Am I missing something with the Aqualung 470?

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With DSAT on a first dive at 80 feet with air, my OCi is showing 30 minutes of bottom time. Z+ shows 26 minutes. Suunto shows 28 minutes.
 
@Grateful head

The relative difference in NDL between DSAT and PZ+ remains about the same for repetitive dives as it is for first dives. In general, DSAT has about 10-20% more NDL. PZ+ and Suunto RGBM are very similar on the first dive. Suunto tends to be a bit more conservative on repetitive dives, perhaps particularly with shorter surface intervals.

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@Grateful head

The relative difference in NDL between DSAT and PZ+ remains about the same for repetitive dives as it is for first dives. In general, DSAT has about 10-20% more NDL. PZ+ and Suunto RGBM are very similar on the first dive. Suunto tends to be a bit more conservative on repetitive dives, perhaps particularly with shorter surface intervals.

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Thanks to all for responding. So... according to chart above, at 60’ on air, PZ+ is 9 minutes shorter than DSAT and 18 minutes shorter on 32% nitrox. If that is an accurate assessment, that seems fairly significant. The Oceanic article above states the algorithms adjusting differently for deeper dives, repetitive dives and longer surface intervals. I guess the takeaway is that it would be nice to tailor your dive computer to the type of diving your doing. Would it affect someone like me who mostly is a vacation diver doing two dives a day, with one day at three dives ( afternoon or night dive) over the period of a week? Or is the duel algorithm choice more applicable to a live aboard diver doing 4-5 dives a day over a week or ten day period? I don’t see a live aboard vacation in my near future.
 
@Grateful head

You will always have more NDL time with DSAT than with PZ+. Whether the extra time is useful to you, depends. It depends on whether your dive time is limited by NDL or gas time. If you are diving with a buddy or group, it might depend on the NDL or gas time of somebody else. If the boat you are on has a dive time limit, that would be controlling.

DSAT is generally considered a liberal decompression algorithm. PZ+ is generally considered moderate or middle of the road. There are decompression algorithms that are considerably more conservative, such as Cressi or Mares RGBM.
 
@Grateful head

You will always have more NDL time with DSAT than with PZ+. Whether the extra time is useful to you, depends. It depends on whether your dive time is limited by NDL or gas time. If you are diving with a buddy or group, it might depend on the NDL or gas time of somebody else. If the boat you are on has a dive time limit, that would be controlling.

DSAT is generally considered a liberal decompression algorithm. PZ+ is generally considered moderate or middle of the road. There are decompression algorithms that are considerably more conservative, such as Cressi or Mares RGBM.
Yes that is good to know, want to know real world implications. I’m ok with middle of the road, just don’t want to be the guy who has to go up first when diving with a group and then impede other people’s dive. I realize other factors apply, just don’t want my computer to be the cause of a shorter dive. I never noticed any issue with my very old Suunto.....
 
Yes that is good to know, want to know real world implications. I’m ok with middle of the road, just don’t want to be the guy who has to go up first when diving with a group and then impede other people’s dive. I realize other factors apply, just don’t want my computer to be the cause of a shorter dive. I never noticed any issue with my very old Suunto.....

The differences are non-linear and cumulative: e.g. RGBM is supposed to count "repetitive" dives within 36-hour window whereas by DSAT you're in the clear after 6 hours (but with caveats). IMO what's important is that DSAT is the only algorithm designed, and properly tested, for vacation-type diving; RGBM's extra conservatism is based mostly on theoretical musings many of which came into question in the last decade or so.

DSAT is tuned up for no-stop diving, once you start getting into deco you're better off with Buhlmann's ZH-L. PZ+ is derived from ZH-L and I've never seen any references on exactly how or why, and whether Pelagic ever did any formal testing of it.

4-5 days a week over a week+ period is where DSAT's caveats come in: if you read the original report, they bent their test diver by doing that to the limit, and their recommendation is to take every 3rd day easy, and every 7th day: off. For 2-3 dives a day is shouldn't make any appreciable difference, as you saw with your Suunto.
 

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