Dive computer comparisons

[Steve Egner]

Are there any information sources out there that show how computers compare with regard to their levels of conservativism? Anywhere we can look to see computers compared side by side, from most conservative to least?

We're all probably familiar with how our own computers compare to those of our dive buddies. On my last dive trip, the DM told me that my computer was more conservative than the one he was using, and that we should compare NDL's at depth.

We never did the comparison (the Corsair in 100' vis was too distracting).

Have you done your own comparisons, and recorded your observations?

I would find those interesting.

Thanks,

Steve

 

[Red Sea Shadow]

Hi Steve,
I didn't see any formal comparison between dive computers. However, it is known for dive professionals that the Suunto in general is the most conservative.

Dive safe,
Asser

 

[*Floater*]

http://www.underwaterbob.com/dive_computers.htm

 

[Steve Egner]

Red Sea Shadow Thanks for the input. Your comment seems to be supported by the test results indicated in Floater's link.

*Floater* Thanks for the link! Naturally, my computer was not one of those tested. I'll have to dive with a Suunto-wearing buddy to see how my computer fares on the conservativism scale.

Of the computers tested, there were some interesting observations.

Regarding the Suunto Vyper:

Conclusion:

This unit is a good unit for the beginning diver. It supports slow ascents, safety stops are built into its logic and its forward projections appear to be conservative in that they make assumptions closer to “worst case” than “best case”. This unit measure out to be a 60/75 Gradient factor combination with DecoPlanner. Within the recreational limits we tested, it appears to be close to the “Doppler tables” advocated by many agencies. If a diver knows nothing and follows this unit, it will keep him/her out of trouble. If we were counseling a parent about a dive computer for a teenage son, for example, this is the computer we would recommend because of the tendency of teenage boys to “push” limits.

UWATEC Air Nitrox Z:

Conclusion:

This is an aggressive algorithm. We reviewed information on the Uwatec website and found that the “Smart” line of computers from Uwatec offers 6 levels of conservatism adjustment. No such adjustment is available in the line tested. The Smart line in fact, seems to use a more conservative algorithm even in the default setting, because the website claims it would require a 6 minute deco stop after the second dive in our test. The Air Nitrox Z did not at any time on either dive require ANY stops during ascent. This matches to a 92/100 gradient factor combination in DecoPlanner.

This unit is not for basic open water divers. Its lack of safety stop reinforcement and its very aggressive NDL calculations when using the default of the Zero conservatism could allow the casual diver to push limits too far. Having said that, this is a good choice for the advanced recreational diver. The display is wonderful an very easy to get the key data needed to monitor a dive.

Sherwood Wisdom:

Conclusion:

This is a fine advanced recreational computer. It has an aggressive algorithm, measuring at the 90/95 metric on DecoPlanner and thus, should not be dived to limits by those with the oft-quoted “high-risk” profile (i.e. “significantly overweight, in poor fitness, dehydrated, etc.). It is very easy to use, has a great display, with the exception of the ascent rate bar and offers good affirmation of the safety points we stress in Open Water classes (e.g. 3 minute safety stop, plan your gas for your turn around and ascent point, monitor your ascent rate). The very visible surface interval time is a good feature. We did not have the download hardware or software at the time of the test so cannot comment on it.

Our only question about this good product is why it ends up in the “discount” sales channel?

Oceanic Versa Pro:

Conclusion:

Because of interface design issues described above, we would not recommend this unit. In addition to that, it is a very aggressive algorithm (measuring at 96/97 using DecoPlanner), the most aggressive computer tested. Finally, like other Pelagic computers, it does not offer conservatism adjustments so there is no way to “tone down” the default behavior of this implementation. Overall, we cannot recommend the Oceanic.

Aeris AI:

Conclusion:

This is an easy to use computer that is very aggressive in its gas absorption calculations. We cannot recommend this logic for the recreational diver. This might be a fine fit for the very advanced/beginning technical diver, but the combination of easy to use, almost entry level recreational, user interface might seduce a diver into relying completely on its Nitrogen absorption tracking. In comparing it with Decoplanner, this demonstrated logic comes out to be about a 92/100 GF factor mix in DecoPlanner. We know of no technical divers who plan their dives with factors that aggressive. In our measurements, only the standard USN Tables and its sibling computer, the Oceanic described below, are more aggressive. Combine that with the clearly described “Reset” feature and we cannot recommend this computer.

Cochran Commander:

We quickly looked that the tables and found that apparently, this computer at 0% conservatism is built on the USN tables directly..

They re-tested the Cochran, adjusting the conservativism factor to 25%

Conclusion:

This is a very interesting and compelling unit for the very informed diver who wants to be able to tailor his dive monitoring tool (the computer) to his dive plan exactly. The lack of a formal safety stop procedure rules this product out in our minds as an entry level diver tool. However, for the market we feel this is aimed at, it can be very effective. Our opinion of this unit changed sufficiently that one of the test team decided to buy one of the units.

Very interesting stuff.

Steve

 

[*Floater*]

Very interesting stuff.

Steve

I wouldn't pay too much attention to the conclusions, but if your brand of computer is on the graph, then it should give you some idea of how conservative or liberal it is relative to other brands. For example, my understanding is that all Oceanics and Aeris are considered aggresive. In my opinion more aggresive is good because you don't need to dive it aggressively(but you can if you want to without a lockout, and you have more lattitude to dive your own algorithm without it complaining.

For example, I prefer to do deep stops on ascent, reverse profiles and I believe that surface intervals are unnecessary for the way I dive, so if I leave the computer in the computer mode then it's less likely to complain about my diving than the more conservative computers - but I can still get a second opinion.

 

[scubamickey]

Do your own research. I read the write up for the Suunto and it is clear that they don't understand how the SRGBM algorithm works. It is a conservative model, but their "best case/worse case scenario" assumption is not the reason for the results they saw on their computer.

Personally, I have Suunto and I'm happy with the model. However, after having done more research on decompression theory and algorithms, I would now buy the Cochran or even just a bottom timer.

 

[scubatoys]

I'm always floored by this discussion. The folks that say a Pelagic computer is liberal - thus bad. Using this logic it would say that a moisture sensor is the best dive computer. If it gets wet, it tells you to get out.

Diving with a computer is easy. Jump in the water and don't let the big number hit zero. Want to be more conservative?? Don't let the big number hit 5. In fact you can program in audible alarms into the Aeris / Oceanic to do just that.

Saying you should not have a computer that will allow a 60 ft dive for 57 minutes to me is much like saying you should not have a car that has a speedometer that goes past 55. If you don't want to go past that speed... take your foot off the gas.

 

[WarmWaterDiver]

Steve - there's lots of info out there, Here's the best ones I've found in English apart from what's already been posted on this thread. I see nothing wrong with someone wanting to make a more educated decision - maybe because I have nothing to sell and want that for myself as well.

Perhaps these links should be put in a sticky for this forum - Mods, what say you?

http://www.divernet.com/equipment/computers2003/intro.shtml

http://www.divernet.com/equipment/0901comptests.htm

http://www.divernet.com/gear/comps699/main699.htm

http://www.divernet.com/gear/comps995.htm

Don't miss the "related links" section for these articles in RSD

http://www.scubadiving.com/gear/dive_computers/smart,_sleek_and_sexy

http://www.scubadiving.com/gear/dive_computers/crunching_the_numbers

 

[Al Mialkovsky]

Steve I recently sold my Cobra as it was very conservative, too conservative for my tastes. I have been diving the Uwatec Smart Com and I've been very happy with that. Recently I attended a product Knowledge seminar for Uwatec and walked away with their hoseless air intergrated Smart Tec. That one lets me monitor 3 different nitrox levels. I only use two so I got mine with just two transmitters. I've got my deep mix in the main tank and my rich mix in the pony bottle for safety stops.

What I like about the smart computers is that if I program it for a conservative level and decide to dive through it I don't get punished and locked out for 24 hours, it just beeps and says you are now level 1, or whatever. Very nice feature.

 

[Steve Egner]

Thanks all,

Floater:

I wouldn't pay too much attention to the conclusions, but if your brand of computer is on the graph, then it should give you some idea of how conservative or liberal it is relative to other brands. For example, my understanding is that all Oceanics and Aeris are considered aggresive. In my opinion more aggresive is good because you don't need to dive it aggressively(but you can if you want to without a lockout, and you have more lattitude to dive your own algorithm without it complaining.

Hey dude, it was your link! Just kidding. I asked the question mostly to see where my computer landed in the conservativism ratings. As you seem to imply, the exercise of good diving judgements rests with the diver. I appreciate that, as well as your input. Thanks again!

scubamickey:

Do your own research.

Sound advice, I'm trying to do just that. I thought it would be valuable to consider the first-hand experience of other divers, as well as any available technical material.
Thank you.

scubatoys:

Saying you should not have a computer that will allow a 60 ft dive for 57 minutes to me is much like saying you should not have a car that has a speedometer that goes past 55. If you don't want to go past that speed... take your foot off the gas.
Today 02:07 PM

That is absolutely true. Again, my question sought to answer how computers related to one another in a conservative/liberal interpretation of identical dive profiles, not which computers should be considered good or bad, right or wrong. As one who obviously considers the features of many, many, computers, your views are most appreciated. Thank you.

WarmWaterDiver:

Thanks for all the info, that was fun to read. After all that, my personal computer, the Tusa IQ-800 was not compared, only reviewed. Which is fine, I'm looking forward to my own test. Thanks for your input.

Al Mialkovsky:

Steve I recently sold my Cobra as it was very conservative, too conservative for my tastes. I have been diving the Uwatec Smart Com and I've been very happy with that. Recently I attended a product Knowledge seminar for Uwatec and walked away with their hoseless air intergrated Smart Tec. That one lets me monitor 3 different nitrox levels. I only use two so I got mine with just two transmitters. I've got my deep mix in the main tank and my rich mix in the pony bottle for safety stops.

What I like about the smart computers is that if I program it for a conservative level and decide to dive through it I don't get punished and locked out for 24 hours, it just beeps and says you are now level 1, or whatever. Very nice feature.

Al, you clearly value the freedom to exercise good judgement. I intend to use my computer that way too. It looks like you're doing some cool stuff... I'm still on one mix per dive.

My brother in law uses an UWATEC, but not the Smart Com, an air-only model from a few years ago. He's my prime dive buddy, but we haven't had the chance to compare NDL's more than once since I purchased my computer.

I'm also trying to balance my computer's advice with a fitness regimen... I rode last year's RAMROD, and will train for and ride it again in 2007. I'll be sagging for Rachel and a group of her lady friends on the STP next summer... Would Jill be interested? You could ride shotgun or two-wheeled, whichever you'd prefer. I'm looking at something called, "Son of the Death Ride", with 19,000' elevation gain over 132 miles. The aerobic training improves my air consumption rates, and constantly reminds me how good it feels to be under water. Hope to dive with you and Jill again sometime soon.

Thanks for all of your viewpoints,

Steve