiting factor? Is it because of the axial design?

Keep in mind guys that I think I may have been a bit misleading in my inital post. The purpose of me buying a ray is not as a basis for a home-build CCR, the purpose is to get a fairly simple unit to use for non-decompression recreational dives, and to gain experience with the procedures involved in making the switch from open circut to rebreather diving.

Scuba_Vixen

I think what everyone is trying to say is that for anything you want to do with a Ray, you can do it better/easier/more conservatively, with a Dolphin (and even do more with a dolphin), and if you shop around, it'll be about the same cost as the Ray.
The other aspect is that if you get a yen for something more later on, you'll get more for the dolphin.

Darlene

caveseeker7

I was referring to the small size and fairly short rating (70 min CE) that the Ray has.
That in and by itself should make the scrubber less than ideal for deep (trimix) diving.

Look at the dfference between the Inspiration (5.4 lbs absorbant) and Evolution (5 lbs absorbant).
That 0.4 lbs less knocked a full third of the duraton during testing !
Now consider the Ray starts out at just over half that duration, when quite some of the gas is vented.
And was never tested or designed to be taken past 40 msw ... just doesn't appeal to me to try.

It's not unique to axial designs, SMI and Carleton tested a smaller version of the PRISM's radial scrubber.
About 1/3 less in size, it worked well at shallow depths in temperate waters.
Don't remember the numbers, but it failed when tested in Canada for cold water and depth.
Duration was limited to about an hour and the project was canned.

__________________
Cheers
Stefan



"Political Correctness is a doctrine, fostered by a delusional, illogical minority,
and rabidly promoted by an unscrupulous mainstream media,
which holds forth the proposition that it is entirely possible
to pick up a turd by the clean end.'!"

nl_carey

If you're buying one just to 'get used' to rebreathers - don't bother. You aren't gaining too much, and you're compromising the ease of use of scuba. Also, all you're getting experience on is packing a scrubber you likely won't be using in CCR, some pos/neg tests you will need to change if you get another unit, and a range of unit-specific things that won't cross over well. Not to mention having to deal with the hassle of SCR dive planning, that you won't use in practiceas it's not PO2 based, and the only real crossover items are breathing from a unit that has a relatively stable gas level (I found the dolphin changes a little in bouyancy due to the OPV, despite what others think), less bubbles, and getting jealous of your OC buddies as tghey jump in the water with nary a thought to their gear.
If cost is really your primary driver, I'd join the chorus of buying a Dolphin instead. Much better unit, much much more capable of flexible diving, but I was pretty dissapointed overall with it - for pretty much the reasons stated above.
Then I got a Sport KISS. Worth every penny, and you simply can't appreciate how much easier the unit is to use and maintain than a Dolphin until you've used one.

Bubble Boy

Hi Guys,

I own and dive a Drager Ray regularly. I'd have to say the follwoing given the comments made:
* Don't buy a Ray if you want to do a lot of deep diving - the scrubber can't cope past an effective tech diving depth (say around 40msw)
* Don't listen to anybody whop tells you it's hard to clean, they're pretty easy to clean and use
* Decide wether you want something to start Rebreather diving with or if you want a CCR
* If you want to make a homebuild KISS type conversion then buy a bloody KISS. by the time you have bought a Dolphin done the conversion and moved on you will have spent the money for a KISS. And Rays have some great bits for homebuilds, but the whole unit is very hard to convert in it's entirity. And expensive for just bits.

End of the day if you want a shallow water unit for Nitrox diving that extends your gas in a mechanical simple way and is easy to dive then buy Drager Ray. They are cheap and competent in shallow water to say around 25 msw.

If you want something to take you to 45 msw plus and make Trimix diving cheap then a Drager Ray is NOT the unit to consider. But remeber that big expensive CCR is going to be a pig to dive in 3- 8 msw of water on a saw tooth profile on reefs.

Let the flaming begin............