forum.heinrichsweikamp.com

Hi all.

After five dives during the last two days, my OSTC (v.1.90) told me I would desaturate for 35h 22min until clear. This desat time is also stated in the log book for the last dive. That meant, in this case, Saturday morning at 2:55.
At 10 o’clock Friday morning it said 7h 41m left. That would be 17:41 Friday afternoon instead. At 12:35 it had 3h 11min to go and at 14:05 it was about finished, with only 12min left.
Of some reason it has shortened the desaturation time with about 12 hours.

I have seen the same behaviour after all dives. Even in previous software versions. It has never, so far, prolonged the desat time. Is this a bug or is there a good explanation?

Maybe the atmospherical pressure has changed?

Between the end of the dive and the actual end of the OSTC Desat-calculation, the atmospheric pressure dropped from 1013hPa to 1008hPa.
Theoretically these 5hPa will off cause speed up the real desaturation, since the pressure dropped even more after reaching the surface. Any way I think it’s hard to believe that a so small drop in pressure, equal to approximately sea level + 45m, will do a difference that big.

Also, I have so far never seen the Desat-time increase. Even though I haven’t followed the atmospheric pressure trend carefully, I’m sure there have also been rising pressure after my dives.

If a drop of as little as 5hPa in 24 hours equals a decrease of the desaturation time of 12 hours, wouldn’t there be a notable increase of the desat-time if the pressure rises after the dive?