Bubble Gradient Model Dive Computer

[O-ring]

The Suunto model ain't RGBM...it is a bastardized version of it cobbled together with some Haldane stuff. Like PSP says...go deco on one and you will know immediately it ain't RGBM..

Bruce's site is up at www.rgbmdiving.com

 

[Charlie99]

O-ring once bubbled...
The Suunto model ain't RGBM...it is a bastardized version of it cobbled together with some Haldane stuff. Bruce's site is up at www.rgbmdiving.com

"bastardized" isn't the term I'd use. "Fudge factors" is a more neutral term. What works, works.

Thanks for the link. This is what that website says: "modified RGBM recreational algorithms (Haldane imbedded with bubble reduction factors limiting reverse profile, repetitive, and multiday diving), as coded into Suunto, Mares, Dacor, ABYSS, HydroSpace, Plexus decometers, lower an already low DCS incidence rate of approximately 1/10,000 or less. "

It does appear that Windows PC based true RGBM deco programs will soon be available.

I look forward to comparing the results of various profiles with calculations done by RGBM, straight Haldane, and Haldane with the gradient factor hack that introduces deep stops.

Charlie

 

[O-ring]

Sorry for my choice of words..

 

[Kettle]

Wow lots of info, a bit too much for a newbie like me. Sounds like they all work, just a matter of personal preference? Thanks for your help.

 

[vicky]

between some algorythms. You can download software like Suunto's SDM, a demo version of GAP, Abyss, V-planner and so on.
What to do with them? You can make lots of simulation, including repetitive dives, reverse profiles, short stops and so on.
You can compare the results between all the programs I listed. In the Abyss, you can switch between RGBM and several versions of their algorithm, in Sunnto SDM you can change computer models (e.g. Solution, Vyper, Vytec), V-planner works on two versions of VPM. In all of them you can change the model to more or less conservative.
If you want to compare the results between the models you can choose "classical" square profiles, and feed all the softwares with the same parameters so you'll be able to see the difference in the deco stops they suggest and so on.

I was surprised, but to me it seems that Suunto's RGBM is not a bluff, or a Haldanian model modified according to things like reverse profiles like some suggest. It seems they have introduced some real RGBM features because results are pretty much similar to what one gets using ABYSS with RGBM.

Anyway, it seems that Suunto computers using "RGBM" tend to be quite conservative and from my point of view it is an excellent feature for a recreational diver. For a techie who the difference between "models" and "conservationism" is translated to perhaps a difference of 70 minutes in deco stops, perhaps he can choose if he wants to go conservative or take the risk and spend less time with shoter deco stops in water using a less conservative algorithm...

 

[padiscubapro]

vicky once bubbled...
between some algorythms. You can download software like Suunto's SDM, a demo version of GAP, Abyss, V-planner and so on.
What to do with them? You can make lots of simulation, including repetitive dives, reverse profiles, short stops and so on.
You can compare the results between all the programs I listed. In the Abyss, you can switch between RGBM and several versions of their algorithm, in Sunnto SDM you can change computer models (e.g. Solution, Vyper, Vytec), V-planner works on two versions of VPM. In all of them you can change the model to more or less conservative.
If you want to compare the results between the models you can choose "classical" square profiles, and feed all the softwares with the same parameters so you'll be able to see the difference in the deco stops they suggest and so on.

I was surprised, but to me it seems that Suunto's RGBM is not a bluff, or a Haldanian model modified according to things like reverse profiles like some suggest. It seems they have introduced some real RGBM features because results are pretty much similar to what one gets using ABYSS with RGBM.

Anyway, it seems that Suunto computers using "RGBM" tend to be quite conservative and from my point of view it is an excellent feature for a recreational diver. For a techie who the difference between "models" and "conservationism" is translated to perhaps a difference of 70 minutes in deco stops, perhaps he can choose if he wants to go conservative or take the risk and spend less time with shoter deco stops in water using a less conservative algorithm...

Don't use the ABYSS RGBM as the yardstick.. Their version of RGBM has so much conservatism added that other than deeper stops its profiles come out quite close to haldane models.. download the explorer simulator from www.hs-eng.com and run some sample square profiles and look at the total TTS for various profiles.. the most liberal RGBM should be compared with a fairly conservative haldane model for the same safety factors.. a fair compairson would be using a CF of 0 (0,1,2 are RGBM) with a CF of probably 5 (cf 3 is an un modified straight buhlman with just a slight conservatism factor added), a cf of 2 I would compare with probably a cf of 9.. if you really want to see useful profiles make sure you do the appropriate gas switches. using a single gas is pretty useless..

a good profile to look at would be a 200fsw (61 m) dive for 30 minutes using a 25%helium mix (20%) oxygen with a switch to 50% at 70-fsw (21m). do it for both oc and cc.. This is a pretty reasonable dive and will quickly show the advantages of RGBM.. (then do the same dives using software like gap and put on GF and see how long the dives get for comparable safety)

 

[JeffMandell]

I'm a little confused by this thread (and some others like it). It seems that the underlying premise to the RGBM computer preference is that other computers are not conservative enough and are, therefore, risky.
I'd like to know if this really makes a difference to recreational divers who rarely stray beyond 100 feet, or is this needed "conservatism" really only an issue in tech dives? I'm not aware of any non-anecdotal data suggesting that non-RGBM computers are causing increased DCS in the casual diving range I'm asking about.

 

[Jai Bar]

for recreational divers too. For example, diving safaries involve several days with lots of repetitive dives, occasionally reverse profiles or a fast ascent (yeah, **** happens Obviously, this forum does not allow new member to swear in their text. Originally I wrote sh*t happens and some magic turned it into a ****. Anyway- sh*t happens ). This is the point where a rec diver needs something that tells him to slow down the pace (at least in my case, rational doesn't work in a Safari, I'm too dumbed/numbed/narked by the dives, fish and N2 =-) ) and this is where a good "conservative" computer may be handy. Yep, everyone teaches you that a diving computer should not replace our minds- but hell- "when is the next time I'll be in a safari in such a wonderful place, and there is so much to see and so little time- let's plunge again, face consequences later... "

 

[jamiei]

Jeff, you seem to have it backwards... tech divers are the ones that want the liberal computers and rec divers are the ones that want the conservative computers... thats what makes each type diver what they are. Rec divers don't push the limits and thus don't need a liberal computer. Tech divers do and do need the advantages a liberal computer gives them.

The questions shouldn't be why would a rec diver want a conservative computer, but rather, why wouldn't a rec diver use a conservative computer? It isn't gonna limit them because they aren't gonna push the limits in the first place.

 

[MonkSeal]

padiscubapro once bubbled... a good profile to look at would be a 200fsw (61 m) dive for 30 minutes using a 25%helium mix (20%) oxygen with a switch to 50% at 70-fsw (21m). do it for both oc and cc.. This is a pretty reasonable dive and will quickly show the advantages of RGBM.. (then do the same dives using software like gap and put on GF and see how long the dives get for comparable safety)

New version of GAP includes full RGBM - you can check latest posts from BRW in "Ask Dr. Deco" forum. Trial version can be downloaded from GAP site - it can show RGMB and ZH profiles in parallel - differences are obvious.