Petrel 2 Salinity setting

[DJ457]

This might seem like a stupid question but just wanted to make sure. The salinity on the petrel 2 comes set by default on EN13319. Should I leave it on this setting or change it to salt. I've heard of people doing ocean diving and just leaving it on this EN13319 setting.
I've been using it on the salt setting.

Thanks for the info.

 

[DuboisP]

https://www.shearwater.com/frequently-asked-questions/ search EN13319

no influence on decompression (pressure), only on depth value (something like 0.50m difference at 60 m)

 

[Jax]

I liked the old Predator settings. One can look up the salinity of the various locations and select the correct one.

Water density varies by type. The weight of salts dissolved in salt water make it heavier than fresh water. If two dive computers are using different densities of water, then their displayed depths will differ.

The water density is adjustable on the Predator. In the Advanced Config 1 menu, the Salinity setting can be set from 1000 kg/m³ to 1040kg/m³. A cubic meter of pure water has a mass of 1000kg. So what we are setting is the mass of salts dissolved in the water.

Some guidelines:

Fresh Water = 1000kg/m³
EN13319 = 1020 kg/m³
Salt Water = 1025 to 1035 kg/m³

The EN13319 (European CE standard for dive computers) value is between fresh and salt and is the Predator default value. The EN13319 value corresponds to a 10m increase in depth for pressure increase of 1 bar.

 

[tbone1004]

do you really need your depth that accurate in the ocean? The pressure sensors and deco values don't change, it's just the accuracy of the depth gauge. If you're using it as a bottom timer it might be useful, but if you're following the computers deco schedule it doesn't matter

 

[DJ457]

do you really need your depth that accurate in the ocean? The pressure sensors and deco values don't change, it's just the accuracy of the depth gauge. If you're using it as a bottom timer it might be useful, but if you're following the computers deco schedule it doesn't matter

TBONE, in which setting is the depth gauge more accurate?

 

[JohnnyC]

TBONE, in which setting is the depth gauge more accurate?

Whichever setting matches most closely to the salinity level of the water you're diving.

Personally, my Predators are either set at 1000 for freshwater, or the EN standard.

 

[tbone1004]

depends, if you're in salt water, salt water is more accurate, if you're in fresh than fresh. EN13319 equates 10m to 1 bar, so it's a balance between the two assuming a salinity of 1020kg/m3. Fresh is technically 1000kg/m3, and salt is a nominal 1030kg/m3, but varies from 1025-1035. Most of my diving is done in caves, so it lives in freshwater mode, but when I go in the salty stuff I switch it to salt.

All this is doing is calibrating the depth output on the screen, all of the decompression is done based on the actual pressure so it isn't converted from whatever unit it uses to feet or meters

 

[RonR]

TBONE, in which setting is the depth gauge more accurate?

It depends on where you are diving. If a computer is calibrated to match the salinity (or lack thereof) of your environment. the depth reading will be more accurate- in the tape measure sense. What TBONE is pointing out is that, since decompression is calculated only from pressure, this makes zero difference for decompression calculations inside the computer. Depending on the salinity of the ocean (it varies from place to place) at 100’ depth in sea water your body will see about the same pressure as 103’ in fresh water.


Some research or commercial divers do need to be as accurate as possible about depth measurements, but for most of us it just doesn’t matter. All we need to be accurate about is pressure.

-Ron

 

[DJ457]

Thanks guys. Appreciate the info.
I ocean dive with it set on salt. What's the reason that people would do ocean diving with it set on EN13319?

 

[tbone1004]

so they don't have to change it if they regularly dive salt and fresh water