Which decompression algo does GUE use?

[rongoodman]

Interesting. Suunto sure has no problem referring to it as RGBM in their manuals. It sounds reasonable to me that modeling bubbles would take more "computational horsepower" than the way I understand Haldanean models work.

Actually, I've never seen them refer to it as anything but "Suunto RGBM".

 

[nadwidny]

Actually, I've never seen them refer to it as anything but "Suunto RGBM".

It should be "Suunto Keep You in The Water Forever".

Had one, hated it. The profiles were so long it was almost funny.Luckily the battery was easy enough to pop in and out to reset it.

 

[boulderjohn]

Actually, I've never seen them refer to it as anything but "Suunto RGBM".

Correct. I think that is the way they differentiate it from pure RGBM--but they definitely have Weinke's approval for it.

 

[rjack321]

Correct. I think that is the way they differentiate it from pure RGBM--but they definitely have Weinke's approval for it.

Pay money, use name...

Suunto's version is not really suitable for deco diving honestly. Certainly not if you dive with anyone else since you'll be in the water 2x longer

 

[boulderjohn]

It should be "Suunto Keep You in The Water Forever".

Had one, hated it. The profiles were so long it was almost funny.Luckily the battery was easy enough to pop in and out to reset it.

Pay money, use name...

Suunto's version is not really suitable for deco diving honestly. Certainly not if you dive with anyone else since you'll be in the water 2x longer

I wonder if Suunto has two versions--the one they put on their recreational computers or the one the use on their decompression computer, the HelO2. I noticed that the wording of descriptions varied ever so slightly when I looked at them. I don't have either with me so I can't quote, but IIRC, the recreational computers referred to the "Suunto RGBM" algorithm, and the HelO2 specifically referenced Weinke in naming it.

I had two experiences on successive days with the HelO2, soon after it was brought out. My buddy and I were doing a wreck at about 200 feet using V-Planner as our guide. My buddy said he had just gotten the new HelO2 at a keyman price and wanted to see what it would do. He said he had tried to set the parameters as close as possible to V-Planner. Well, as we ascended and the HelO2 started to vary, he decided he did not want to violate the HelO2, and we ended up following it instead of the V-Planner schedule. There were about 6 people doing the dive in addition to us, and we all had just about the same bottom time. Everyone else got out of the water long, long before us--at least 20 minutes. When we finally emerged from our long underwater stay, everyone else was frankly pissed off at us.

The next day we did a deeper dive--about 260 feet. My buddy brought the HelO2 again, but he said we would stick to the V-Planner schedule no matter what. We did--followed it perfectly. During our 30 foot stop, the HelO2 was so mad at us that it went into error mode.

For those who don't know, the V-Planner schedule will keep you in the water longer than some other algorithms, so it is by no means a fast algorithm.

 

[Diver0001]

I've been diving regularly with someone who uses a Helo 2 and it seems to dictate an ascent in the off-gassing zone of about 1 metre per minute.

Moreover, there doesn't seem to be any setting with this computer for ascents faster than about 1m/min. It just errors out. It's as though the ceiling that it calculates is whatever depth you're at right now. It's a poor implementation at best and possibly a software error at worst.

If you just accept the fact that it ascends at 1m/min then you can follow it and make a clean deco but you won't start dropping deco minutes until you're at 6 metres, which leads not only to longer ascents but considerably longer run times than vplanner or even other Suunto computers, depending on the dive. Personally I don't like what it does because it is counter intuitive and the slow ascent speed doesn't correspond to anything about deco theory that you think you know.

In my mind, either Suunto knows something about deco theory that theoreticians aren't telling us, or there's something wrong with the Helo-2.

R..

 

[rjack321]

For those who don't know, the V-Planner schedule will keep you in the water longer than some other algorithms, so it is by no means a fast algorithm.

At zero conservatism it seems pretty fast to me. I have not done a side by side with GF 100/100 but its in that ballpark. I use conservatism level 4, the "default" starting setting which roughly corresponds to GF 30/85 is level 2.

 

[LiteHedded]

As the exposures get longer VPm becomes absurdly faster

 

[rongoodman]

the HelO2 was so mad at us that it went into error mode.

What does it mean for it to go into error mode--does it actually lock you out and quit functioning? If so, that's just crazy.

 

[Diver0001]

What does it mean for it to go into error mode--does it actually lock you out and quit functioning? If so, that's just crazy.

All Suunto computers go into error mode (stop calculating stops) when you go above the ceiling for more than 3 minutes. IIRC it will continue to display depth and time but that's it.

The Helo-2, from what I've seen (which means doing a dozen or so deco dives using air/nitrox with someone who uses it) doesn't seem to make a distinction between an optional stop (a calculated deep stop below the ceiling) and a mandatory stop (at the ceiling). What it seems to do is equate the stop depth of a deep stop to the ceiling. If you ignore a deep stop and ascend above that, you have a very limited bandwidth of flexibility and it seems overly prone to error-out. I assume this is happening because it's using RGBM which doesn't calculate a ceiling in the same way as a Buhlmann algorithm does.

What this means in a practical sense is that it does not seem to tolerate an ascent faster than about 1m/min as you get shallower (say under 21 metres). If you were to travel from 21m to your ceiling at 3m/min like a Buhlmann algorithm would allow, it would lock out before you reached the ceiling. If I'm not mistaken it the conservatism can be adjusted to some extent (3 levels) but we haven't gotten around to playing with that yet. I don't know if he has his set to it's most aggressive setting or not, but I think it might be, since that's normal the default for a Suunto computer.

Anyway, tldr; it's a nag and a moody one too.

R..