Computer Choice for Rebeather Diving

[michaelr]

anyone here uses deco. computers for diving on CCR ?

is VR3 considered to be the "best" ?

appreciate the feedback.


Michael

 

[dugandiving]

I owned a Vr3 for two years, but have recently sold it and replaced it with a HS Explorer. The Vr3 was amazingly solidly built, and many people swear by them. However, for myself I found several things about it incredibly irritating. The first and foremost was, what seemed to me, its extreme conservatism. Even on its most liberal setting it was still way more conservative than the Nexus. Some people find this conservatism reassuring, personally I found bouncing around doing deco I knew was unnecessary rather aggravating. The second thing I did not like about the Vr3 was that it forced you to do deep stops, but then penalised you very heavily with extra deco time for doing them. It was not possible to turn the deep stops off. I used the Vr3 on some very deep dives, over 100 metres, and it usually performed flawlessly. However, for the way I like to dive, its shortcomings outweighted its advantages. Doubtless many people will disagree with me, but my dislike of these characteriztics in the end forced me to find a computer that better fitted my requirements.

 

[caveseeker7]

The VR3 is a good computer, and likely the widest used one with CCRs. Like Dugan, I prefer the Explorer too. It does RGBM (if you want it to) and has the best display. The Nexus isn't exactly known to be a conservative computer, and OC it tested borderline ... .

When I saw your post I thought someone asked the question in general. After two "dry days" on the board I might as well. If I forget one, feel free to add it. The subject keeps coming up.

For CCRs (constant PO2 calculation)
HS Explorer - RGBM, single cell O2-integration, Nitrox/Trimix/Heliox
Delta P VR3 - microbubbles, single cell O2-integration, Nitrox/Trimix/Heliox
Delta P VR2 - microbubbles, single cell O2-integration, Nitrox
Abyss Explorer - microbubbles, Nitrox/Trimix/Heliox
Cochran Gemini - Nitrox
Buddy Nexus - Nitrox

For SCRs (more or less FO2 calculation)
HS Explorer, Delta P VR2 and VR3 work with SCRs
Uwatec ZO2/Oxy2 - dual cell O2-integration, Nitrox
The "more or less" makes the O2-integration necessary on CMF SCRs.

Hope I got them all.

Addited: Both HSE and DeltaP have their respective manuals online as .pdf downloads. Have a look at them. Also a link to the RGBM website:
http://www.hs-eng.com/
http://www.vr3.co.uk/index.shtml
http://www.rgbmdiving.com/

 

[fins wake]

... to Stefan's (as usual) excellent post you might find the following comparison useful:
http://www.hs-eng.com/Comparison.htm
(Please note that this is HS own comparison [for bias purposes], however at first glance it seems fair and comprehensive.)

I've never used the HS Explorer and theoretical comparisons can't compare with practical experience. Stefan's and Geoffrey's comments are therefore duly noted.

 

[caveseeker7]

Am I paying you for this?

The other day there was a good thread in the computer section on the Explorer and RGBM, Padiscubapro made some excellent posts:
http://www.scubaboard.com/t30941/scd3e7f281da5698395fc318d3779171d.html
And on my way to get the adress I read the "buttons stuck" thead. Another nice solution HS engineered into the Explorer: The two buttons slide up and down in tubes. Won't crack it open, but I assume it's a magnetic switch. As it is open on the bottom you can push back from there if it ever gets stuck. It's the little things in life ...

 

[padiscubapro]

caveseeker7 once bubbled...
The VR3 is a good computer, and likely the widest used one with CCRs. Like Dugan, I prefer the Explorer too. It does RGBM (if you want it to) and has the best display. The Nexus isn't exactly known to be a conservative computer, and OC it tested borderline ... .

When I saw your post I thought someone asked the question in general. After two "dry days" on the board I might as well. If I forget one, feel free to add it. The subject keeps coming up.

For CCRs (constant PO2 calculation)
HS Explorer - RGBM, single cell O2-integration, Nitrox/Trimix/Heliox
Delta P VR3 - microbubbles, single cell O2-integration, Nitrox/Trimix/Heliox
Delta P VR2 - microbubbles, single cell O2-integration, Nitrox
Abyss Explorer - microbubbles, Nitrox/Trimix/Heliox
Cochran Gemini - Nitrox
Buddy Nexus - Nitrox

For SCRs (more or less FO2 calculation)
HS Explorer, Delta P VR2 and VR3 work with SCRs
Uwatec ZO2/Oxy2 - dual cell O2-integration, Nitrox
The "more or less" makes the O2-integration necessary on CMF SCRs.

Hope I got them all.

Addited: Both HSE and DeltaP have their respective manuals online as .pdf downloads. Have a look at them. Also a link to the RGBM website:
http://www.hs-eng.com/
http://www.vr3.co.uk/index.shtml
http://www.rgbmdiving.com/

you forgot the cochran comander constant po2.. they have a version that allows 2 po2 settings.. nitorgen only based.. no cell integration, but the best damn logging computer out there.. I use mine to log my dives(when I need to analyze them), it does 550 hours at 1 second samples(I was given mine as a test unit - so its logging was better than was available at the time), the normal unit does 550 hours at 5 second samples (at least last time I checked)..

The abyss explorer can be upgraded to RGBM for a nominal fee by sending it to Hydrospace, Gene will also let you trade it in for a cell integrated version (brand new) with all the latest software for $300...

Gene is working on some minor updates to the RGBM code, that should be released sometime in the future.. RGBM is overly conservative on shallow (less than 110 fsw) short dives, with some new info from B.W. it will be made a bit more libral, and the most conservative RGBM setting is going to be made a bit more conservative for people doing real extreme dives, the shallow stops are going to be padded (30,20,10) probably an additional 10% each..

 

[caveseeker7]

Ooops, sorry Cochran & Comander users. At least I had the Gemini in there ... .

Aside from the RGBM website some good info on RGBM, as well as its implementations has been printed in Advanced Divers Magazine. The current issue (#14) includes an article by Wienke and O'Leary comparing RGBM to ZHL (Haldane), GUE's D-Plan as well as several computers with each other (no deco/multible dives). Good stuff. Best dive mag I know, the only mag I subscribe to. Issues 4,5 & 10 also cover RGBM. Issue 11 the VR3. Halcyon,
K3, Cis-Lunar and Prism were also in there at one point or another.
http://www.advanceddivermagazine.com/
They're planning on publishing Issues 1-12 on CD ROM as PDF files.

 

[blacknet]

Hello,

What about the Nitek-3 and HE models?

Ed

 

[padiscubapro]

blacknet once bubbled...
Hello,

What about the Nitek-3 and HE models?

Ed

waste of money, don't do constant po2.. yu'd have
to run open circuit/scr profiles.

 

[padiscubapro]

fins wake once bubbled...
... to Stefan's (as usual) excellent post you might find the following comparison useful:
http://www.hs-eng.com/Comparison.htm
(Please note that this is HS own comparison [for bias purposes], however at first glance it seems fair and comprehensive.)

I've never used the HS Explorer and theoretical comparisons can't compare with practical experience. Stefan's and Geoffrey's comments are therefore duly noted.

Before Gene published his comparison, I joked he had to many "no" entires in the comparison, I believe its a fair assessment, he didn't try and publish a chart that just showed his strengths.. There are also other things that aren't listed that the original VR3 said the explorer didn't do (so of them were only true for the original software release).

The big thing I remembered was being able to reprogram the po2 underwater and choose whatever you felt like, on the first release this was true (no many people ver had it).. Both the VR3 and explorer do it equally well.. but in all cases reprogramming the explorer is considerably easier..

one thing thats handled differently between the VR3 and explorer is how mixes and po2 mode are handled..

ont the vr3 any of the 10 mixes can be po2 or open circuit, the explorer handles it a bit differently for simplicity..

in the non intergated version, all 10 mixes can be open circuit or first 5 po2 second 5 open circuit bailout,
on the integrated version, all 10 can be oc, or 5 ppo2 and 5 oc with the first when in po2 mode can be programmed tio use the cell or use a fixed po2, 4 and 5 are for a fixed po2, the last 5 for oc bailout...

this may seem like a deficiency but it has definate advantages, lets take an example.. I am going to use the computer for a constant po2 dive (the last mixes are oc bail out), I'll program mix 0 with, my diluent and cell set to on (1st 3 (0-2)are all either on or off), then mix 3 I set as the same diluent but with a pre selected setpoint... if I am having tbl with the cell, I can just do a gas switch to the mix thats a fixed po2 and not have to worry about shutting off the cell (and then setting a po2)..

On the vr3 you have to shut off the cell (effects every mix) then manually chose a setpoint, while going through multiple menus...

on the explore the switch is simple hold 2 buttons for 1 second, advance the mix 3 presses then hold the left button for a 3 count to confirm the switch..