is my computer trying to bend me ?

[liamm]

Just spent a week in the red sea - superb, the highlight of which was the thistlegorm. I was diving with a mate who was on a sunto D6 and i was on an alladin smart pro (18months old).
Most of the profiles were fairly conservative - about an hour run time fairly shallow and the last twenty mins spent at 10m or less. On the last dive on the thistlegorm we spent a bit of time at 28ish nosed about and then got gradually shallower as we worked throuigh the wreck. after about 40mins we had worked up to 20m and my comp was still allowing me 30min no stop time, my friends d6 had 12 mins left and the guide had 8mins. There wouldnt have been much of a difference in profiles between us and we were all on 31% - is there a problem with the computer or does this seem normal?

I had intended on selling it and getting something that could do three mixes but i'm now unsure about selling it if its not working.

Ant help appreciated

[Mal Bridgeman]

It is not trying to bend you .... there is of course no actual link between the calculations they are doing and the likelihood of you getting a bend.

So if you accept they are just posh calculators, then each one is basing its calculations on different assumptions. There is no way of knowing which of the three's assumptions more closely matches the reality of your personal circumstance.

There is a belief that choosing the most conservative must be a good thing .... but it still does not accurately reflect what's going on physiologically.

HTH
Mal

[weazelz]

had you done all the previous dives with those buddies too? it sound to me like they were carrying some residual nitrogen & were being penalized

[liamm]

the guide may have been carring residual from different days but my buddy and i were the same for four days previously.

mal i get what you are saying, i'm just interested to know whether this difference between uwatec and suunto is normal or is it outside of normal variance. 18 mins does seem to be quite a lot.

[Mal Bridgeman]

Originally Posted by liamm

the guide may have been carring residual from different days but my buddy and i were the same for four days previously.

mal i get what you are saying, i'm just interested to know whether this difference between uwatec and suunto is normal or is it outside of normal variance. 18 mins does seem to be quite a lot.

Agree 18 mins on a 40 min dive does seem a lot.

I haven't done direct comparisons but I always think the Suuntos are very conservative. There are other variables which affect the calculations like the personal conservativeness setting.

I have observed before that the Suunto would show 0 mins NDL well before the Oceanic Computer I used to wear, would....even on a 0 conservatism setting.

Mal

[TonyD]

It's always a problem when your buddy has a different computer - my Cochran Commander will always clear about 8mins before the wife's Suunto - but unless you and your buddy are joined at the hip for the whole dive, if you both use the same make/model of computer you will quite often get different deco times. I think your Aladin will be using Buhlman tables and the Suunto RGBM, so will be different.

Glad you enjoyed the trip.

[John63]

There willl always be differences between brands, and also dive buds computers. Although you have been diving together for several days, you will not have had exactly the same profiles. eg did one of you dip a little deeper, ascend marginally quicker etc. The only way to compare directly would be for 1 diver to wear both on the same wrist throughout the series of dives.

I use Uwatec (pro ultra and smart tec) so can't comment on the Suunto, but a mate of mine has a Stinger and Aladdin Air Z which he wears on the same arm and does notice differences though I cannot recall magnitude.

I get the impression from him that the Suunto is quite punative on repetative dives, especially where the surface interval has been short, though as I have said this is anecdotral as I haven't personally used one.

If you are diving conservatively within NDL, and with longish safety stops to offgas I wouldn't have thought there was a problem. Bear in mind that teh front of all dive computer manuals has a disclaimer that states there is no guarantee of avoiding DCI and that the bow of electronics on your wrist is for guidance only. The ultimate cop out clause.

Cheers, John

[Finless]

Just email the dive stats to your manufacturer's support team and advise them of your concerns about the differing "no stop times" between your computer and others being used.

[Finless]

Do those computers have the facility to set your own 'level of conservatism(is that the correct word to use)'? If yours is set to nil and the others are on 10% or 20% then with repetitive dives then perhaps that would explain the difference ?

[al kennedy]

Originally Posted by Finless

I assume your concern is not that your computer is now giving you

I hate being left in suspense...