[Dive computer] buying advice

[Neilwood]

Diving with any computer is a matter of knowing what the algorithm is. All commercially available diving computers are safe - they have to be as the manufacturer wouldn't still be here if divers were getting bent in huge numbers.

Having a conservative computer may not be a bad thing - I am not the fittest diver out there so my Cressi with it's supposedly "conservative" RGBM algorithm is possibly a better fit than a computer running the most liberal DSAT. The fact that my computer might "punish" me for rapid ascents (which may cause issues with bubble formation) etc might actually be no bad thing. I have done a number of 3-4 dive days and never found my DC limiting my dive time.

One thing I would change though (with the benefit of hindsight) would be my choice of screen. Given that I dive primarily in the sometimes none to clear waters of the UK but with occasional night dives on holidays abroad, I would benefit greatly from the easier to read LED type screens instead of the old fashioned LCD types. Had it been on the market I would probably have gone for the Cosmiq or something similar.

 

[toris1968]

As a person that never bought into the buy something you'll never grow out of mentality, I'm here to say I wish I'd of know then what I know now. Figure out where u think you are going to be as a diver first, once a year or 200 times a year, buy a computer that will be useful no matter what. I've had non ai wrist mount, console computers and lately wrist ai computers. Find something that suits your needs now and possibly in the future diving wise and just buy it. Save yourself a lot of heartache, the computer u bought because it was cheap and fit your needs today and no longer does what u thought you wanted it to do later you'll have to sell it for pennies on the dollar vs buy something that is more expensive now and will last 10 years and grow with you as u learn more about diving. Just my .02

 

[stuartv]

Diving with any computer is a matter of knowing what the algorithm is. All commercially available diving computers are safe - they have to be as the manufacturer wouldn't still be here if divers were getting bent in huge numbers.

Having a conservative computer may not be a bad thing - I am not the fittest diver out there so my Cressi with it's supposedly "conservative" RGBM algorithm is possibly a better fit than a computer running the most liberal DSAT.

The DSAT computers will allow you to set a Conservatism Factor, in order to make it more conservative than the default. Choosing a DSAT computer in no way locks you into making aggressive dives. OTOH, if you stick to your training, then buying a conservative computer DOES lock you into making conservative dives.

 

[MXGratefulDiver]

I find all this talk about algorithms a bit too much getting into the weeds, particularly for a novice diver who is going to be more limited by available gas supply than NDLs. I think pretty much any choice of dive computer is going to provide a safe algorithm for recreational diving, and that the whole issue of "conservative" algorithms is essentially overblown. If it's a concern, many computers nowadays come with a setting you can use to change the conservatism of the computer ... although there's a caveat there as well which is that before changing the default conservatism you should have some idea (through experience) of how it's going to affect your physiology ... and what factors might cause you to want to dive a bit more conservatively on any given day.

What a newer diver really should focus on purchasing is a computer that's easy to read, easy to set, and intuitive to understand what the numbers being displayed during the dive are telling you. And for almost all of us, getting one that's EAN compatible is important ... even if you don't currently use nitrox, because at some point if you should decide to you then won't have to purchase a new computer.

Toward that end, I recently purchased a Suunto Zoop Novo for a friend of mine who's an experienced diver, wanted a nitrox computer at a reasonable price point, and wanted to be able to read it easily due to her aging eyesight. Some comments I'd have on that particular model is that it's a good price, it's pretty easy to read and understand (nice display for an LCD screen, with large, bold numbers), fairly intuitive to understand what information is being displayed during a dive. My one knock on the computer is that setting things like time and EAN percentage are not as intuitive as you'd like ... I am pretty experienced with a number of different styles of computer, and I had to resort to a Youtube video to figure out how to set the EAN percentage. There's nothing in the manual that explains it, and pushing buttons that you'd think would get you there doesn't. I found that a frustrating problem, given that it certainly doesn't have to be as complicated as they made it.

The thing you have to understand about computers with LCD displays is that you need to protect the screen, or they become difficult to read as they age and the display gets scratched/clouded from use. Most of the computer choices you will have in your price range use LCD screens, so make sure whatever you purchase comes with a replaceable protector covering the display, so that as it gets used you can simply replace the protective cover in order to be able to restore the computer's readability.

... Bob (Grateful Diver)

 

[stuartv]

I find all this talk about algorithms a bit too much getting into the weeds, particularly for a novice diver who is going to be more limited by available gas supply than NDLs.

...

even if you don't currently use nitrox, because at some point if you should decide to you then won't have to purchase a new computer.

You don't find any irony in suggesting to ignore a factor that could easily be relevant as soon as they finish OW training (i.e. some brand new divers have a low enough SAC right off the bat to be limited by NDL, and many others get there within 6 months), but then to also recommend a purchase factor based on not having to buy a new computer later?

Really, all new computers these days support Nitrox, so that's only something to pay attention to if you're buying an old computer.

But, a brand new diver could easily find themselves limited by NDL very early on in their diving. So, saying to ignore the algorithm, when you have a concern to not want to replace your computer too soon, doesn't seem like good thinking.

People using your line of reasoning seem to be why you see so many computers for sale in the Classifieds that have very few dives on them and are being sold because the person wants something less conservative. OTOH, I have a computer that runs DSAT that is over 2 years old, with 100-something dives on it. I am still quite happy to use it for any recreational diving I do. If I had bought a Zoop instead, I would have replaced it long ago.

 

[MXGratefulDiver]

You don't find any irony in suggesting to ignore a factor that could easily be relevant as soon as they finish OW training (i.e. some brand new divers have a low enough SAC right off the bat to be limited by NDL, and many others get there within 6 months), but then to also recommend a purchase factor based on not having to buy a new computer later?

Really, all new computers these days support Nitrox, so that's only something to pay attention to if you're buying an old computer.

But, a brand new diver could easily find themselves limited by NDL very early on in their diving. So, saying to ignore the algorithm, when you have a concern to not want to replace your computer too soon, doesn't seem like good thinking.

People using your line of reasoning seem to be why you see so many computers for sale in the Classifieds that have very few dives on them and are being sold because the person wants something less conservative. OTOH, I have a computer that runs DSAT that is over 2 years old, with 100-something dives on it. I am still quite happy to use it for any recreational diving I do. If I had bought a Zoop instead, I would have replaced it long ago.

No ... I don't see the irony at all. If you want to increase your bottom time, there are far more important factors to consider than your dive computer algorithm. Focusing on the wrong factors can easily lead to situations where, for example, you find yourself chronically mismanaging your available air supply, which to my concern is a far more important thing to factor into your dive profile than the extra couple minutes of NDL you'll get from using a more "liberal" computer.

I know lots of people who use Suunto computers ... and have been doing so for years ... without concerns over available NDL. Yes, it's good to know what the advantages and drawbacks of a given choice will be ... but it's also important to put them into the perspective of the bigger picture.

... Bob (Grateful Diver)

 

[dmaziuk]

If I had bought a Zoop instead, I would have replaced it long ago.

It is possible, and you may've had it replaced because it was limiting your bottom time (and not for some other reasons), but you don't actually know this. Knowing what you know now, you think you would have.

 

[stuartv]

No ... I don't see the irony at all. If you want to increase your bottom time, there are far more important factors to consider than your dive computer algorithm. )

But, when you are shopping for a computer, and you, one, want to ensure you get maximum bottom time, and, two, want to do your best to ensure you don't want to replace your computer any time soon, then why would you not consider the algorithm as one factor in your purchase?

The irony (to me) is that you would specifically recommend getting one that supports Nitrox for the stated reason of not having to replace the computer soon. But then would counsel to not worry about the algorithm, when it seems pretty clear that a very common reason for replacing a "first" computer is to get one with a less conservative algorithm.

If you are shopping for a computer and you have any concern for avoiding want to replace it soon, then wouldn't you counsel to pay attention to ALL the common reasons why people replace their first computer after a relatively short time or relatively few dives?

Sure, when you're preparing to go diving, there a lot of things to focus on for increasing bottom time - up to the bottom that NDL becomes the consistently limiting factor... But, what you are SHOPPING for a computer, then all the factors that are common reasons to replace one seem like they should be considered. You could still choose a conservative algorithm, but I think that choice should be based on information, not ignorance.

It is possible, and you may've had it replaced because it was limiting your bottom time (and not for some other reasons), but you don't actually know this. Knowing what you know now, you think you would have.

When I bought my first computer, Zoops did not have gauge mode. I KNOW I would have replaced it.

 

[scubadada]

There is very little objective data available on repetitive diving profiles and dive computers. I am not endorsing one algorithm over another, but do advocate that divers be aware of the decompression algorithms prior to their computer purchase. You can make liberal computer more conservative, there's nothing you can do to make a conservative computer more liberal.
http://ads.bonniercorp.com/scuba/PDF/ScubaLab-Computer-Test-September-2014-data.pdf

 

[dmaziuk]

When I bought my first computer, Zoops did not have gauge mode. I KNOW I would have replaced it.

Fair enough. I may have missed that bit when I was shopping for ours, I forget. I do remember considering a zoop back then. I would not have bought one in the first place if I were aware of it, but if I did, that'd be the reason to replace it, yes.