New diver: Suggested conservatism settings for a Petrel?

C Dub · Aug 12, 2014

I'm a recently certified OW diver, and I bought a Shearwater Petrel.

Anyone have input for which conservatism setting to use? From the manual:

Conservatism - The decompression model conservatism can be set to three fixed levels:
* Low (45/95)
* Med (40/85)
* High (35/75)

I believe the default was medium. Being a new diver, I'm thinking the High Conservatism (short NDL times, longer decompression) setting is a good idea.

Doppler · Aug 12, 2014

Use the high setting and take notes on how you feel after a few dives... if you feel better post dive than before you started, then you CAN crank things back to Medium and continue the "experiement."

The Shearwater Petrel is an excellent choice. It will serve you well.

Dr. Lecter · Aug 12, 2014

While I suspect this won't be an issue with NDL diving, what's more conservative w/r/t gradient factors may be somewhat counterintuitive. While the lower the "HI" factor is, the more conservative it is (longer shallow stop)...whether the longer/deeper deep stops triggered by a lower "LOW" factor are more conservative or more ongassing is something you'll need to figure out based on how you feel. I am not to the point of running 80/95 (though I know some who are) but I'm feeling as good with 50/85 as I did with 30/70 for the same dive (with a LOW of 30, even a HI of 75 did not always leave me feeing awesome).

Just something to think about as you play with the settings.

TracyN · Aug 12, 2014

20/80 serves me well for all deco dives. I rather like the deeper deco stops

DuboisP · Aug 12, 2014

TracyN:
20/80 serves me well for all deco dives. I rather like the deeper deco stops

i like deeper deco stops for an OWD

dreamdive · Aug 12, 2014

As a newly certified OW diver, deco stops should not be of concern for you!
There have been very heated discussions regarding what gradient factor to use in the tech community. I have my own personal justifications for what I dive, but this should not worry you, yet.

Not to long ago, another diver on this forum discovered that by doing "deep" stops on his RECREATIONAL dive put him into deco! I think most tech divers will agree that there is nothing to be gained by doing these quasi-deep stops on a 100 ft dive. Thus, you should not program a lower number at all. Dive a 75/75, 80/80, or even a 50/50 or whatever. Again, since you are NOT doing decompression dives, any settings for GF are completely irrelevant anyway.

I love my Petrels. As far as I am concerned, Shearwater makes the best computer money can buy right now. They are great for tech and recreational purposes and this computer can grow with you should you decide to advance in your diving.

Good luck and safe diving

Claudia Roussos MD
ADD Helium Dive Team

victorzamora · Aug 12, 2014

OP: I'd do what Doppler suggested.

C Dub · Aug 12, 2014

Thanks for all the great replies everyone! Yes, to be clear, I am only running Rec mode, and am not doing any sort of deco diving. I simply used Shearwaters wording from the manual to explain their meaning of the conservatism settings.

OMANDIVER · Aug 12, 2014

Are you using the recreational dive interface?

packrat12 · Aug 12, 2014

When I compared NDLs on my Shearwater in Rec mode to my Oceanic Pro Plus 3, I found that the Shearwater with Low CF was similar (slightly more conservative) to my PP3 with no CF(Default) set on Z+. Z+ is slightly more conservative than the PP3 default model of DSAT with no CF (Default). DSAT is supposed to be equivalent to PADI tables and was very consistent with an much earlier Oceanic computer I have.

Keep in mind that each model behaves differently depending on the type of diving you are doing. I like Doppler’s suggestion for determination also as a general rule. Also keep in mind that all computers are based only on theory and everyone’s physiology is different (even between days and dives) and as a result, may have a more or less tolerance to getting DCS.

I was only looking at NDL limits for specific depths. I do not have enough comparison data for actual Rec dives. I dive the Shearwater both Rec and Tech. I love it in both modes. They have done a great job with the computer.

New diver: Suggested conservatism settings for a Petrel?

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