Conservative Suunto

[diveaway]

Divers

I bought for my fiancee a Suunto Mosquito for her birthday and we put it to test last week on the caymans. I was using my good old Aladdin Air.
After two days of days and on the fifth dive the Suunto was showing 13 (!) minutes deco stop at 3 meters (sorry, we dive metric). The profiles of the dives were (32 meters - 30 minutes, 16 meters - 45 minutes, 5 meter - 30 minutes, day two: 30 meters - 30 minutes, 20 meters - 45 minutes).

Because we were diving in a group and my computer showed NO deco, we decided to return to the boat. Of course her computer was locked for the next two days.

Have you experienced similar effects with Suunto computers? What should we do, to get more closer results between our computers (Suunto and Aladdin)? I just think 13 minutes deco, when a second computer has NO deco at all ... there seems to be something wrong.

Ant help is appreciated!

Cheers

Ray

 

[O-ring]

You could get a Suunto or get her an Aladin? Only one solution and I am sure you will hear many more better ones, but that is the risk you run using different computers among buddy teams.

One computer is always going to read a little different, and for that reason, since I have a Vyper, we are getting my girlfriend a Suunto also...

--Eric

Another cheaper easier solution, although I have never tried it and am not sure it would work, would be to modify the conservatism settings (don't know about the Aladin, but the Suunto's have 'em) on one or both computers until you get similar results diving a test profile.

 

[Zept]

Check that her Mosquito is using its least conservative personal setting (P0, I think, but check your manual).

Did your girlfriend realise that her no-decompression time was running out? If so, why didn't you ascend?

Zept

 

[ymy]

I dive with the Mosquito also while most of my dive buddies dive with Alladins. Other than the optional safety stop of 3min at 15 feet I have never encountered any deco stops even on multi-day dives to 80 - 100+ ft on some dives. Two possibilities I can think of.

Zept's suggestion to check the altitude and personal settings is a very good idea. At P0/A0 it should be very close to the PADI tables.

The other possibility which I understand from reading the manual is the suunto RGBM model penalizes for fast ascents. It will flag for a "mandatory" safety stop (vs a deco stop) at 15ft. Violating this stop will not lock the computer ... but it will penalize you on subsequent dives by reducing the NDLs on subsequent dives. Check your dive profile to see if you had SLOW warnings in the dive profile. If you were doing a lot of "bounces" you may have been heavily penalized on later dives.

And finally, I don't think it would have gone to a 13 min deco stop immeadiately. You must have gone over its NDL for quite a while for it to go to 13min of deco.

 

[Rick Murchison]

Even at its least conservative settings, if you are accustomed to any of the Pelagics you'll find the SUUNTO to be infuriatingly conservative.
But...
If you're going to use a computer, use it.
Rick

 

[Manogr]

Wow...13 minutes dec stop on a Mosquito ???? serious...

SUUNTO are good computers and if they show a deco stop your girlfriend should follow it... It was a mistake following your computer since many factors are taken into consideration (fast ascents, previous dives etc)...

Even if you find now that the conservative profiles are used, since you did not know it then I believe that your fiance should stay and deco ! Otherwise why buy one ? Both of you can dive with your own!!


Manogr

 

[aquanut]

I would have to second what YMY says. Also, look at your profile. Two dives at 100' for 30min, a definate deco dive!
The suunto's are great computers, and they are not as conservative as people think. However, if you dive agressively,
(i.e. push the depth/time limits, too fast of an ascent rate) you will be heavily penalized. Consider this a good thing.

 

[ymy]

I recall reading somewhere that suuntos (and probably many other computers) are not designed to be used for deco diving. They can handle it ... but very heavily penalize anything past NDL limits.

As aquanut mentioned ... 100'/30min would have gone past NDL even on a first dive. Even Alladins would have gone to deco. I assume that the actual time at 100' was not 30min but it was some sort of multilevel.

Most likely it was fast ascents. Suunto's don't like ascents faster than 30'/min. During my initial dives, my mosquito kept asking me to slow down. I must say it has made me a better diver.

Another thing is that the mosquito has a diver's alert symbol during SI if it is penalizing you for fast ascents etc.

 

[O-ring]

I would agree with ymy...the only people I know using Suuntos for deco (vypers) are using them in gauge mode only (depth, time, temp, etc.)...

 

[john_a]

Suuntos do tend to be somewhat more conservative than most computers and do penalize the diver more for aggressive behavior - particularly for ascents in excess of 30 ft/min. That said, however, they are not that different than other computers.

In a direct comparison, a friend of mine took 3 computers on a series of dives of ND and deco dives - a Vyper, a Cochran Genesis, and a Uwatec Aladdin (I was with him and compared the results with my own Oceanic Data Plus). At no time during the 7 dives we did over 3 days, did any of the computers disagree on NDL by more than 2 minutes. At depths below about 70', they were all within 1 minute of each other. When deco obligations were incurred, ceiling depths were consistent and Total Ascent Times agreed within 2 minutes.

What I suspect happened here (original post) is that the diver in question ignored one or more mandatory ceilings on the Suunto either as a result of exceeding NDL or, more likely, failing to complete a mandatory safety stop (due to MD>100ft or AscRt >33ft/min).

This of course begs the question of why this was not noticed until the end of the dive? Moreover, why was the advice of the computer ignored? <soapbox> COMPUTERS ARE NOT MAGIC TALISMANS - SIMPLY HAVING ONE DOES NOT CONFER DCS RESISTANCE UPON YOU - LEARN HOW TO USE THE BLOODY THING, LEARN WHAT IT IS TELLING YOU, LEARN WHY IT IS TELLING YOU WHAT IT IS TELLING YOU, AND LEARN WHAT CAN CAUSE A VIOLATION </soapbox>

dsao