I wish newer computers had a feature that did not assume you were breathing air during your surface interval and allowed you to tell it what you really are breathing, just as you can during the dive.
If working, do you ever need to replace dive computer (Aeris Atmos 1)
- Thread starter georgec02
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What is the alternative other than Nitrox 21?
Corporate Coverup Exposed Divers To Grave Risk According To Lawsuit - DeeperBlue.com
In what appears to be an apparent seven year coverup of a flaw in their Dive computer software, Uwatec is being accused of not notifying the general public
www.deeperblue.com
To those who is not familiar with the case.
Belzelbub
Contributor
Literally, whatever you have a tank of. Breathing a tank of pure O2 at the surface will result in a lower N2 loading than breathing air. I can see the benefit of doing that, but have to think that the number of divers that do that regularly to be quite small.
So, I get why a diver might want the option, but I also get why a manufacturer would not want to include that as a setting. Small handful of divers who do post-dive scrubbing vs. the vast majority of divers who may screw up that setting and find out the hard way, like in the Uwatec case above. Very small market advantage vs. potential for harm. Though big difference is that in the Uwatec case, there was no setting, it was just a flaw in the programming. Flaw that was discovered and swept under the rug.
With that mentality, tri-mix settings shouldn't be available either...
Bezelbub is correct.
Most of my diving is done in a deep (280 feet) sinkhole in New Mexico, and on my last day of a dive trip there, I have to drive home to the Denver area. That involves ascending to altitude on the drive. I breathe oxygen to lower my N2 tissue pressure. NOAA used to have information on how quickly you would move through their tables if you were breathing oxygen after your last dive, but I cannot find anything like that on their website now.
I have known people who breathe from their used tank of nitrox during their surface interval. They know it gives them an advantage for the second dive, but they have no way of knowing how much. As I indicated above, they used to be able to tell that using old NOAA tales, but now they have nothing.
Just to add to what I wrote above, having contacted Shearwater about a similar topic years ago, I believe I know why we don't have this feature.
It would be very easy to add a feature that tracked tissue loading according to breathing gas during a surface interval--it's just an extension of what the computer does during the dive. It would also be easy to track tissue loading to determine when it is safe to ascend to altitude--both NOAA and the US Navy have tables for that purpose using their dive tables as a base. If I am an H diver on the US Navy tables, I can look at their ascent to altitude table to see how long I have to wait until I get to a pressure group that will allow me to ascend to my planned altitude.
The problem is that there is not good research to support this feature, especially for the algorithm they use. If they were to put in a feature that indicated when I had off-gassed enough for such an ascent, depending upon what I was breathing on the surface, they would not have solid research upon which to make the changes. They would be opening themselves to a lawsuit.
When I contacted Shearwater, they told me I should rely on standard flying after diving guidelines.
It would be very easy to add a feature that tracked tissue loading according to breathing gas during a surface interval--it's just an extension of what the computer does during the dive. It would also be easy to track tissue loading to determine when it is safe to ascend to altitude--both NOAA and the US Navy have tables for that purpose using their dive tables as a base. If I am an H diver on the US Navy tables, I can look at their ascent to altitude table to see how long I have to wait until I get to a pressure group that will allow me to ascend to my planned altitude.
The problem is that there is not good research to support this feature, especially for the algorithm they use. If they were to put in a feature that indicated when I had off-gassed enough for such an ascent, depending upon what I was breathing on the surface, they would not have solid research upon which to make the changes. They would be opening themselves to a lawsuit.
When I contacted Shearwater, they told me I should rely on standard flying after diving guidelines.
How much time does the diver spend getting out of the water breathing surface air before switching to their SI gas, and getting in the water for the next dive after switching from their SI gas, and could the inaccuracies here throw the calculations off and result in bends and a class-action lawsuit.
Ascending to altitude in air is worse because delta-pressure in air is not linear and would require entirely different formulae.
"Computers make very fast very accurate misteaks" and when you're selling what plaintiff's lawyers will call "life support equipment" you'd want to leave as little wiggle room for them as you can.
@georgec02 :
Absolutely! My first dive computer was an Oceanic Prodigy. Currently use a Perdix but switched to Shearwater (Petrel 1), many years ago, prior to ever considering venturing into technical diving.
The screen is easier to read than a dot matrix display. Also at night or in dark environments, my eyes can read clear crisp colored letters vs a dim green backlight with black letters/numbers. As an added bonus, the Shearwater units are easier to use, have wireless communication and can use rechargable batteries.
Personally, I was sold when I descended slightly slower than my dive buddy. Three feet above him, I could read his Petrel. Bought one shortly afterwards and sold the Scubapro Luna that I used at the time. There are plenty of reasons outside of decompression algorithms, nitrox, trimix, etc, to buy a "different" dive computer.
O.
Absolutely! My first dive computer was an Oceanic Prodigy. Currently use a Perdix but switched to Shearwater (Petrel 1), many years ago, prior to ever considering venturing into technical diving.
The screen is easier to read than a dot matrix display. Also at night or in dark environments, my eyes can read clear crisp colored letters vs a dim green backlight with black letters/numbers. As an added bonus, the Shearwater units are easier to use, have wireless communication and can use rechargable batteries.
Personally, I was sold when I descended slightly slower than my dive buddy. Three feet above him, I could read his Petrel. Bought one shortly afterwards and sold the Scubapro Luna that I used at the time. There are plenty of reasons outside of decompression algorithms, nitrox, trimix, etc, to buy a "different" dive computer.
O.
SmashMonkey
Registered
We have two 20 y.o. Aeris 300G computers that work just fine in June down to 100'. I just change the battery and O ring before vacation. I recently bought two Oceanic Veo 4.0 computers when our children started diving. They are all made by Pelagic and Veo can switch between DSAT or PZ (Buhlmann 16) so I can opt to have everybody match algos. Or dive with a matching backup computer. On my last trip I compared the NDL times for 1-2 tank shallow fun rec dives and while there are differences between the two algos, it was not huge for those dives.
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Hi @smackboy1
The Airis 300G looks like a perfectly capable PPS computer running DSAT and being nitrox capable.
When you say there were differences in the algorithms, did you mean between DSAT and PZ+, or between 300Gs and Veo 4s both running DSAT?
The former is expected with PZ+ being more conservative than DSAT. The differences for air dives can be seen on pp 56-57 of your Veo 4 owner's manual. The DSAT NDLs have not changed over time.
If there are differences when all computers are running DSAT, it may be that the pressure sensor in one of the 330G may have gone bad and the computer is running in the wrong altitude group. You can easily check all 4 computers by running dive planner and comparing to the NDL tables.
Hope it's the former, Aeris is unsupported. I had the pressure sensor ultimately go out on 2 Oceanic Pro Plus 2s, purchased in 2002. Both were replaced by Oceanic/Huish for $175 each, one in 2017 and one in 2019. My wife and daughter still love those computers.
The Airis 300G looks like a perfectly capable PPS computer running DSAT and being nitrox capable.
When you say there were differences in the algorithms, did you mean between DSAT and PZ+, or between 300Gs and Veo 4s both running DSAT?
The former is expected with PZ+ being more conservative than DSAT. The differences for air dives can be seen on pp 56-57 of your Veo 4 owner's manual. The DSAT NDLs have not changed over time.
If there are differences when all computers are running DSAT, it may be that the pressure sensor in one of the 330G may have gone bad and the computer is running in the wrong altitude group. You can easily check all 4 computers by running dive planner and comparing to the NDL tables.
Hope it's the former, Aeris is unsupported. I had the pressure sensor ultimately go out on 2 Oceanic Pro Plus 2s, purchased in 2002. Both were replaced by Oceanic/Huish for $175 each, one in 2017 and one in 2019. My wife and daughter still love those computers.
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