Are Suunto Zoops super conservative?

[dmaziuk]

I won't go into my Math and Statistics credentials ...

Let me illustrate ones and zeroes...

 

[scubadada]

Please tell me what you think "arrival" and "departure" NDLs means in their data set.
Should I interpret your presentation of their results to mean that (for example, Dive 1, 100 ft) the NDLs are 7-13 minutes, depending on the computer? Why in the linked article do they say "Meant to simulate a day of scuba diving, the profiles were: 100 feet/55 minutes; a one-hour surface interval; 70 feet/45 minutes; a two-hour surface interval; 80 feet/45 minutes; a one-hour surface interval; and 60 feet/40 minutes." I read that as the first dive was 55 minutes to 100 ft. ?? But the NDLs were 7-13 minutes? Help.

Hi @tursiops

Using Dive 1 as an example, I believe there is descent to 100 feet, stay there for a while and then ascend to 90 feet. The departure NDL is when they left 100 feet. Then they stay at 90 feet for a while and then ascend to 80 feet.........60, 40, SS. The departure NDLs are when they leave each depth for the next. Remember, these are chamber dives, very easy to control depth, ascent rate, and time. Somewhere I read a detailed description of the dives, including time at each depth, I will try to find it again. I have been following this testing for several years. So, the 100 foot dive for 55 minutes should read max depth of 100 feet with multilevel dive for a total dive time of 55 minutes. You have the SIs correct.

 

[tursiops]

Hi @tursiops

Using Dive 1 as an example, I believe there is descent to 100 feet, stay there for a while and then ascend to 90 feet. The departure NDL is when they left 100 feet. Then they stay at 90 feet for a while and then ascend to 80 feet.........60, 40, SS. The departure NDLs are when they leave each depth for the next. Remember, these are chamber dives, very easy to control depth, ascent rate, and time. Somewhere I read a detailed description of the dives, I will try to find it again. I have been following this testing for several years. So, the 100 foot dive for 55 minutes should read max depth of 100 feet with multilevel dive for a total dive time of 55 minutes. You have the SIs correct.

OK, cool. Understood. Thanks.
So ALL the computers managed the 100 ft/55 minute ML dive?
And they ALL were able to do all four dives?
Seems like not a very discriminating test between the computers......

 

[scubadada]

OK, cool. Understood. Thanks.
So ALL the computers managed the 100 ft/55 minute ML dive?
And they ALL were able to do all four dives?
Seems like not a very discriminating test between the computers......

I agree with you, there is simply not much data on repetitive dives available. I believe ScubaLab chose dives that would not put the conservative computers into deco. As is, the Perdix 40/85 got down to 3 minutes on dive 1, the Mares and the Cressi got down to 6 minutes on dive 2, dives 3 and 4 were very easy for all. I would be interested in a more rigorous test too, but pushing DSAT or Buhl 45/95 would frequently result in putting the others in deco, perhaps that is one of the points. Even as is, there are some pretty dramatic differences between computers illustrated in the testing. I think the general trends are quite clear.

This kind of information augments the 1st dive NDLs like you, and then I, shared back in posts 135 and 154.

 

[tursiops]

I agree with you, there is simply not much data on repetitive dives available. I believe ScubaLab chose dives that would not put the conservative computers into deco. As is, the Perdix 40/85 got down to 3 minutes on dive 1, the Mares and the Cressi got down to 6 minutes on dive 2, dives 3 and 4 were very easy for all. I would be interested in a more rigorous test too, but pushing DSAT or Buhl 45/95 would frequently result in putting the others in deco, perhaps that is one of the points. Even as is, there are some pretty dramatic differences between computers illustrated in the testing. I think the general trends are quite clear.

This kind of information augments the 1st dive NDLs like you, and then I, shared back in posts 135 and 154.

I was surprised in the results to see the bouncing around a little. For example, the Cressi Goa had one of the smallest NDLs for Dive 2, but one of the longest for Dive 3. This suggests it really likes the 2h surface interval! Contrarywise, the Sherwood Sage had one of the longest NDLs for Dives 1 and 3, but was in the middle of the pack for Dive 2, suggesting it doesn't like the deeper dives.

Taking all four dives together, and rank-ordering the average results from (across four dives) the most liberal (longest NDLs) to the most conservative (shortest NDLs), the data cluster in four groups:
1) DSAT (Oceanic PPX), Shearwater AI low conservatism (Buhlman 45/95)
2) Sherwood Sage
3) Mares Quad (RGBM), AquaLung i200, SEAC JACK
4) Cressi Goa (RGBM), ScubaPro G2 and Sport, Shearwater medium conservatism (Buhlman 40/85)

And, they are all "safe."

 

[scubadada]

I was surprised in the results to see the bouncing around a little. For example, the Cressi Goa had one of the smallest NDLs for Dive 2, but one of the longest for Dive 3. This suggests it really likes the 2h surface interval! Contrarywise, the Sherwood Sage had one of the longest NDLs for Dives 1 and 3, but was in the middle of the pack for Dive 2, suggesting it doesn't like the deeper dives.

Taking all four dives together, and rank-ordering the average results from (across four dives) the most liberal (longest NDLs) to the most conservative (shortest NDLs), the data cluster in four groups:
1) DSAT (Oceanic PPX), Shearwater AI low conservatism (Buhlman 45/95)
2) Sherwood Sage
3) Mares Quad (RGBM), AquaLung i200, SEAC JACK
4) Cressi Goa (RGBM), ScubaPro G2 and Sport, Shearwater medium conservatism (Buhlman 40/85)

And, they are all "safe."

Your analysis is very reasonable and consistent with the categorizations as liberal, middle of the road, and conservative. Every diver must make their own decision based on their own diving. In my experience, decompression algorithm is not always taken in consideration when making a dive computer purchase and is a main reason for purchase regret. All of the commercially available deco algorithms are safe.

 

[loady]

I checked my mares puck pro. altitude setting is at A0.
Other then malfunction and a far more conservative algorithm what else could be causing the the big discrepensy in NDL from the Suunto?

 

[tursiops]

I checked my mares puck pro. altitude setting is at A0.
Other then malfunction and a far more conservative algorithm what else could be causing the the big discrepensy in NDL from the Suunto?

I went back and looked at some other ScubaLab tests, and some on-line comments. It appears the Puck Pro is even more conservative than the Suunto Zoop. For example, in the 2014 ScubaLab tests, the Mares computers were the absolute shortest NDLs after three "dives", except for the Cressi Leonardo.

 

[dmaziuk]

I checked my mares puck pro. altitude setting is at A0.
Other then malfunction and a far more conservative algorithm what else could be causing the the big discrepensy in NDL from the Suunto?

The question you should be asking is did you have to cut any of your dives short because of your computer? Computer-generated NDLs are like weather in Melbourne.au: if you don't like it, wait five minutes. If it doesn't limit your diving, what do you care whether the number at a given point is 99 or 15?

 

[scubadada]

Hi @dmaziuk

We have exchanged many messages. I dive my DSAT computer to the limit, or slightly over, frequently. I would be severely limited by a more conservative computer. I always wish you the best with your Cressi, maybe your RMV is the limit.

Good diving, Craig