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I have a question in regards to the maximum depth rating of the Sport and Plus model. These models are rated to 120 meter. What will the computer display / calculate at 125 meter depth?

Hi,

Officially it's 120m max.

Yes, there are some extra margins but I can't recommend using the OSTC plus in 125m, sorry.

regards,
Matthias

Hi Matthias,
My intention is not to use a device, which is rated to a certain depth, in another beyond it's limits. Interesting is to know what the reaction of the device will be if this happens. Does it give a warning? What happens with the decompression calculation?

Hi,

the first thing that will happen is the depth sensor saturating: it has an operational range of 0 - 14 bar absolute pressure. Subtractig a surface pressure of 1 bar, there will be 13 bar remaining for depth, converting with a factor of 10.19716 m/bar to 132,5 m if salinity set to 0%. With higher salinity settings, the factor reduces, i.e. the same pressure will result in less indicated meters, hence the official max depth of 120 meters. When the sensor saturates, the OSTC depth display will freeze and won't show if you are indeed deeper. Also it will calculate the deco according to the frozen depth. The deco calculation in itself could cope with higher pressure values, it is only limited by what it gets from the sensor.

With a TR model and TR functions activated, the SAC calculation may become erroneous at depths > 120 meter due to numeric overflow in some variables, but this has no consequence on any part of the deco calculation. Another optional OSTC mode that has not been released yet will not process depths > 127 meter and will therefore deliver an inaccurate deco forecast, while the actual deco data will continue to be limited by the pressure sensor only as described in the first paragraph.

The next thing to happen will be the OSTC cracking, with crush depth being depended on model (classic or aluminium housing, resin or air filled, screen gas type, ...). On top of that, each OSTC has its own tolerance limits (that you'll know only after testing), but there is sufficient margin between rated depth and crush depth. In fact, this is verified from time to time with surplus OSTCs in HWs own pressure chamber.

And yes, there is a general depth warning that is user-settable to a max of 120m. If deeper than the set limit, the depth display will start blinking in red color.

BR
Ralph

Hi Ralph,
Thanks for your extensive explanation. This covers all the curiosity.
Cheers, Jeroen

[quote]if salinity set to 0%[/quote]

0% corresponds to fresh water?
How to set this value for each salinity?

Thanks

BR

0% corresponds to fresh water? -> correct!

Important to know, the salinity setting has no infuence on the deco calculations at all, those are all done in unit of pressures. The salinity setting only tunes the displayed (and logged) depth. Increasing the salinity setting decreases the shown depth. Here's my suggestion:

lakes & pools: 0%
central baltic sea: 1%
red sea, oceans in general, western part of the mediterranean: 2%
eastern part of the mediterranean: 3%

...or if your buddies computer have a fixed setting, just set your OSTC such that your depths match...

Ralph