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Reaching deco quickly
Posted by: Manohulu ()
Date: June 02, 2019 10:26PM

Hello there,

I upgraded my OSTC3 to the latest version when it was released, but since I found out that my dives are reaching the deco quickly than before and also comparing with other buddies who have OSTC or other brand.

I checked my GF with my wife, 30/80 for me 40/80 for her, but even changing this parameter I can't stay as long as she can do.

Any advices?
Thanks

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Ralph ()
Date: June 03, 2019 07:35AM

Hi,

what's your setting on the Saturation & desaturation factors? If using GFs, they should be set to 100% each, else you get an extra penalty (shorter NDL, longer deco).

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: June 03, 2019 08:23AM

Hi ralf,

Both saturation set to default, 100%
I reread the manual to be sure I didn’t made a mistake.
As I wrote only GF are set to 30/80 and also tried 40/80 as my wife has.
But she don’t have OSTC, I’ll check with a friend this afternoon who has a OSTC, during the next dive.

Cheers

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Kehrmaschine ()
Date: June 03, 2019 01:13PM

Hi

A higher GF low won‘t make a big difference. Just the first Deco stop will be shallower.

Best regards
Mario

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: June 19, 2019 02:24PM

Sorry for the late answer, it can be from a poor battery. During the dive I saw a battery warning but soon I finished it my battery percentage increase to 72%. one hour later, 26%...
Battery changed let see next dive.

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Ralph ()
Date: June 19, 2019 05:57PM

Well, as long as the OSTC stays alive, it will do its calculations in a propper way...

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: June 19, 2019 07:18PM

I may have a big issue since 3.01 update

It worked fine for the update one month ago, but now, I put a brand new SAFT LS 14500 and it's written Batt:0% ; In system information I have 3.445 (T0)

Another thing is when it reboot (batterie replacement) it's written Successfully Update to 3.01, but every time.

So I would try to reflash my computer but I can't connect to it on OSTC Companion 3.00 beta 8 I got this message:
OSTC3 selected.
Connecting...
Bad identity reply (1)
Port tty.usbserial-A4SHCQSJ: Bad identity reply (1)
Error: Port tty.usbserial-A4SHCQSJ: Bad identity reply (1)

Any idea...

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: June 19, 2019 08:11PM

So I did a reset battery and re set to T1 3.6v disposal, all back to normal, 100%.
Also reflash from my Linux computer instead of Mac, connection OK, I could reset all things.

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: July 13, 2019 12:12AM

I remove GF from the algorithm and all went back normal...

Did something change? I always had GF since I have this computer.

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Ralph ()
Date: July 13, 2019 04:58PM

Within the last and current release versions 2.99 and up, nothing fundamental has changed with the deco algorithm, including the GFs. Only the 3.03 published as beta has largely refactored code, but it is not recommended for productive use yet. Actually, there will be an updated beta soon.

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: July 13, 2019 05:27PM

Thanks Ralph,

I don’t remember which version I had before the one a have but probably before 2.99.

Anyway I don’t think GF are very useful for recreational dive, just have to remember to re add it soon I’ll have to do technical dive with deco tanks.

All the best.

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Ralph ()
Date: July 14, 2019 12:01PM

Well, without GF and with Sat/Desat at 100%, staying a little bit away from the absolute NDL limit would be wise. Doing the safety stop will help in doing so. Alternatevely, you can also set the Sat/Dsat to say 95% as these factors where on purpose introduced to add conservatism in a none-GF regime.

BR
Ralph

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Re: Reaching deco quickly
Posted by: Manohulu ()
Date: July 14, 2019 07:19PM

Hi Ralph,

Set the Sat/Dsat to say 95%, heuuu my lower value is 100% and up to 140%.
GF are, but not activated
Low 30%
High 80%
I’ll try with my buddy who have a OSTC 2n with GF disabled just to see some adjustments.

Thanks,
Manu

OSTC3 #2315 v3.01
Switzerland

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Re: Reaching deco quickly
Posted by: Ralph ()
Date: July 15, 2019 07:45AM

Hi Manu,

sorry, 95% for Sat was in error from my side, it would be 105% for this value. So: calculated saturation taking place 5% faster than in "real" and desaturation 5% slower than in reality.

There is a lot of debate on which GFs to set, with current bias to set the GF low not too low. If you are air diving with going into little deco only, a GF low of 30% is probably not working well, values in the range of 50 or even 60% are increasingly belived to be more appropriate. A GF high of 80% will do quite good, giving some safety margin. Just for comparison: other brand's "sport" computers, although not providing possibility for GF adjustment and/or not using Bühlmann but some other algorithms, seem to do things that can be matched with Bühlmann on a 90/95 GF setting...

BR
Ralph

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