Sunnto RGBM, what is up with that?

jluttichau · January 5th, 2006, 02:13 AM

Hi,

I've been wondering about this Suunto RGBM thats in the Vyper and Vytec. When I see guys on the shotline comming up from 45m 30min dives and going streight up to around 12 - 18m and starting deco there and doing most of it at 3 and 6m on O2.
It seems like a haldanian model to me. When i run the same dive through GAP, the deco schedule is very different from what I've seen the Suunto computers produce?

Any explanations?

Cheers
Jonas

StSomewhere · January 5th, 2006, 02:24 AM

Quote: (Originally Posted by jluttichau)

I've been wondering about this Suunto RGBM thats in the Vyper and Vytec. When I see guys on the shotline comming up from 45m 30min dives and going streight up to around 12 - 18m and starting deco there and doing most of it at 3 and 6m on O2.
It seems like a haldanian model to me. When i run the same dive through GAP, the deco schedule is very different from what I've seen the Suunto computers produce?

BRW posted online a couple years ago that it was a "modified RGBM". I think its Buhlmann with some adjustments to make it seem RGBM-like. The Vytec is an awesome bottom timer though, just very expensive.

aki · January 5th, 2006, 02:31 AM

From the Vyper manual:

6.2. REDUCED GRADIENT BUBBLE MODEL, SUUNTO RGBM

The Reduced Gradient Bubble Model (RGBM) is a modern algorithm for tracking both dissolved and free gas in the tissues of divers performing a wide variety of maneuvers. Unlike the classical Haldane models, the RGBM can address a number of circumstances outside the range of just dissolved gas models by:

• monitoring continuous multiday diving
• tracking closely spaced repetitive diving
• accounting for diving deeper than previous dive
• regulating rapid ascents with high degrees of Doppler bubble formation
• incorporating consistency with real physical laws for gas kinetics
• taking a modern approach to a difficult problem.

The SUUNTO RGBM algorithm is developed in co-operation with SUUNTO
and Bruce R. Wienke. It is based both on laboratory experiments and diving
data (for example DAN's dive data).

--
Aki

jluttichau · January 5th, 2006, 01:14 PM

Quote: (Originally Posted by StSomewhere)

BRW posted online a couple years ago that it was a "modified RGBM". I think its Buhlmann with some adjustments to make it seem RGBM-like. The Vytec is an awesome bottom timer though, just very expensive.

Do you know where he posted that? Maybe a link?

Cheers
Jonas

Marcin Kaluza · January 5th, 2006, 03:01 PM

Quote: (Originally Posted by jluttichau)

Any explanations?

SUUNTO RGBM is a neo-haldanean model (fold-up or something like it) that's supposed to mimic RGBM profiles. Ease of implementation was the reason i suppose. Some other computers (explorer?) use fully blown RGBM.
BTW I've read on plongeur.com that that's exactly the case with VR3 and VPM-B. Personally I wouldn't be surprised as VPM-B in its original form due to the iterative nature of the algorithm and various hacks would be very difficult to implement in a "computer". Anyhow I'm not sure if that's the case with VR3 and would be grateful if someone in the know could comment on that.

jluttichau · January 5th, 2006, 03:42 PM

Quote: (Originally Posted by Marcin Kaluza)

SUUNTO RGBM is a neo-haldanean model (fold-up or something like it) that's supposed to mimic RGBM profiles. Ease of implementation was the reason i suppose.

I would like it if you have a source where I can read about this?

Cheers
Jonas

Joe Hesketh · January 5th, 2006, 04:04 PM

Quote: (Originally Posted by jluttichau)

I would like it if you have a source where I can read about this?

Cheers
Jonas

In this, it's described as:

Quote: (Originally Posted by Bruce Wienke)

[a] modified RGBM recreational algorithm (Haldane imbedded with bubble reduction factors limiting reverse profile, repetitive, and multiday diving)...

As I see it, it's essentially a marketing tool for Suunto (though they're not the only ones). RGBM is the latest thinking in deco modelling, so by paying Bruce to waive a magic wand over their product, they can lay some claim to having a state of the art PDC, which is presumably good for sales. It's a go faster stripe, and nothing really to do with an RGBM model (especially in relation to deeper stops, etc.).

Then again, I am a cynical b*stard. :D

Joe

Spectre · January 5th, 2006, 04:34 PM

Let me just show the last dive I did with my Stinger in dive mode:

32 minutes at an average depth of 100 feet. Suunto wanted 18 minutes.
1 minute from 93 to 70. 5 ft/min from 70 to 50. 3 ft/min from 50-30 [2, 2, 2, 3, 3].

Suunto wanted 15 minutes when I reached 30. Did another 3 minutes at 30, then 12 at 20. Suunto wanted another 8 minutes, and my buddy was -definitely- not pleased with me.

For 32 minutes @ 100 on air, I did: 2, 2, 2, 3, 6, 12 then 5 minutes to the surface, tied my suunto onto my spool, tossed it overboard, and switched it over to gauge once it cleared.

***techadmin*** · January 5th, 2006, 04:37 PM

It is a marketing tool - I gave the Suunto rep a hard time about it once.

The only thing RGBM like about it is that it penalises you far more than the original for overly fast ascents so as to mimic the formation of bubbles as per pseudo RGBM.

Weinke okd them using SUUNTO RGBM as a name - no doubt in exchange for some cash!

As has been said the only current true RGBM publiclye available is the HS Explorer.

Although it really should not bother DIR divers as the SUUNTO would be used in guage mode any way!

Mark Chase · January 5th, 2006, 05:21 PM

Quote: (Originally Posted by jluttichau)

Hi,

I've been wondering about this Suunto RGBM thats in the Vyper and Vytec. When I see guys on the shotline comming up from 45m 30min dives and going streight up to around 12 - 18m and starting deco there and doing most of it at 3 and 6m on O2.
It seems like a haldanian model to me. When i run the same dive through GAP, the deco schedule is very different from what I've seen the Suunto computers produce?

Any explanations?

Cheers
Jonas

Yes

Sunnto's RGBM profiles are to RGBM what a Pork pie is to a barmitsva menu

Why the makers of RGBM allowed Suunto to use their name in association with the Viper Vytec etc I have no idea.

However the thing with the Vytec is the ultra slow ascent rates promoted by the unit. Its the equivalent of the 1min in 3m stop principle of doing a 3m/min ascent. So its a combination of the ascent rates and the stops that make it work.

I used a Vytec to do some deepish dives on air back gas to 70m and on three gas using light trimix on the bottom and two deco mix and I got out OK but as per usual I was doing my 3m/min ascent voodoo.

Mainly I would use deco planner to run tables and keep the Vytec as backup. Running 20/80GF it would clear the 6m stop at about the same time as the tables on a square profile dive. However it was a crap deco computer as if you didn't ascend to the stop depths it wouldn't credit you for any stops added to the ascent but it would penalize you.

On some dives i would leave bottom with 30mins of deco and reach 6m 20mins later still showing 30mins of deco.

I had to bend it more than once.

ATB

Mark Chase

January 5th, 2006, 02:13 AM	#1 (permalink)
jluttichau(Offline) Custom User Title Join Date: Nov 2005 Location: Denmark Posts: 437	Sunnto RGBM, what is up with that? Hi, I've been wondering about this Suunto RGBM thats in the Vyper and Vytec. When I see guys on the shotline comming up from 45m 30min dives and going streight up to around 12 - 18m and starting deco there and doing most of it at 3 and 6m on O2. It seems like a haldanian model to me. When i run the same dive through GAP, the deco schedule is very different from what I've seen the Suunto computers produce? Any explanations? Cheers Jonas

January 5th, 2006, 02:24 AM	#2 (permalink)
StSomewhere(Offline) New Member Join Date: Nov 2005 Location: Far from deep water Posts: 43	Quote: (Originally Posted by jluttichau) I've been wondering about this Suunto RGBM thats in the Vyper and Vytec. When I see guys on the shotline comming up from 45m 30min dives and going streight up to around 12 - 18m and starting deco there and doing most of it at 3 and 6m on O2. It seems like a haldanian model to me. When i run the same dive through GAP, the deco schedule is very different from what I've seen the Suunto computers produce? BRW posted online a couple years ago that it was a "modified RGBM". I think its Buhlmann with some adjustments to make it seem RGBM-like. The Vytec is an awesome bottom timer though, just very expensive. __________________ I gotta go where its warm...

January 5th, 2006, 03:01 PM	#5 (permalink)
Marcin Kaluza(Offline) New Member Join Date: Dec 2005 Location: UK, Bracknell Posts: 30	Quote: (Originally Posted by jluttichau) Any explanations? SUUNTO RGBM is a neo-haldanean model (fold-up or something like it) that's supposed to mimic RGBM profiles. Ease of implementation was the reason i suppose. Some other computers (explorer?) use fully blown RGBM. BTW I've read on plongeur.com that that's exactly the case with VR3 and VPM-B. Personally I wouldn't be surprised as VPM-B in its original form due to the iterative nature of the algorithm and various hacks would be very difficult to implement in a "computer". Anyhow I'm not sure if that's the case with VR3 and would be grateful if someone in the know could comment on that. __________________ Marcin HLPlanner - free VPM-B based decompression software

January 5th, 2006, 02:31 AM	#3 (permalink)
aki(Offline) New Member Join Date: Nov 2005 Location: Stockholm, Sweden Posts: 63	From the Vyper manual: 6.2. REDUCED GRADIENT BUBBLE MODEL, SUUNTO RGBM The Reduced Gradient Bubble Model (RGBM) is a modern algorithm for tracking both dissolved and free gas in the tissues of divers performing a wide variety of maneuvers. Unlike the classical Haldane models, the RGBM can address a number of circumstances outside the range of just dissolved gas models by: • monitoring continuous multiday diving • tracking closely spaced repetitive diving • accounting for diving deeper than previous dive • regulating rapid ascents with high degrees of Doppler bubble formation • incorporating consistency with real physical laws for gas kinetics • taking a modern approach to a difficult problem. The SUUNTO RGBM algorithm is developed in co-operation with SUUNTO and Bruce R. Wienke. It is based both on laboratory experiments and diving data (for example DAN's dive data). -- Aki

January 5th, 2006, 01:14 PM	#4 (permalink)
jluttichau(Offline) Custom User Title Join Date: Nov 2005 Location: Denmark Posts: 437	Quote: (Originally Posted by StSomewhere) BRW posted online a couple years ago that it was a "modified RGBM". I think its Buhlmann with some adjustments to make it seem RGBM-like. The Vytec is an awesome bottom timer though, just very expensive. Do you know where he posted that? Maybe a link? Cheers Jonas

January 5th, 2006, 03:42 PM	#6 (permalink)
jluttichau(Offline) Custom User Title Join Date: Nov 2005 Location: Denmark Posts: 437	Quote: (Originally Posted by Marcin Kaluza) SUUNTO RGBM is a neo-haldanean model (fold-up or something like it) that's supposed to mimic RGBM profiles. Ease of implementation was the reason i suppose. I would like it if you have a source where I can read about this? Cheers Jonas

January 5th, 2006, 04:04 PM	#7 (permalink)
Joe Hesketh(Offline) New Member Join Date: Nov 2005 Location: London, UK Posts: 657	Quote: (Originally Posted by jluttichau) I would like it if you have a source where I can read about this? Cheers Jonas In this, it's described as: Quote: (Originally Posted by Bruce Wienke) [a] modified RGBM recreational algorithm (Haldane imbedded with bubble reduction factors limiting reverse profile, repetitive, and multiday diving)... As I see it, it's essentially a marketing tool for Suunto (though they're not the only ones). RGBM is the latest thinking in deco modelling, so by paying Bruce to waive a magic wand over their product, they can lay some claim to having a state of the art PDC, which is presumably good for sales. It's a go faster stripe, and nothing really to do with an RGBM model (especially in relation to deeper stops, etc.). Then again, I am a cynical b*stard. :D Joe

January 5th, 2006, 04:37 PM	#9 (permalink)
*techadmin*(Offline) Administrator Join Date: Nov 2005 Location: Data Center Posts: 214	It is a marketing tool - I gave the Suunto rep a hard time about it once. The only thing RGBM like about it is that it penalises you far more than the original for overly fast ascents so as to mimic the formation of bubbles as per pseudo RGBM. Weinke okd them using SUUNTO RGBM as a name - no doubt in exchange for some cash! As has been said the only current true RGBM publiclye available is the HS Explorer. Although it really should not bother DIR divers as the SUUNTO would be used in guage mode any way!

January 5th, 2006, 05:21 PM	#10 (permalink)
Mark Chase(Offline) New Member Join Date: Nov 2005 Location: Kent England Posts: 905	Quote: (Originally Posted by jluttichau) Hi, I've been wondering about this Suunto RGBM thats in the Vyper and Vytec. When I see guys on the shotline comming up from 45m 30min dives and going streight up to around 12 - 18m and starting deco there and doing most of it at 3 and 6m on O2. It seems like a haldanian model to me. When i run the same dive through GAP, the deco schedule is very different from what I've seen the Suunto computers produce? Any explanations? Cheers Jonas Yes Sunnto's RGBM profiles are to RGBM what a Pork pie is to a barmitsva menu Why the makers of RGBM allowed Suunto to use their name in association with the Viper Vytec etc I have no idea. However the thing with the Vytec is the ultra slow ascent rates promoted by the unit. Its the equivalent of the 1min in 3m stop principle of doing a 3m/min ascent. So its a combination of the ascent rates and the stops that make it work. I used a Vytec to do some deepish dives on air back gas to 70m and on three gas using light trimix on the bottom and two deco mix and I got out OK but as per usual I was doing my 3m/min ascent voodoo. Mainly I would use deco planner to run tables and keep the Vytec as backup. Running 20/80GF it would clear the 6m stop at about the same time as the tables on a square profile dive. However it was a crap deco computer as if you didn't ascend to the stop depths it wouldn't credit you for any stops added to the ascent but it would penalize you. On some dives i would leave bottom with 30mins of deco and reach 6m 20mins later still showing 30mins of deco. I had to bend it more than once. ATB Mark Chase