Suunto: how conservative is the algorithm?

[sasscuba]

Course it is! 130' is regarded as the limit for recreational diving.

I find that Suuntos tend to get more restrictive on the third long dive of a day, and then on subsequent days. Prior to that point I don't see much difference. I wear a Stinger all the time, and have also recently been using a Vyper. I noticed the same with both of them, compared with the DiveRite Nitek+ that I also always wear.

That said, I like the quality feel of all Suuntos that I've used, and I'll continue to use them. What I don't like is the abysmal battery consumption of the Stinger, and the fact that Suunto won't sell me the tool to open it, so I have to send it to them in the USA just less than annually.

I also have the Stinger but change my own battery. Between my father and I, he made a tool out of steel that easily opens the stinger and it takes less than 5 minutes to change the battery. Granted you cannot pressure test it in a tank but we have been changing the batteries for awhile now with no leaks. It is very easy to do and cost less than $5 for the o-ring and the battery. Here is a pic of the tools. You have to make the tool make contact with the square indents and not the round ones to open. Scott.

 

[Diver Dennis]

I've never had a Suunto shorten any of my recreational type dives but I do notice my deco times are longer. Still, I'll keep them.

Very cool tools Scott.

 

[peterbj7]

Yes Scott, very cool. Fancy making me one?

I'm sure the batteries are standard (I've never seen one!) but how do you get the O-ring? Is it a standard size or do you have some pull with Suunto?

Do you know whether Suunto also change the push-button seals when they change the battery? Do you have any idea how often they should be changed, and how to get hold of them?

 

[Charlie99]

I've never had a Suunto shorten any of my recreational type dives but I do notice my deco times are longer.

That's what I've noticed during a trip where my buddy had a Suunto and I was using an Oceanic. He would routinely go into decompression, while my Oceanic computer would show loading well up into the yellow caution zone, but with some NDL time remaining.

I would do my ascents and stops in my normal fashion and around the time that my computer got back into the green zone, his computer would clear the decompression obligation.

As Diver Dennis says, the conservative computer didn't reduce my buddy's bottom times, it just extended his decompression times. We dove so that we had both the air and time needed to do the desired decompression.

It worked out well, because I treat the yellow zone on my Oceanic compute as "psuedo-mandatory decompression" and most of time will do the stops and hang times needed get it back to green (or nearly so).

 

[4sak3n]

I have noticed (as Azza pointed out) that my Vytec gets very strict about fast ascent warnings.

I once had it extend my safety stop to 5mins and make it mandatory simply because I exceeded 10 m/min ascent rate. Yes, I am sure that that is the reason why it rapped me over the knuckles because otherwise the rest of my dive (profile, bottom time etc) was perfect.

A leather-clad computer with an ascent fetish, who would have thought it?

 

[sclakediver]

OK mason, I finally had the opportunity to look at my profiles.

We made three dives last Fri, threw in a reverse profile and then a shallow dive for the third dive. Dive one, 100' 43 min total dive time, the Suunto gave me two minutes more bottom time than the Uwatec at depth. Dive two, 120' 31 min total dive time, the Suunto and the Uwatec gave me the same amount of NDT. Dive three 45', 38 min total dive time, the Suunto had a much shorter NDT than the Uwatec. It must be the depth, not sure. The Suunto was about 25 minutes shorter then the Uwatec. Not that it mattered at this depth. I certainly didn't have enough air left after the first two dives to spend another hour and a half in the water.

Sat saw another reverse profile. Dive one, 38' 39 min total dive time. Again the Suunto was about 25 minutes shorter than the Uwatec. Dive two, 111' 40 min total dive time. The Suunto was two minutes shorter than the Uwatec on this dive.

I have never put the Suunto into deco, so I can't comment on deco obligations being too conservative. I like the Gekko and am thinking about trading it in for a Vyper or Cobra. I like PC interface capabilities and the option to change to gauge mode.

Conclusion. There's not a significant difference. I would suggest buying a computer with a user replaceable battery.

 

[viceroy]

I am sure it will make that diver mad to cut his dive short because of me. Any help on this topic would be appreciated.

As stated before, I'd also stay very far away from any diver who got mad because you cut the dive short.

When I started taking my diving further than OW, I was lucky enough to have a very good instructor who made it very clear that any diver can call any dive for any reason...no questions asked.

My fiancee has just qualified and I've told her the exact same thing...If she wants to abort any dive at any time, then thats what we do.

Up until tonight only I have been diving on computer. She's been diving tables which naturally meant that she had a much more limited dive time than mine (and I use a Stinger ) and when her dive time was up we'd ascend.

Tonight she picks up her Nemo Sport which luckily means she can stay down longer, but regardless...whoever's computer has the shortest NDL is the one we both will use as a guide about when to surface.

 

[S&V]

My wife and I both use Suunto computers, Gekko for me, and Cobra2 for her. I have been looking for additional documentation on the RGBM algorithm for the same reasons as the OP and responders, and found a free Suunto pamphlet at our LDS last weekend.
It is not technical documentation, but it does give a considerably expanded discussion of the design goals/trade-offs Suunto uses in RGBM. I think it helps answer most of our basic questions.
I assumed Suunto had this pamphlet in some form at their website as well, and indeed they do, it is in .pdf format, here is the link:
http://www.suunto.com/media/suunto/NewWorlds/Diving/pdf/UserTips/Suunto_RGBM_304b5.pdf

 

[mason417]

As stated before, I'd also stay very far away from any diver who got mad because you cut the dive short.

When I started taking my diving further than OW, I was lucky enough to have a very good instructor who made it very clear that any diver can call any dive for any reason...no questions asked.

My fiancee has just qualified and I've told her the exact same thing...If she wants to abort any dive at any time, then thats what we do.

Up until tonight only I have been diving on computer. She's been diving tables which naturally meant that she had a much more limited dive time than mine (and I use a Stinger ) and when her dive time was up we'd ascend.

Tonight she picks up her Nemo Sport which luckily means she can stay down longer, but regardless...whoever's computer has the shortest NDL is the one we both will use as a guide about when to surface.

I will be diving with my wife when she gets certified soon. I have had some back luck with diving buddies, they seem to not care about being a better diver. Oh well, my wife will be my best buddy!

 

[Jrock1062]

OK mason, I finally had the opportunity to look at my profiles.

We made three dives last Fri, threw in a reverse profile and then a shallow dive for the third dive. Dive one, 100' 43 min total dive time, the Suunto gave me two minutes more bottom time than the Uwatec at depth. Dive two, 120' 31 min total dive time, the Suunto and the Uwatec gave me the same amount of NDT. Dive three 45', 38 min total dive time, the Suunto had a much shorter NDT than the Uwatec. It must be the depth, not sure. The Suunto was about 25 minutes shorter then the Uwatec. Not that it mattered at this depth. I certainly didn't have enough air left after the first two dives to spend another hour and a half in the water.

Sat saw another reverse profile. Dive one, 38' 39 min total dive time. Again the Suunto was about 25 minutes shorter than the Uwatec. Dive two, 111' 40 min total dive time. The Suunto was two minutes shorter than the Uwatec on this dive.

I have never put the Suunto into deco, so I can't comment on deco obligations being too conservative. I like the Gekko and am thinking about trading it in for a Vyper or Cobra. I like PC interface capabilities and the option to change to gauge mode.

Conclusion. There's not a significant difference. I would suggest buying a computer with a user replaceable battery.

I have a question for you is your RGBM set at 100% or at 50 % I have mine set at 50 and find it no more conservative than other computers