Are Suunto Zoops super conservative?

[tursiops]

Because you cannot reproduce multi-level dive profiles in planning mode

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Of course not.
But would they have not made their same point more directly and simply and understandably and reproducibly by using a single-depth (square) profile?

 

[scubadada]

DAN project dive exploration has collected a lot of data, I hope they will publish soon. There is a small chance they will be able to differentiate between decompression algorithms and risk of DCS. Intuitively, the longer you spend at depth, the higher your risk of DCS. Even the most liberal algorithms may be so safe as to preclude being able to demonstrate a difference. I have in excess of 1400 safe dives running DSAT, what does that say other than my own personal experience?

 

[Umuntu]

Of course not.
But would they have not made their same point more directly and simply and understandably and reproducibly by using a single-depth (square) profile?

So ... you are suggesting that they use a totally unrealistic and unrecommended see-saw profile so numbskulls who cannot read a very legible graph can find another reason to criticise it ?

 

[tursiops]

So ... you are suggesting that they use a totally unrealistic and unrecommended see-saw profile so numbskulls who cannot read a very legible graph can find another reason to criticise it ?

Who said anything about a see-saw profile?
I suggested a square profile....you know, down, stay on bottom, up. Like a table uses.
More importantly, the point is to design a typical set of profiles, say three a day, or five as you might do on a liveaboard, and then compare the computers. If you want to show your computer is better (I assume that is what Oceanic wanted to do) then you'd do more than a single dive, so the real differences can begin to show.

 

[Umuntu]

DAN project dive exploration has collected a lot of data, I hope they will publish soon. There is a small chance they will be able to differentiate between decompression algorithms and risk of DCS. Intuitively, the longer you spend at depth, the higher your risk of DCS. Even the most liberal algorithms may be so safe as to preclude being able to demonstrate a difference. I have in excess of 1400 safe dives running DSAT, what does that say other than my own personal experience?

I doubt it. The dive computer companies would threaten legal action. And its really not worth it for the sake of getting the statistics out there.

What is implied is that those DCs which produce super-liberal repeat dive NDLs are the ones most suspect in those 41% of DCI incidents within NDL limits.

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[Umuntu]

Who said anything about a see-saw profile?
I suggested a square profile....you know, down, stay on bottom, up. Like a table uses.
More importantly, the point is to design a typical set of profiles, say three a day, or five as you might do on a liveaboard, and then compare the computers. If you want to show your computer is better (I assume that is what Oceanic wanted to do) then you'd do more than a single dive, so the real differences can begin to show.

a multi-level profile is a more typical dive profile.

I view a square profiles as similar to a see-saw profile.

There is nothing intellectually or statistically wrong with their graph !

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[scubadada]

...What is implied is that those DCs which produce super-liberal repeat dive NDLs are the ones most suspect in those 41% of DCI incidents within NDL limits.

You have no evidence to support that whatsoever

 

[yle]

The most recent BSAC Diving incident report 2017, page 4 says :

1. Decompression incidents
   
   The BSAC database contains 56 reports of ‘DCI’ incidents in the 2017 incident year, some of which involved more than one casualty. An analysis of the causal factors associated with the 56 incidents reported in 2017 indicates the following major features:-
   
   45% involved diving to deeper than 30m
   41% were within the limits of tables or computers
   41% involved repeat diving
   11% involved rapid ascents
   7% involved missed decompression stops

BSAC does not publish details of the DC involved . I understand that every year hundreds of thousands of incident free dives will be done on all brands of DC. But at the margins, which DC brands are involved in those DCI incidents?

No doubt there were probably more "liberal" DCs involved with these incidents than there were "conservative" computers. But that doesn't mean that the "liberal" DCs do not work. There are two issues I see with the stats you post here:

1. "DCI" generally refers to decompression issues and lung overexpansion issues. The dive computer would generally only be able to address the former. That is, a dive computer has no idea when someone is holding their breath on ascent.

2. The fact that 41% of incidents occurred when the dive computer says they should not have is simply evidence for the importance of secondary factors that influence the particular risk of individuals. The dive computer can only calculate according to the risk represented by the settings chosen by the operator. If a dive computer shows the diver should be okay but the diver is hit with DCS, then by definition there was a secondary risk factor that the computer (and perhaps the diver also) was not aware of.

Neither of these two points makes any dive computer less reliable. In fact quite the opposite: the 41% only shows that divers need to be taught to be aware of how their computers work, what information the computer needs to operate properly, and how the diver should use the information provided by the computer to make decisions to minimize risk to their health.

 

[tursiops]

a multi-level profile is a more typical dive profile..

Agreed, that is often true. So do a series of multi-level profiles; my point is to do a series of repetitive dives, not just a single dive, if you are going to show the differences between algorithms/computers.

I view a square profiles as similar to a see-saw profile..

Seriously? So you feel all dive tables are nonsense, since you view see-saw profiles as nonsense?
I hope you are just being contentious for the fun of it, and don't really mean what you said.

 

[Umuntu]

No doubt there were probably more "liberal" DCs involved with these incidents than there were "conservative" computers. But that doesn't mean that the "liberal" DCs do not work. There are two issues I see with the stats you post here:

1. "DCI" generally refers to decompression issues and lung overexpansion issues. The dive computer would generally only be able to address the former. That is, a dive computer has no idea when someone is holding their breath on ascent.

2. The fact that 41% of incidents occurred when the dive computer says they should not have is simply evidence for the importance of secondary factors that influence the particular risk of individuals. The dive computer can only calculate according to the risk represented by the settings chosen by the operator. If a dive computer shows the diver should be okay but the diver is hit with DCS, then by definition there was a secondary risk factor that the computer (and perhaps the diver also) was not aware of.

Neither of these two points makes any dive computer less reliable. In fact quite the opposite: the 41% only shows that divers need to be taught to be aware of how their computers work, what information the computer needs to operate properly, and how the diver should use the information provided by the computer to make decisions to minimize risk to their health.

1. Read the Report. It breaks down lung over expansion issues separately.

2. I agree on the individual risk factors. But the exact correlation between repeat dives and within NDLs says something.

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