Suunto EON Core? Where did this come from?

[Tom Ahola]

@Tom Ahola
RGBM is not considered a state-of-the-art algorithm and is not favored by any decompression scientists that I am aware of.

This was not a dive algorithm thread but it seems to be a sensitive issue. Yes, the Bühlmann GF is still popular although the RGBM is more advanced. I would not call Bühlmann GF state-of-the-art, just popular with a certain small group of divers. I believe there are not many decompression scientists out there and they tend to favor their own creation. I think the Bühlmann GF is popular for some divers because of two reasons. First, it is so simple it is easy to understand. Second, the current RGBM implementation can be conservative in some cases. The RGBM is based on the same principles as Bühlmann. The difference is that the gradient factors which the diver sets manually are replaced by reduction factors, which are computed scientifically based on everything the diver does during current and previous dives, that might affect the bubbles. This way if the diver does some mistakes, or just certain type of dives, the ascent times will grow to keep him safe. Some divers don't like this.

But enough of algorithms for now in this thread. We can start a new separate discussion about algorithms if needed.

- Tom from Suunto

 

[tbone1004]

This was not a dive algorithm thread but it seems to be a sensitive issue. Yes, the Bühlmann GF is still popular although the RGBM is more advanced. I would not call Bühlmann GF state-of-the-art, just popular with a certain small group of divers. I believe there are not many decompression scientists out there and they tend to favor their own creation. I think the Bühlmann GF is popular for some divers because of two reasons. First, it is so simple it is easy to understand. Second, the current RGBM implementation can be conservative in some cases. The RGBM is based on the same principles as Bühlmann. The difference is that the gradient factors which the diver sets manually are replaced by reduction factors, which are computed scientifically based on everything the diver does during current and previous dives, that might affect the bubbles. This way if the diver does some mistakes, or just certain type of dives, the ascent times will grow to keep him safe. Some divers don't like this.

But enough of algorithms for now in this thread. We can start a new separate discussion about algorithms if needed.

- Tom from Suunto

why do you say the RGBM is more advanced when all of the decompression research says it is not a useful algorithm and puts you at higher risk of getting bent during technical dives? I would hardly say near the entire technical diving community, especially when backed by DAN and the rest of the decompression research is a "certain small group of divers".
Short list of important people, none of which had any involvement in creating Buhlmann, however I will say the sole reason that NAUI still uses RGBM is because Dr. Weinke is on the board of directors so he certainly favors his own creation.
Neal Pollock
@Dr Simon Mitchell
@Duke Dive Medicine
list is obviously much longer, but the first two are doing lots of active research right now and I have yet to see anyone except those from Suunto or NAUI advocate for RGBM.
Is it possible that you are guilty of your own accusation? Working for Suunto has skewed you into believing that the RGBM algorithm is superior to all others as that is the one chosen by Suunto for all of their computers?

RGBM is a bubble model, Buhlmann is a dissolved gas model, they are not based on the same principles....
Algorithms are very important when discussing computers, RGBM is not a smart algorithm to use on technical dives. Does it matter at recreational levels? Not really, but to say that RGBM is more advanced and to say that all of the leading researchers who are promoting ZHL are doing it because they favor their own creation is ludicrous when the guy who created it died 25 years ago

 

[stuartv]

Sorry I was not clear enough. The RGBM algorithm has been validated against Navy dives by Bruce Wienke of Los Alamos National Laboratory. Meaning that the database of a large numer of their dive profiles and the outcome has been checked computationally against the RGBM algorithm using their supercomputer. I believe Bruce Wienke said that they have also done actual dives with a dive computer with the RGBM with them for testing and verification.

Which RGBM algorithm did the Navy "validate"?

Looking at the Suunto website, it appears that Suunto computers use different algorithms, depending on which computer you're talking about:

Suunto Fused RGBM
Suunto RGBM

Which one of those did the Navy "validate"?

Also, are the algorithms you're using published for public review? How did the Navy get an implementation of your algorithm(s) to run on their supercomputer? Is the source code for that implementation available somewhere?

 

[JohnnyC]

Bruce Weinke SELLS his proprietary version of RGBM, that algorithm he personally developed. To say there's a conflict of interest in comparing something he developed and has a financial stake in is probably the most kind thing one could say about it.

"Validating" it against "Navy dives" sounds suspiciously similar to AG "validating" UTD's ratio deco by running tables against a variety of commonly used and well regarded algorithms and saying that it's proof that the other algorithms are broken because they don't match the table he made up.

Hell, RGBM bent Mark Ellyat like a pretzel on more than one occasion.

 

[drrich2]

But enough of algorithms for now in this thread. We can start a new separate discussion about algorithms if needed.

If the computer offers a choice of algorithms, or you can customize what it uses (e.g.: set your gradient factors), that may be so. If you're stuck with the algorithm it comes with, that's another story. Is the latter the case with the Core? If so, the desirability of the algorithm directly impacts the desirability of the computer.

There've been a number of threads on ScubaBoard where someone asks about which dive computer to get, somebody mentions Suunto, then this veer off into debating whether the alleged conservatism of Suunto's is troublesome or not.

I'm surprised Suunto hasn't gone dual algorithm just to shut people up!

Richard.

 

[JohnnyC]

I'm surprised Suunto hasn't gone dual algorithm just to shut people up!

Richard.

Probably because they paid a boat load of money to BW to use RGBM and at this point they're so entrenched that they'll keep it until the market dictates they change. Which probably won't happen because their cheap computers are generally well-regarded, and the people buying the Zoops and the Vypers are fine using them for recreational dives. If they lock it out, they just follow their DM's computer......

 

[scubadada]

...I'm not getting into the pro's and cons of algorithm, however I will say this (@scubadada ) I have carried out real world repetitive dives over multiple days with people using the Perdix (All on nitrox, generally to the 40m range) with the Eon set to -2 (most liberal) and Perdix set to it's most liberal in Rec mode, the Eon consistently has more NDL time...

Hi @Diving Dubai

Not sure why you picked me out this time. I have agreed with you previously, the Suunto fused RGBM algorithm set at -2 has almost exactly the same NDLs as DSAT on 1st dive, both more than Buhlmann ZH-L16C set at 45/95, particularly at depth. I have not had a chance to verify that the repetitive dives continue to be the same as DSAT, perhaps you have.

Good diving, Craig

 

[tbone1004]

Hi @Diving Dubai

Not sure why you picked me out this time. I have agreed with you previously, the Suunto fused RGBM algorithm set at -2 has almost exactly the same NDLs as DSAT on 1st dive, both more than Buhlmann ZH-L16C set at 45/95, particularly at depth. I have not had a chance to verify that the repetitive dives continue to be the same as DSAT, perhaps you have.

Good diving, Craig

of note, I believe that Neal Pollock is currently diving 50/70 and advocating that for recreational diving. He is not a technical diver

 

[scubadada]

The best suggestion yet was made by @tbone1004 Suunto could offer dual algorithm with whatever version of RGBM and Buhlmann ZH-L16C with GF. Divers would then have their choice. I would imagine this could give a great boost to Suunto products.

 

[Diving Dubai]

If the computer offers a choice of algorithms, or you can customize what it uses (e.g.: set your gradient factors), that may be so. If you're stuck with the algorithm it comes with, that's another story. Is the latter the case with the Core? If so, the desirability of the algorithm directly impacts the desirability of the computer.

There've been a number of threads on ScubaBoard where someone asks about which dive computer to get, somebody mentions Suunto, then this veer off into debating whether the alleged conservatism of Suunto's is troublesome or not.

I'm surprised Suunto hasn't gone dual algorithm just to shut people up!

Richard.

Why?

As tbone stated here: (my emphasis)

@Diving Dubai the RGBM algorithm works fine in the depths and times you're diving. It's when you get into trimix that it gets really wonky and far from anything recommended by current research. I'd have no problem diving it in nitrox/air depths, but would not consider it for trimix diving.

So for the vast say 90% of divers the RGBM algorithm is fine, and as I've mentioned above, the Eon set to it's most liberal, gives a greater NDL time than the perdix (set to it's most liberal in Rec mode) on repetitive dives. Its' fine down to the 50m (160') mark, which is beyond the capabilities of most divers. It doesn't give hugely different Deco times from my limited experience diving alongside others with OSTC running ZHL

Now obviously its a SB thing where people want teh longest possible NDL - fine, I'm deco trained and if my NDL goes past zero it's no biggy. I think the fused RGBM is good and has a nice spread of conservatism - from very aggressive to very conservative (over 5 steps) I can match it with most other computers or "detune it" to account for certain types of dive or if I'm not feeling 100%

Unfortunately there is always the regurgitated statement that all Suunto computers are bad, which is clearly untrue, For the general populous in the Rec world they are entirely acceptable, and as I can attest the algorithm is fine for the limits (depending on your agency) of Rec depths