Another bugs in the dive computer

sagit

Hi All,

I am a new guy as I bought suunto nautic together with my buddy.
We diving a technical way.
Unfortunately the computer is not relevant for a technical dives as suunto put some extra things on NDL time, Deco time etc.
As a primary I am using Petrel 3 Shearwater.
I made identical settings on both computers and despite that on e dive for 25 meters max with small deco on air 14 minutes on Sharewater Nautic showed me 70 minutes.
On a both suntos was the same.

That is not a technical diving computer.
I feel cheated by Suunto, they should say, yes we have put Buhlman but added something extra. Fine. I wouldn’t by it then.
Now i stuck with this computer, I cannot trust anymore.

As a whole the computer is great, batery life, screen fabulous, compass. But it needs to follow to buhlamn like other brands.
I have checked with my buddys computers, all on, two nautic and marrs genius, shearwater petrel 3 and peregrine as well.

For me there are only two options. Suunto realise firmware upgrade and let us to decide what we want or give money back.

Regards
Chris from UK

hhouter

@sagit hi chris, Gf High and Low are the same on both?

nico5710

Hi Chris, hi all

I am seeing the same behaviour with my Suunto Nautic.

After comparing actual dive profiles with standard Bühlmann ZHL-16 calculations using similar Gradient Factors, the main issue is not just that the Nautic is more conservative: the difference seems to increase significantly with depth and decompression load.

In my observations, below roughly 30m the discrepancy remains relatively limited, but beyond about 40 m it grows very quickly with depth and bottom time. The decompression curves therefore do not appear to remain parallel between a conventional Bühlmann implementation and the Suunto implementation.

I am not enough of a decompression-model specialist to explain which compartment, ceiling calculation or additional conservatism is responsible, but the behaviour looks like more than a simple fixed safety margin or small implementation difference.

Unfortunately, I discovered this during an actual dive, and the unexpectedly long decompression created additional difficulties during the ascent with other buddy in normal Bulhman algorithms

This is particularly frustrating because, apart from this, I find the Nautic excellent in terms of display, ergonomics and general usability.

For my type of diving, however, this behaviour makes it very difficult to use once entering the 30–60m range with significant bottom time.

I therefore really hope Suunto can explain precisely how their Bühlmann implementation differs from a conventional ZHL-16 + GF model, and provide a firmware update or setting allowing behaviour closer to a standard Bühlmann implementation.

Otherwise, despite really liking the computer, I would unfortunately have to replace it.

Regards
Nicolas from FR

sagit

@nico5710
Hi

That is what I said to Suunto but they are pretending to know nothing about that.
Classic big companies behaviour.
That way people like me will spread that information and no technical diver will buy it.

Would be enough to creat a profile called oc tech which automatically change it for clear algorithm like in Shearwater and works fine.

Suunto did not mention about additional conservatism and pretend that ot doesn’t exist.

Nandodiver

Actually I have scubapro luna that has 2 deco algorithm and one of them match the Nautic & Nautic S

None of this 3 computers are referenced for technical dive, or are sold to be technical dive computers, but rather advanced recreational dive computers

Dived up to 50/55m several times without issues.

To be honest with more than 400 dives, doing 14 minutes of deco on air at 25m (seems excessive for my standards), I would not call it “small deco” but I would use Nitrox 32% and would enjoy more bottom time than deco time…

Also the Petrel from factory has GF of 99/99 and can be changed to 30/70 (Tec) e 40/85 (Rec)

Suunto computers traditionally penalize rapid ascents or erratic depth profiles heavily. If you or your buddy experienced a brief, fast ascent earlier in the dive, the Nautic may have applied an aggressive microbubble penalty that instantly reduced its remaining NDL time, while the Petrel 3 calculated the tracking strictly linearly based on current depth and time.

**ZHL16D+MB (scubapro algorithm)
ZHL16C-GF
GF 40/85 medium
last safety stop 3m
ppO2 Max 1.6 (for deco only )

Nautic GF 40/85 medium conservatism
Nautic S GF 40/85 medium conservatism
last safety stop 6m
ppO2 Max 1.6 (for deco only )

The Petrel 3 Shearwater uses ZHL-16C
The Nautic/Nautic S uses Bühlmann ZHL-16C model that have implemented their own code.**

Suunto Nautic is using Suunto’s Bühlmann 16 GF dive algorithm that is based on the Bühlmann ZHL-16C model that we have implemented our own code for

https://www.suunto.com/Support/Product-support/suunto_nautic/suunto_nautic/algorithm-settings/buhlmann-16-gf-algorithm/

Nandodiver

@sagit

Hi suppose at 25m dive to get 14m of deco on air your dive lasted 50 minutes including the descend…

With normal SAC of 20L/m you had to use twinset or sidemount tanks of 12L/200

With low SAC of 15L/m the 12L/300 bars is enough but violated the rule of third in technical diving

Are you sure you didn’t made some confusion with TTS number, because does 70 minutes deco are irrealistic.

Ive ask AI how much bottom time, would need be needed to get deco of 70 minutes on Suunto using GF 45/95

**To force the Suunto Nautic algorithm to generate this specific requirement, your bottom time must be extended to an incredible 180 minutes (3 hours).

The exact calculation of the Total Dive Time (TDT) and the chronological profile result in the following values:

Total Dive Time (TDT) Timeline BreakdownBottom

Time (including descent): 180 minutes
Ascent Travel Time (to first stop at 9m/min): 2 minutes
Mandatory Decompression Stops: 70 minutes
Final Ascent to Surface (from 3m): 0.5 minutes

TDT =180min +2min + 70min + 0.5min = 252.5minutes

Your Total Dive Time will be 4 hours, 12 minutes, and 30 seconds.**