Strange value for future TTS

[s_dem]

Hi,

i had a strange problem with my OSTC2, Firmware 2.70 on my last dive.

Diveplan was: Doing some drills at about 5 Meters for +/- 10 minutes. Then going down to 42 meters, 20 minutes bottom time. Gases used were: Air for the beginning, bottom and ascend to 21 meters, then switch to EANx at 21m and 100% oxygen a 6 meters.

After about 12 minutes at 42 meters, TTS was about 12 minutes, which seemed right. However, future TTS (5 minutes in the future) was 9' which is simply not possible. I then switched through the fields with the right button, because i wanted to find out, if it is "simply" an update problem. However, after switching through the fields and coming back to future TTS, the computer couldn't calculate the future TTS anymore and showed "---".

any ideas?

best regards,
Steven

[dogster]

Hello,

I have same problem, no matter what my overall TTS is and no matter how my gaslist is set up, my future TTS shows max. 9’ for @+5min, even when my TTS is 30’ or more. Sometimes it won’t show future TTS at all, it just shows --- for @+5min. If anyone knows the solutions please reply.

[heinrichsweikamp]

Hi,

This seems indeed a bug that only occurs in the "OSTC 2C" hardware (New display).

We'll add this fix to the next official release, of course.

Regards,
Matthias

[dogster]

Thank you for your quick reply and HEX code solution.

Today I have updated the firmware of my OSTC 2C and in simulator mode looks like it is working OK. I still have to test it underwater but am counting on smooth operation of my OSTC.

For all of you that would like to solve this problem there is a 2.74 BETA Firmware attached to this post that you can update through Weikampbootloader.

[kaheksa]

My future TTS just shows "---" no time

[heinrichsweikamp]

Hi,

This issue has now been fixed in the new 2.74:
http://www.heinrichsweikamp.com/?id=57&version=en

Only OSTC 2C were affected from this bug.

Regards,
Matthias

[Bardass]

Not working for me :

Mix : Air
Depth : 60m
Bottom time : 10'
TTS : 23'
TTS + 5' : 51'

Up to 20m
TTS : 15'
TTS + 5' : 14'

Up to 10m
TTS : 15'
TTS + 5' : 10'

[heinrichsweikamp]

"TTS+5" can be lower then your TTS if your tissues are desaturating.

Regards,
Matthias

[Bardass]

i know
but i don't think so if i stay 5 minutes more at 20m

in fact, it depends how we have to read Future TTS

if future TTS + X' = Y',
Does it mean :
future TTS = X + Y minutes
or
future TTS = Y minutes including X minutes

[sailor]

Hi Bardass,

When you stayed for 10 minutes at 60 meters, you are for sure desaturating at 20 meters, even after 5 minutes.

What times are you referring to by x and y?

Reiner

[Bardass]

I'm desaturing for sure
but much less if i join the surface

if i stay 5 minutes more at 20m, my future TTS can't be less than my actual TTS

[sailor]

Yes it can, when the dive was quite deep and your tissues are desaturating at 20 meter.
In that case your time spent at 20 meters is actually a deco stop.
The time you are staying on a deco stop will reduce your TTS.

The same will happen on shallower deco stops.
When you arrive to 6 meter from a deeper dive with a deco obligation, your TTS might be for example 12 minutes with a 5 minutes deco stop at 6 meters.
Your future TTS + 5 will show in this case 7 minutes with an actual TTS of 12 minutes.
The same might happen on 20 meters after a deeper dive, if your average tissues are desaturating.
Then the time at 20 meters count in as a deco stop and the same systematic will happen but you will not see a deco stop on your computer necessarly.

[s_dem]

bardass, i think it means "future TTS = X + Y minutes".

so, if you have TTS + 5 = 14', it means in 5 minutes, the TTS will be 14', in total 19 minutes from now.

As for the change of TTS on 60m, this seems a bit extreme to me. Is your bottom time inluding the descent or is it "real" bottom time?

[Clownfish]

It seems to me that the 51 minutes TTS indicated in the TTS +5 when still at 60 m is about right. From experience, I know that for every minute at 60 m after you hit deco you gain about 5 mins deco. Therefore, at 10 mins current TTS is 23 mins. Therefore, for TTS +5, add another 5 x 5 mins = 25 mins which gives 48 mins, very close to the indicated 51 mins.

As others have indicated, when you ascend and start off-gassing, the TTS +5 should always be less than the current TTS, even though it may only be a minute or two (indicating that you are not off gassing very fast). You in fact may be gaining more time at shallow stops while getting rid of deeper stops.

Once at your correct depth for stops, it should show 5 mins less for TTS +5 comapred to TTS.

[Bardass]

you don't understand what i mean :
TTS means Time to Surface. It includes ascent time + deco stop based on actual time.

So, with same deco stop for normal and future TT, if i stay 5 minutes more (Future TTS +5), i should get surface at least 5 minutes later

For example, with the same deco stop at 20m (ex 12')
TTS is : 3' to ascent to surface + 12' deco stop = 15'
future TTS + 5 must be for me : 5' more at this depth + 3' to ascent to surface + 12' deco stop = 20'.

Don't tell me than 5' more at 20m decrease deco stops from 12 to 6' at 20m as i shown in my simulation above (with air mix) ...

[Clownfish]

TTS +5 does not include in its calculation the 5 mins from now till then. It is what the OSTC will show in 5 mins time. For example, if you have TTS of 10 mins now and you are accumulating deco of 3 mins for each minute you stay, the TTS +5 will show 25 mins (that is, original 10 mins + 5 x 3 mins).

I hope this explains it.