Can Suuntos be adjusted to not be as conservative?

[victorzamora]

Good description, though I think "randomly" and "arbitrarily" are incorrect. It's an algorithm--it inherently works the same way every time. Nothing random or arbitrary. Unpredictable to all who are not Suunto engineers, yes. I think "opaque" is a good word for Suunto RGBM, as opposed to open or published models like Buhlmann ZH-L16.

Well, the computer isn't being arbitrary but the algorithm seems to be. There's no evidence that reverse profiles are bad. There's no evidence that sawtooth profiles are bad. Bubble models and Tissue Loading models both seem to agree. Suunto has arbitrarily decided to punish for those kinds of things despite lacking scientific basis. RGBM is an algorithm, and Suunto RGBM is an algorithm. But RGBM and Buhlmann are both based off of mathematical models of physiological phenomena. Suunto "arbitrarily and randomly" added factors on top of that.

They're certainly opaque, and very much impossible to predict, but I do think that "random and arbitrary" are accurate statements. Pure Haldanean or RGBM bubble models don't produce the sawtooth, short SIT, or reverse-profile penalties that the Suunto, Cressi, and Mares "flavors" seem to produce (with Suunto being the worst).

 

[divad]

Don't do sawtooth profiles, reverse profiles, short SITs, etc.

If you're able to, this is probably a better idea than ****ing with your PO2.

 

[Hatul]

The Suunto is punitive if your surface interval is < 1 hr and your setting will have no effect on this. The algorithm is not uniformly conservative. For example on a single dive I found my Vyper more liberal than my Galileo, so your tweak may make the computer overly liberal in certain situations and put you at risk.

 

[victorzamora]

If you're able to, this is probably a better idea than ****ing with your PO2.

Oh, I think it's an awful idea to screw with your FO2s except for ADDING conservatism (diving nitrox as air, or 32% as 28%). I don't even like THAT as an idea, though, as I'd rather simply implement conservatism as I see fit. That way I don't lock out my computer if I decide to stay longer (whale shark swims by, for example).

To me, the best way to reduce the Suunto-awfulness is to buy a non-Suunto product.

 

[DavidFL]

My Suunto Cobra2 has an "attenuated RGBM mode.....the settings/options are "full RGBM effects (100%)" and "attenuated RGBM (50%). As far as I can tell, my older Suunto Gekko doesn't have that option. I don't personally use the "attenuated RGBM" mode, but if I understand the manual correctly it is less conservative than the "full RGBM" mode.

 

[RJP]

So I've heard a lot of people complain about the Suunto computers on here because they're so conservative compared to other brands. Can't this be adjusted by just switching your pO2?

I hear this refrain frequently, so it must be true somewhere. However, in nearly 1,000 dives with a Suunto Vytec DS I've never encountered it. My usually buddy - with whom I've probably done in the neighborhood of 250-300 dives - dives an Oceanic and I've never had a situation where my Suunto has limited our bottom time.

Back in December we did a dive on the Windjammer in Bonaire. My max depth was 204ft, his was 199ft. Planned run-time was 87min. At our last stop my Suunto Vytec had me doing one more minute to clear than his Oceanic gave him.

As mentioned above, it will ding you for things like a short SIT, sawtooth/reverse profiles, and bouncing. On those occasions it will sometimes give me a 4min stop instead of 3min.

If someone wants to call that "more conservative" I guess they might be technically correct.

 

[KenGordon]

Today I did a 46m dive with run time of 80 minutes including 3 minutes of safety stop once the computer was clear.

If I give multideco the dive to plan for 30/70GF (the out of th box default for a Petrel) I get a run time of 77 minutes. 45/70 gives 76 minutes and 45/85 69 minutes. Guess which brand of computer I was using.

Which setting would you choose? Now those are profiles developed and (at least the software) tested by people to a commercial level of quality. So maybe they are all good.

By fudging the O2 fraction on a computer you are into uncharted and not formally (or at all?) tested territory.

Even simple dissolved gas models are non linear. Small changes in one parameter can cause significant, non obvious and unexpected changes in results. Unless you are very good an mental arithmetic while under the influence of narcotics then you will not be check the computer's working very well.

How will you decide how much to fudge your deco?

Here is a radical proposal. If you think the NDL difference between 32% and air would make all the difference to your enjoyment, then dive 32%.

 

[victorzamora]

Today I did a 46m dive with run time of 80 minutes including 3 minutes of safety stop once the computer was clear.

If I give multideco the dive to plan for 30/70GF (the out of th box default for a Petrel) I get a run time of 77 minutes. 45/70 gives 76 minutes and 45/85 69 minutes. Guess which brand of computer I was using.

Which setting would you choose? Now those are profiles developed and (at least the software) tested by people to a commercial level of quality. So maybe they are all good.

By fudging the O2 fraction on a computer you are into uncharted and not formally (or at all?) tested territory.

Even simple dissolved gas models are non linear. Small changes in one parameter can cause significant, non obvious and unexpected changes in results. Unless you are very good an mental arithmetic while under the influence of narcotics then you will not be check the computer's working very well.

How will you decide how much to fudge your deco?

Here is a radical proposal. If you think the NDL difference between 32% and air would make all the difference to your enjoyment, then dive 32%.

Yeah, so, again, Suuntos suck on subsequent dives. They suck for adding fudge factors arbitrarily. They suck for not being predictable. I'm not saying one mostly-square dive is bad on a Suunto. I'm not saying they're dangerous. I'm saying the algorithm sucks, and it being so opaque and arbitrary makes it suck even harder. I even said above:

On a single dive of square profile they're really not conservative. However, they start adding really unpredictable fudge factors arbitrarily.

 

[Lorenzoid]

I wonder what the Finnish word for "fudge factor" is? I can just hear those Suunto engineers (in Finnish) discussing adding fudge factors. From what I've read (on SB, so take it for what it's worth), the Wienke RGBM part sits on top of a basically Haldanean model. But "fudge factors"? You really don't give Suunto's engineering team any credit whatsoever, do you.

 

[DenbyS]

I dive with a Zoop. I noticed I had less bottom time than my buddies who I think all have Uwatec computers. I found a simulator for the Zoop as an add-in to a dive planner for the iPad. It helped me understand what to expect if I blew past my ndl and started to accrue ascent time. I learned how to plan for that extra time, found it accurately predicted how that ascent time would suddenly disappear if I ascended to about 30', and how many minutes beyond ndl really turned into an extended "deco" time.