Deeply Safe
LABORATORIES
language
Can you trust your dive computer?
Deeply Safe Labs will try to bring an answer to that question. It is possible that it won't seem satisfactory to you, it may not even please you.
What you won't find here are rankings, review or grades, rather verifiable facts and transparency. That way we hope that you can build your own opinion, still you will need to take a step back and avoid any coulding in your judgment.
March 2024 update : Taking your numerous comments into account and trying to help you build that opinion, we made a guide to reading the results. Use it to reach further comprehension, if you wish so. We encourage you to check each test details for more precision. We keep on listening to your remarks. We recommend registering to our newsletter.
What traps are to be avoided?
e mindful, we all tend to believe what is convinient to us and favor hypothesis and informations that confirm our ideas and do not contest our beliefs
No one does such dives, these profiles are completely out of touch!
A few minutes of stop time can make the difference between an unforgettable dive and decompression sickness (DCS), but to make comparisons, significant amounts are necessary. Studying the behaviour of a dive computer at low depths or with ridiculously short times would be of no interest.
This certainly does not mean that the risk would be absent with shallower, shorter dives, with longer surface intervals or even, and maybe worse, within no decompression times.
Why chose such short surface intervals? Everyone know it's dangerous!
Testing a computer behaviour on multiple dives with intervals of 3, 4 or 6 hours is just as useless. With a long interval, the physiological phenomenum due to previous immersions becomes negligable and risk is lower.
There again, going overboard is necessary. If your computer's algorithm reacts correctly to a "heavy" profile, maybe you can trust it for real dives.
I've been diving with a "Straightothechamber" computer for more than ten years, and I've never had DCS!
If a computer was dangerous, it would be public knowledge, wouldn't it?
High caution is required in interpreting DCS statistics
• No study permits correlation between the number of DCS and number of immersions,
• There exist no data regarding the table or computer model used during a dive that led to DCS.
Emergency and rescue coordination services don't bother with the later, that's not their purpose.
Any conclusion would then be hasty and hazardous.
Even if these data were processed, a study would find it difficult to prove that a computer is or isn't safe:
• In the same buddy team, all divers rarely use the same computer. They will follow the stricter decompression schedule.
• Common sense procedures and habits most probably protect divers (slow ascent, additional or "safety" stop, staying at low depths at the end of the dive...)
Still...
On the French Mediterranean coast:
• 90 rescue operations in 2020,
• 117 in 2021,
• 155 in 2022,
2022's level was passed in september 2023!
French Mediterranean Maritime Prefect reports, in their 2023 summary, an increase by 10% of DCS occurences.
It's not the new computers that are dangerous, it's the old ones that gave too much decompression times...
No matter the subject, certitudes are rare in the scientific litterature. It is particularly the case with diving, some concepts still cause debate these days. Nevertheless, multiple studies led to knowledge that few scientists dare speak against:
• For diving with air, deep stops are considered to be dangerous and should be avoided.
• Multiple and repeating dives show particular dangerousness and should be computed with a specific and adequate procedure.
Here is what Albert A. Bühlmann wrote :
Experimental dives and statistics (DAN, BSAC) confirm a higher risk of decompression sickness for repetitive dives. Microbubbles in the venous blood obstructing a part of the lung capillaries produce ventilation-perfusion trouble, a right-left shunt well known in lung physiology.
Source : Albert A. Bühlmann, Behavior of dive computer algorithms in repetitive dives : experience and needed modifications, in Hamilton R.W. edition, UHMS Workshop 81, 6-1-1994, Undersea and Hyperbaric Medical Society.