Dive Computer Algorithms?

[Steve_C]

I have a Zoop and Aeris (oceanic cousin). I have both on every dive. I am almost 70 and usually dive the zoop figuring age is a factor. However, the Aeris gives me valid information. On occassion I have put my Zoop into Deco. Say a buddy has a problem we need to resolve. Or for that matter I need to do something. Better to take our time to resolve things then rush for some imaginary deco line. So far I never have put the Aeris in deco. All computers are cleared by the time I get onto the boat. I look at it as diving conservatively but with the option on a given dive of diving safe but a little less conservative.

I do sometimes ride NDL with the Zoop but not the Aeris.

My Aeris does have one quirk. Battery can get a bit weak before it indicates that. I can tell this has happened when I see the same NDL on the ZOOP and Aeris even though both are supposed to be set at 30%. The quirk is not holding the nitrox setting sometimes on a weak battery during the time before the dive starts.

 

[BackrollO]

Steve, I like your thinking and using my two Oceanics I can do the same which I have been doing while testing. Leave the BUD in the more conservative Pelagic+ and use my intregrated VT4 in the more liberal setting of DSAT reverse of how I have it now. That way I have the a range which I can operate in safely and if I push the limit and send the BUD into DECO, I know I need to ascend a bit sooner. I have read a recent study on Undercurrents that suggested Oceanic owners should run their computers in the Pelagic+ setting and not using DSAT. But with only 300 dives and 4 years experience, I am not anywhere near qualified to decide what algorithm to use?

Thanks to all those who submitted their input, although a few of you were a bit snarky I thought as I have a very valid question that is worthy of discussion. No I don't want to force manufacturers to do something, I just wondered why there is not a standard like the Navy uses or the Rec dive table etc..., just a question from a fairly new DM.

'

 

[Lorenzoid]

Thanks to all those who submitted their input, although a few of you were a bit snarky I thought as I have a very valid question that is worthy of discussion. No I don't want to force manufacturers to do something, I just wondered why there is not a standard like the Navy uses or the Rec dive table etc..., just a question from a fairly new DM.

I didn't mean to sound snarky, but how can there be a "standard" without getting every manufacturer to comply? Keep in mind that the US Navy table, the PADI Recreational Dive Planner table, and still other tables exist--there is no "standard" table, though the US Navy table seems to have provided the starting point for the development of other tables. And that's because the Navy had a head start in gathering data and generating tables on the recreational dive industry. The PADI RDP is the standard within the PADI organization, and other tables may be standard within other organizations.

Here is a recent thread asking about the different tables that exist: http://www.scubaboard.com/forums/advanced-scuba-discussions/504885-different-air-tables.html

 

[DiveNav]

..... I am almost 70 and usually dive .....

That's my goal too

Alberto (aka eDiver)

 

[TSandM]

There's no standard, because nobody knows what the "right" answer is. I remember reading an article years ago by Dr. David Sawatzky, in which he opined, at the end, that the big reduction in DCS came with Haldane's original insight, and that everything else we have done has just been nibbling on the edges. No commercially available computer will produce a significant incidence of DCS, obviously, because the liability is simply too great. Some are known for being much more liberal than others (I remember reading at one point that there had been a number of DCS cases at Bikini Atoll, by people diving Cochrane -- but then again, those weren't really recreational dives.).

I prefer to take the view that there is no bright line on no-decompression time. The closer you come to the limits of any computer, the greater the risk, albeit small. If you are going to push limits, consider incorporating some decompression time into your ascent strategy, and make sure you have the gas (and the skill) to do it.

 

[JohnnyC]

A large enough part of the whole algorithm discussion comes down to how much risk you are willing to take. I can make my Petrel liberal enough that it will bend me like a pretzel guaranteed, even following its advice. I can also make it more conservative than my old Suunto Vyper.

Part of the issue is the search for just how liberal you can get, without actually having an understanding of what decides those factors that dictate conservatism. Many people can justify wanting more bottom time without actually understanding that it comes with greater risk. Since most manufacturers don't actually explain in any real depth, decompression theory, it comes down to marketing and the individual diver educating themselves. Take any look at the typical vacation diver and you'll see that it's the furthest thing from their mind in 99% of that population.

 

[Agility]

In A sense of algorithm - Divernet you can find a comparison of most of the algorithms in the market

 

[stuartv]

If you're pondering algorithms, RonR (who, I believe, works for Atomic Aquatics) has posted a couple of pretty insightful posts recently that you might want to read.

http://www.scubaboard.com/forums/co...-leonardo-too-conservative-4.html#post7342293

http://www.scubaboard.com/forums/co...uter-divemaster-internship-4.html#post7388301


Also, nobody has said it, but I THINK all the recreational computers on the market give NDLs that are equal to or less than the PADI RDP table. Of course, that statement has to be taken with the caveat that the RDP only gives NDLs for square dive profiles, so you cannot compare it directly to the NDLs from a computer used for a dive with a non-square profile.

 

[Steve_C]

RDP only gives NDLs for square dive profiles,

Think I have exactly 4 dives that were a square profile at the planned depth. Those were all drop to the sand, hunt for teeth, depart sand when it is time to go up. Even on those few others that were actually square they were shallower than planned. Such as deck at 100 but spent a lot of time at 90. Almost all dives multi-level with the levels 15 or more feet apart.

 

[BackrollO]

I am much smarter than when I first posed the question on different bottom times. I thank you all for your insight, thread links and such. I will be a better diver as a result. I will continue to compare and add some more safety stop time into my longer and deeper dives if I don't use a graduated ascent. The thread that shows the various dive table comparisons was great as you can see that even in the liberal settings of the Oceanic I am still slightly more conservative than the PADI tables except at 60 and 130'. So this makes me feel better about the Oceanic DSAT algorithm. But I agree that adding some more time to my safety stop is a good thing to do especially if doing multiple dives each day and or spending more time at greater depths which for me is usually not over 90' as deeper means shorter unless you have a specific mission which you need to go deeper. Thanks again...