suunto algorithm question

[HeatCker]

just wondering ...
i dive with a suunto computer
the computers conservative settings are set to "0", partial pressure set to 1.6 for nitrox
when doing repetitive and multi day diving it has become obvious that the rgbm algorithm is very conservative
suuntos are known to be very conservative, this applies whether diving on air or nitrox
many times on trips to Coz my computer forces me to ascend much sooner then others
sooner than other divers that are diving same profiles and number of dives, ie my dive buddy
sooner than DM's that are doing 4 dives a day compared to my two dives a day, we're both on nitrox
since a dive computer is basically a timer with alarms ...
and since other computers/algorithms (oceanic, scubapro) allow more bottom time...
i'm wondering if setting my suunto comp to a higher percentage would be a poor idea
as an example, diving with 32%, set the comp to something like 35% "to be more in line with other algorithms"
as an example, diving with 21%, set the comp to something like 25% "to be more in line with other algorithms"
i usually stay fairly shallow so in all cases MOD would not be a concern
has anybody done this or have thoughts on this, positive or negative
thanks

 

[tbone1004]

only solution there mate is to get a computer with a better algorithm.... Hate to say it, but since no one actually knows what the Suunto's penalize divers for in the water and outside of Suunto's software you can't actually predict what it is going to do, it's just not worth it. Sell this one, support local business and buy a Shearwater. You will have infinitely more control over what the computer is doing, and it won't lock you out ever.

 

[HeatCker]

tbone .. thanks for the feedback
lets go back to my original statement "a dive computer is basically a timer with alarms"
i would say all of my diving is conservative, recreational diving, ie above 100', mostly above 80'
if many other computers allow divers to dive longer bottom times with no ill effects...
then that is what i am trying to achieve with the % adjustment idea i have suggested
in essence making the suunto computer more in line with other computers bottom times
its all about getting "comparable bottom times", ie, if they can dive it then so should i be able to
keep in mind that i wouldn't just arbitrarily set the computer to 40% and hope for the best
i suppose the best way to answer my own question is to dive with two computers and watch the NDL
bottom line is i'm just trying to make the suunto a little less conservative, to add another adjustment setting so to speak
simliar to using 1.6 pp or 50% rgbm

 

[Scubanoobi]

There was a similar thread about a year ago, the general consensus was that it's a bad idea.

I had a Suunto and now own a petrel BTW.

Fast ascents, short SI's and skipping safety stops are the big factors with Suunto RGBM. RGBM 50 only makes a difference on dive #2, dive 3 or higher there is no difference (I did a lot of testing).

 

[Asteve]

I had the same problem with the Cressi Leonardo, I was using it at Coz also. I was diving air. One of the DM said he had had the same computer and need to set it on a nitrox %. to get longer dives, did not tell what setting he set it for.
Since I have been home have done a little reading and need to a lot more. I have compare the pre-dive computer mode against the US dive table (air) and it looks like 25% nitrox is still a little conservative against the chart.
I have to agree with tbone 1004 about what the computer in all situation and multiply dive will do at different settings.

[FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]I suppose the best way to answer this question is to dive with two computers and watch the NDL. Seem like a lot of work to save a few bucks and you still will not know what you have.[/FONT]

[FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]I hope this thread get a lot of reply's. [/FONT]

 

[tbone1004]

and what I am trying to say is that is unsafe because you don't actually know the algorithms that are being run. You have three options.

1. sell it and get a computer that you can trust and aren't pissed off at. Are you really going to go through all of the different nitrox mixes and go in and chart the NDL differences for each mix at each depth profile? That is what it would take to make an intelligent guess at how many points to change it. Accept that Suunto is not a good dive computer if you are making lots of repetitive dives, and either deal with it, or get rid of it. Hollis DG03 are $250 new, Dive Rite Nitek Duo is about $150 on ebay, Shearwater Petrel is the baddest of the bada$$ and is about $700.

2. Keep the computer and use it in gauge mode and dive tables. They are a lot more than a timer with alarms, they are continuously tracking your depth and plotting it against theorized tissue loading of any number of compartments to try to best mimic the inert gas loading in your tissues. Better computers have more compartments for better accuracy, but they are far more than timers. Or put it in gauge mode, approximate with tables and dive based off of your buddies NDL's, again not smart, but surely smarter than adjusting your nitrox mixes to trick your computer.

3. Keep it, and get over it.

Not trying to be an a$$ but even though you are doing recreational dives you should never tell your computer you are diving a richer mix than you are to boost your NDL's. It's a recipe for getting bent.

 

[scubadada]

I would not try to fake out your dive computer to make it more liberal. You can always make a liberal computer more conservative, but nothing kosher you can do with a conservative computer to make it more liberal.

 

[HeatCker]

thanks for the feedback guys .. appreciate your input

 

[Dirty-Dog]

I had the same issue with a Suunto - it had me in deco while the Aeris I was using for a backup showed plenty of NDL.
There are two possible solutions.
1 - Sell the Suunto and buy a different computer.
2 - Put the Suunto in gauge mode and plan your dive the old fashioned way.

 

[KeithG]

There was a similar thread about a year ago, the general consensus was that it's a bad idea.

I had a Suunto and now own a petrel BTW.

Fast ascents, short SI's and skipping safety stops are the big factors with Suunto RGBM. RGBM 50 only makes a difference on dive #2, dive 3 or higher there is no difference (I did a lot of testing).

i believe the general consesus is that the suunto algorithm gives normal NDLs UNLESS you violate one of their special safety guidelines. if you violate, then it punishes you on subsequent dives with reduced NDLs. no violations, then you get NDL very similar to "normal" computers. the amount of punishment appears to be a secret.

this theory is all conjecture based upon reported behaviour.

i was an a liveaboard where the DM sent a diver back into the water because the diver rushed up the dive ladder and got a fast ascent alarm. the DM was worried the computer would lock out (based on prior lock out experiences).

i have also heard that 59 minute surface interval will also result in significantly reduced NDLs while 60 minutes allows the computer to provide normal NDLs.

so i think there are many people for which suuntos work just fine since they do not incur violations and hence no need for punishment. i have seen them used for 5 dives a day on liveaboards with no issues.

if you do a search and a bunch of reading you may be able to get additional information about suunto behaviour.maybe you are being punished?