Suunto query

[Smudger]

Hi

Until recently I was diving with my 8 year old Suunto Vyper and my wife on her Gekko.
When she had the Gekko our NDL was broadly the same. She is now using her new D4i and it seems to be giving her between 10 and 15 minutes more bottom time. Not sure why. They are both Suunto, It's the same RGBM model (I think), both computers set to 100% RGBM and personal settings both at P0 (least conservative). We are diving in the Philippines at the moment and our profiles are very similar but of course she is in a strop because I'm cutting her bottom time down.

Any ideas? Has the RGBM model changed over the years to become less conservative?

any advice appreciated

Ian


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[Rand]

I can't advise if the algorithm has changed or not, but I'd take a look at the PPO2 settings. Maybe hers is set to allow a higher PPO2 than yours.

 

[RonR]

Suunto’s implementation of the RGBM algorithm might have changed some over the years, but it is proprietary and there isn’t any way for someone not privy to the inner workings to tell.


At what depth range you are seeing this 10-15 minute difference in NDL’s? Very slight differences in algorithms could create large differences expressed in minutes of NDL at shallower depths, since NDL’s are taking an analog process and expressing it as a binary outcome.

 

[Smudger]

Hi we are both diving in air so PP02 should be the same. With regards to depth I've noticed it between 18 and 22 meters. We did some deeper dives yesterday around 30 meters but we're ascending before it became an issue so not sure what her computer was reading. The difference in computers is amazing. The other day we were diving with an Italian couple. I think using Mares computers. I know that on the first 2 dives they were down deeper and longer, yet on the third dive I was in deco 5 mins the guide had 12 mins deco and back on board the Italian chap said he was no where near bottom limits. Makes you wonder who has it right.


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[Diving Dubai]

My opinion not necessarily fact!

The lower priced computers tend to always err on the side of safety for NDL - while they may use the same algorithm the internal software can be more conservative. This I believe may be because entry level computers are brought by newer divers and thus tend to err on the side of caution.

I have a Cressie Leonardo. Good first time computer - I dived it for 170 dives before I converted to my Suunto Eon. For a number of dives I took both as a point of interest (although dived to the Eon steel)

With both on default conservatism on dive 1 there wasn't much between them - although I was diving reefs so went deep and slowly ascended (rather than a square wreck profile) The Cressie lagged behind in re evaluating the NDL

On a multi dive trip by dive 5 the Cressie showed 20 minutes less NDL than the Eon.

I'm not sure if my Eon uses the gas consumption from the AI and adds that to the calculation.

 

[RolMar]

Hi,

Isn't the D4i air integrated? Does your wife dive air integrated? This may explain differences in NDL; your wife has probably a good air consumption and breathing behaviour.

RolMar

 

[BRT]

Hi,

Isn't the D4i air integrated? Does your wife dive air integrated? This may explain differences in NDL; your wife has probably a good air consumption and breathing behaviour.

RolMar

What does breathing have to do with NDL's?

 

[tursiops]

What does breathing have to do with NDL's?

Nothing. But it has everything to do with "air time remaining" on an air-integrated computer. The display usually shows whichever is the limiting time at that moment, for the depth you are at. Sometimes it is NDL, sometimes it is air remaining.

 

[BRT]

Ahhhh! More confusion! Guess I'll avoid that.

 

[dmoore19]

The display is labeled ATR or NDL. The lesser time is the one controling.