INSTRUCTION FOR USE DECO MODE

[guyloup]

Hello,

I have the following info on my instruction for use ( OSTC Sport red buttons). in addendum.

I was diving with my computor with GF 30/80 and decided to take a more conservative approach and select the more conservative Saturation factors 85%/115%.

What surprised me is, when tested on OSTC Planner, the conservative Saturation factors looks to be LESS conservative than the GF 30/80 when your instruction for use says the opposite.

CAn you explain this? Thank you.

[heinrichsweikamp]

Hi,

Sorry, I did not understand this question. Some points you mentioned do not add up correctly (Conservatism 0 is GF30/80 or 88%/112% for non-GF deco mode). 85%/115% is Conservatism +1, in GF mode 20/75.

Regards,
Matthias

[guyloup]

Hi MAtthias, thank you for answering.

What I mean is that is that non GF 85%/115% seems to be LESS conservative than GF 30/80. If you look at the graph from OSTC Planner the first one (85%/115%) gives you no deco stop while the GF 30/80 gives you deco stops for a 50 minutes dive @ 18 m. gas= air.
,
the purple line is GF 30/80, the red line is non GF 85%/115%.

[heinrichsweikamp]

Interesting question: What is less conservative? You can't really compare non-GF deco with GF deco. And yes, non-GF deco assumes GF hi and lo of 100 and applies these saturation/desaturation multipliers instead.

Honestly: Do not use non-GF deco. It's outdated and has it's weaknesses especially for repetitive dives.

Regards,
Matthias

[guyloup]

Thank you MAtthias. Guy. When you make a revision of the instruction for use, I suggest that you draw attention to what you are saying.

For your information, I am raising all these questions because I got an ADD by switching my computor from GF 30/80 so saturation 85%/115%, thinking that I was going safer. The ADD resolved itself in a few hours under oxygen, and I have no consequences. I am not saying that I had one because of the settings, I am just trying to say that your wording is a bit misleading.

[heinrichsweikamp]

Hi,

Just as a comparison, the trusty old Uwatec Aladin computers used 90/110. Speaking in modern terms: Insanely aggressive deco and still a lot of dives made with these computers went just fine.

Stick to the conservatism setting. A setting of +1 or +2 makes the computer more conservative. I absolutely know nothing about your deco accident but if you are interested in some very basic feedback (Only about the computer and the profile) please post the profile here in the OSTC Tools format and we can have a look if any obvious errors are visible. I have seen profiles of diving accidents where one diver died due to deco sickness and the other one (With the exact same (catastrophic) profile) had no signs at all. So I'm afraid it's a bit too simple to say that a slightly more conservative setting would have prevented that.

Hope you are fine again, of course.

Regards,
Matthias

[guyloup]

Dear MAtthias,

I hope that you understood that I am perfectly fine and I do not attribute the problem to the change in the settings. If I did so, I apologise. I am just trying to say that I would be more careful in the wording, should I edit the instruction for use. So do not worry. My profile is enclosed. Even @ GF 30/80 it shows barelly a saturation . I came back from a visit to an hyperbaric doctor. The suspiscion is a FOB and a too slow ascent. No worry. Thatnk you for your honnest approach. Everybody appreciates this. FYI is was dive # 11 in 4 days, 3th dive of the day.

[heinrichsweikamp]

Hi,

Don't worry, I have understood your point. The profile looks fine, impossible to say what went wrong here without the detailed medical investigation. But it's a good thing that you went to the doctor. Others would have threaded this by themselves with some O2 and kept on diving...

regards,
Matthias