Suunto Computers - Final Conclusion.

[scrane]

I would have thought that admitting to ignoring your Zoop once you've bent it is proof enough of the failure of that paradigm.

Hopefully you have rectified that situation.

It's been relegated to the closet for 23 months now. I really shouldn't bad mouth it until I sell it.

 

[doctormike]

Actually, getting penalized by a piece of equipment that I paid for would get my goat in any situation. A dive computer should calculate the nitrogen loading and recommend actions based on that. Added penalties beyond what the math in an algorithm works out are a waste of time, and insulting.

Is your opinion that since you paid for the dive computer, it should just "let" you do whatever profile you like?

I don't dive a Suunto myself, but you really should rethink your understanding of what a dive computer does. It minimizes decompression stress. An algorithm isn't some eternal rule handed down from God, but a mathematical guess of how to minimize decompression stress. The engineers at Suunto have decided (with good supporting evidence) that there are aspects of a dive profile which may increase decompression stress even if they aren't part of the standard algorithm inputs (time, depth and mix).

For example, a sawtooth profile can do that, even if you stay within the overall NDLs (guess how I figured that out). So would you object to and be insulted by a dive computer that "penalizes" you for such a profile by giving you a shorter NDL?

Hey, maybe you think the the Suunto engineers are wrong, and you disagree with them. Fair enough, even though the software is proprietary and you don't know exactly what it is doing. They are selling a product, and that product is a mathematical model that minimizes decompression stress. It's fine not to buy the product, but I don't think that you should object to the very idea that they are selling the product.

 

[kelemvor]

Is your opinion that since you paid for the dive computer, it should just "let" you do whatever profile you like?

I don't dive a Suunto myself, but you really should rethink your understanding of what a dive computer does. It minimizes decompression stress. An algorithm isn't some eternal rule handed down from God, but a mathematical guess of how to minimize decompression stress. The engineers at Suunto have decided (with good supporting evidence) that there are aspects of a dive profile which may increase decompression stress even if they aren't part of the standard algorithm inputs (time, depth and mix).

For example, a sawtooth profile can do that, even if you stay within the overall NDLs (guess how I figured that out). So would you object to and be insulted by a dive computer that "penalizes" you for such a profile by giving you a shorter NDL?

Hey, maybe you think the the Suunto engineers are wrong, and you disagree with them. Fair enough, even though the software is proprietary and you don't know exactly what it is doing. They are selling a product, and that product is a mathematical model that minimizes decompression stress. It's fine not to buy the product, but I don't think that you should object to the very idea that they are selling the product.

I think what I'm saying is that I want the dive computer to accurately calculate my decompression. I don't want it to add extra time to a surface interval or stop arbitrarily. If I'm down long enough to warrant the stop time then fine. If my nitrogen load is high enough that I must take an hour surface interval to do the next dive I'm planning that is also fine. I don't want the computer to try and control my dive, I want it to calculate and inform based on the dive that I did. I'll decide what to do with the results. If I happen to decide to get into mandatory deco stop level of loading, then I don't want the thing to punish me with a day off. I want it to calculate my stop time, and offgas time so that I can do my next dive whenever it's really feasible to do the next dive.

With a non-suunto computer on the vacation dives I've experienced where I'm doing 3-5 dives a day, it's all worked out just fine. No mandatory deco, etc. Like I said before though - my buddies carrying suunto's weren't so "lucky" (not sure that's the right word, but hopefully gets the idea across). I'm pretty sure their profiles weren't significantly deeper than mine because I didn't see a shovel on a single one of them.

Like I said, if you are aware of what a suunto does and consider that desirable then far be it for me to dissuade someone from buying one. The problem is that most people find out about this stuff after they've already got the computer wet and can't return it (unless they got it online). I'm just trying to disseminate the information about this behavior and what it might mean to a regular diver on a common dive trip to places like Cozumel or Roatan.

When I went shopping for my first dive computer I went specifically to buy a suunto. Luckily for me, the shop also sold another model which I ultimately selected because I liked the screen better. At that time I had no idea dive computers didn't all use the same standard algorithms so it really was luck.

 

[doctormike]

I think what I'm saying is that I want the dive computer to accurately calculate my decompression. I don't want it to add extra time to a surface interval or stop arbitrarily. If I'm down long enough to warrant the stop time then fine. If my nitrogen load is high enough that I must take an hour surface interval to do the next dive I'm planning that is also fine. I don't want the computer to try and control my dive, I want it to calculate and inform based on the dive that I did.

Right, but that's the whole point. A computer that decreases your NDL because you did a short SI or a sawtooth profile, IS accurately calculating your decompression. And another computer that does NOT do those things, is ALSO accurately calculating your decompression.

I know that seems strange, but it's true! There is no "accurate" ascent profile that you can calculate which will 100% keep you safe if you follow it, and 100% get you bent if you don't. It's a bright line through a grey area. The way you are thinking about it does not reflect the reality of decompression science.

The computer isn't penalizing you arbitrarily, it's trying to keep you safe. Suunto or Shearwater, they all do the same thing.

If you don't want a computer to control your dive, why would you use one? That's what it does.

 

[Fires]

Right, but that's the whole point. A computer that decreases your NDL because you did a short SI or a sawtooth profile, IS accurately calculating your decompression. And another computer that does NOT do those things, is ALSO accurately calculating your decompression.

I know that seems strange, but it's true! There is no "accurate" ascent profile that you can calculate which will 100% keep you safe if you follow it, and 100% get you bent if you don't. It's a bright line through a grey area. The way you are thinking about it does not reflect the reality of decompression science.

The computer isn't penalizing you arbitrarily, it's trying to keep you safe. Suunto or Shearwater, they all do the same thing.

If you don't want a computer to control your dive, why would you use one? That's what it does.

Couldn't agree more. Also read your article, and found it very interesting! We often when teaching always have concerns about performing multiple CESA's and thus end up doing them as the first dive of the day (Dive 3, day 2) in order to have the least amount of N in our system already.

So in actual fact, although people might hate what Suunto is penalising them for, they seem to be on the right track, especially if you consider your situation.

But I think most important is what you said here now. Which is that at the end of the day no computer or algorithm knows 100% what your body is doing. I feel like there is a lot of hate towards Suunto for "arbitrary" (I say that lightly) reasons, like it limits my dive. When other algorithms are not the end all and be all 100% perfect and safe tables. If that were the case, there would only be the "leading"/correct algorithm, and the rest no one would trust anymore and thus not use.

I have always been happy diving a Suunto as it is seen as more conservative. Yes you can change to 50% on the RGBM, but I really wouldn't recommend that unless you know what you are doing. I am now planning to get into tec, so maybe my opinion will change, but I don't think so, as I will always rather stay on the conservative side. There is always another day and another dive that I would rather come back for compared to pushing the limits.

Until we have integrated (blood stream or something) computers, we will never know 100%

 

[doctormike]

Until we have integrated (blood stream or something) computers, we will never know 100%

Hah! And even then we won't know...

One of the most important concepts in medicine is "there is a bell curve for everything". Two people are exposed to the exact same virus or toxin, one gets sick and one doesn't. Why? Because there is a bell curve for everything.

 

[Fires]

Hah! And even then we won't know...

One of the most important concepts in medicine is "there is a bell curve for everything". Two people are exposed to the exact same virus or toxin, one gets sick and one doesn't. Why? Because there is a bell curve for everything.

And here I was thinking I was paying my doc to treat me, meanwhile he is gambling with bells or something....real nice

 

[Magnus Lundstedt]

If it did just that, there would be no such thing as a penalty. I believe it adds an additional penalty on top of the calculated values. Of course that part is complete conjecture based on the manual, user reports, etc. Nobody really knows for sure because nobody knows how suunto's algorithm works unless they work for Suunto. The manuals do mention penalties, so I know it's not a crazy theory some divers came up with.

No, it does just that.

Then it is difference between different Suunto, the entry level Zoop, at least the old model, did penalize you a lot more for repetitive diving than the other models, and the DX and Eon (steel/core) use another algorithm (fused RGBM vs SRGBM, SRGBM is actualy not a RGBM algorithm....) than the others.

It is not reasonable to say that "Suntoo" do this and that, if you not specify what model you talk about.

I see the problem more bee that they run a "closed box algorithm" where you don't rely know how it works, but in my experience (cobra) and friends experience (D9, DX, D4i, vyper) they work, a couple of them do 3-6 dives a day for 6-7 days a week.

 

[GreggS]

I have always been happy diving a Suunto as it is seen as more conservative. Yes you can change to 50% on the RGBM, but I really wouldn't recommend that unless you know what you are doing.

I don't know which computer you are using, but the only one I've seen where the user can reduce the RGBM by 50% is the Vyper Air. I had one for a year before it went all wonky on me and had to be replaced under warranty with a Vyper Novo, which does not have this option. I've also had a Gekko, my wife has a Zoop, and I have a console mounted Vyper (non AI) as a back-up, none of which have this option. Other than that, I don't know if any other models have had this feature or not. Just wanted to clarify that not ALL Suunto computers can reduce the RGBM.

 

[Magnus Lundstedt]

I think what I'm saying is that I want the dive computer to accurately calculate my decompression. I don't want it to add extra time to a surface interval or stop arbitrarily. If I'm down long enough to warrant the stop time then fine. If my nitrogen load is high enough that I must take an hour surface interval to do the next dive I'm planning that is also fine. I don't want the computer to try and control my dive, I want it to calculate and inform based on the dive that I did. I'll decide what to do with the results. If I happen to decide to get into mandatory deco stop level of loading, then I don't want the thing to punish me with a day off. I want it to calculate my stop time, and offgas time so that I can do my next dive whenever it's really feasible to do the next dive.

My Suunto (Cobra) do exactly what you say you want it to doo, it do never add extra surface time, it calculate and inform me based on my resent diving, it do not punish me with a day of if i go into deco, it calculates my stop time and offgas time so I can do the next dive just when I want to. But if I decide to not do the deco my DC have calculated that i need, then it will try to lock me out for 24 hours. (it will try, but its easy to get in, but do this on your own risk becouse it "forgets" your nitrogen load.)