That cuts both ways: just because we don't know the full facts doesn't mean the full facts would exonerate the computer. Purely hypothetically, having no awareness of the cressi, the OP may have been diving nitrox with his backup on air, and so by that dive in the multi-day schedule, the backup was ridiculously wrong. You'd have the operator failure rather that computer failure if this were true, but the number on the computer screen is still wrong.
Backup Computer went into Deco
- Thread starter DON-PNW
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That cuts both ways: just because we don't know the full facts doesn't mean the full facts would exonerate the computer. Purely hypothetically, having no awareness of the cressi, the OP may have been diving nitrox with his backup on air, and so by that dive in the multi-day schedule, the backup was ridiculously wrong. You'd have the operator failure rather that computer failure if this were true, but the number on the computer screen is still wrong.
I only need couple of s to check my back up which is on the other arm. It does not make any sense to leave the back up eg. in the pocket and forget about it. The poor thing might have other ideas during the dive eg. pop out for a free dive, closed down for a rest. I do not want a situation that when I need the back up and it is NOT there to offer any help.
I do believe if the OP has paid as much attention to his/her back up as his/her primary during the dive, he/she would had noticed the big discrepancy and acted accordingly.
I do believe if the OP has paid as much attention to his/her back up as his/her primary during the dive, he/she would had noticed the big discrepancy and acted accordingly.
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DevonDiver
N/A
We don't know the full facts, therefore it's impossible to disregard the scenario that a multi-day diving schedule could have obligated this deco.
I once had a surprising 24 minute deco obligation from a dive where I left the bottom (16m) having only gone into deco by 1 minute. I ascended (too) slowly and the deco accumulated very rapidly throughout the ascent. This wasn't an algorithm (Suunto RGBM) glitch, it was because I was at the tail-end of a very intensive multi-day series of deep (no-stop) dives.
I've done intensive recreational dive trips where I was entering the water in the morning with slow tissues saturated ~70% (as per SDM logs). Those tissues can easily become ascent controlling, and that would lead to big deco, very quickly... a deco obligation that'd rise on ascent.
The goal isn't to prove guilt or exonerate either the dive computer or the diver. I'm merely stating that further information is required, accounting for the full dive history, to give a clearer indication of how the deco was created.
Likewise, if the diver had maintained awareness of the gauge throughout the dive, we'd have a clearer indication of any equipment factors that may have caused the deco to arise... such as a faulty depth sensor reading. We'd also know the initial no-stop time given by the computer, when it entered deco and how that deco manifested during the ascent.
However, we know none of that.
K
KeithG
Guest
This conjecture would be more plausible if at least 1 of the other dive computers also went into deco.
DevonDiver
N/A
If we ASSUME that every dive computer did every dive identically in the days leading up to that specific dive.
I'm not sure what's so hard to comprehend.
Four people meet in a restaurant for an early lunch and each orders a light salad. Three of those people eat their salads quickly. One person takes a few mouthfuls and puts down his fork, explaining that he's full.
Was his salad somehow different?
Or did the guy actually just eat a heavy brunch shortly before meeting his friends for lunch? (and neglect to mention it)
K
KeithG
Guest
Occam's Razor.
oldschoolto
Contributor
I wish that the OP would give us a few more details...
Jim...
Jim...
K
KeithG
Guest
That would make life way too easy.
The part where it was the backup computer and so at least one other computer (the primary) should have done every dive identically in the days leading up to that specific dive.
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The OP @DON-PNW has not been in the thread since day 2, post #22. As much as we'd all like to see the downloaded profiles and dive details from the Cressi and Mares computers, it doesn't seem very likely.
With very little to go on, there has been considerable speculation. It seems nearly certain that the Cressi malfunctioned and/or was set differently than the OP thought. There were 6 divers doing a similar profile, appears that only the Cressi backup of the OP went into decompression, very lengthy at that. It seems unlikely to me that the Cressi RGBM decompression model is terribly different than the Mares version. Both are regarded as relatively conservative in repetitive dive testing and perform similarly.
The OP stated it was an air dive and that no personal safety factor had been added to the Cressi. The setting of the personal safety factor can be confirmed in the routine computer log, secondary screen. There was no mention if this freshwater lake dive was at sea level or altitude. The Cressi Leonardo does not automatically adjust for altitude and must be set via the menu. The altitude setting for this dive may have been inadvertently set higher than the actual dive. The altitude setting can also be confirmed in the computer's routine log, main screen. I have no good idea if an incorrect personal safety factor and/or altitude setting could generate the very large decompression discrepancy described.
It is also possible that there was a malfunction of the computer's pressure sensor. Since it is a backup, no harm would be done by taking it on another dive after all settings are confirmed, paying more attention to its performance. If it continues to malfunction, the computer could be taken to a Cressi dealer or sent in to Cressi for evaluation.
Regardless, it would be great to have a conclusion to this interesting story
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