Mass confusion about computers????

[Eric Sedletzky]

Ok, so I’m not a huge computer guy but recently have been paying more attention to computers, algorithms, costs, features, etc. here on SB.
I am looking for something myself, and also keeping an eye out for a new diver buddy of mine that I plan to do some diving with and mentoring.

I bought an Mares Puck a few years ago figuring that it was just a simple basic computer that did everything I needed including nitrox, user battery change, guage mode, auto turn on , etc.
What I didn’t know at the time that I’m reading now is how rediculously conservative they are even to the point of being a nuisance.
This type of infomation is just not available when you buy a new computer,...which algirithms are included for each brand/model, what they are based on, etc. they only tell you how great they are, not what can’t do or their shortcomings.

I thought I had a fairly good grasp on this stuff but apparently not. Is there some sort of resource someone can direct me to with a table or graph that might list the different computers and where they sit on the conservative <> liberal scale?
I read here someone saying that you have to pay about $100 more to get a better algorithm in a moderately priced unit. That’s fine but what are they???
I just want to avoid having to pay $900 + for something that is usable.
Most of the features of something like a Shearwater would be wasted on me since I don’t tech dive.
My buddy is also on a budget so will be looking for value as well.
We’re looking for non integrated wrist computers. We’ll be using G&B SPG’s.
Thanks folks.

 

[JulieM]

My husband and I have the Oceanic Geo 2.0 and love them. We used to have the Suunto Mosquito and the Oceanic gives us double the bottom time. Plus the price is actually reasonable. It is also easy to change the battery yourself.

 

[kelemvor]

If you don't find one, it might be something worth creating.

There are indeed a staggering number of dive computers available for sale. Most shops only sell one or two brands, and of those they usually don't carry every single model. When it comes to dive computers, researching on the internet is the only way to figure it out. Even then it's a lot of work.

I didn't realize Mares was all that conservative. Suunto is legendary for being extremely conservative, even on the most liberal settings. Several tech computers are configurable (Raito/Shearwater/Heinrichs Weikamp), but as you've noticed they're very expensive. There's probably 50-100 computers in between those too.

 

[tbone1004]

realistically just go grab a used Petrel for $400-$500. If you get a Petrel 1 you lose the compass and ability to sync to your iPhone but you weren't getting that in any other computers in that price range anyway

For Sale - Two Shearwater Petrel 1 dive computers

 

[runsongas]

a used oceanic/sherwood computer with the dual algorithm can also be found for under 200 sometimes.

 

[Bob DBF]

Try this, its from 2009 but has a chart of how the algorithms relate to each other.

So you want to buy a new computer?

My Oceanic worked well for me, and when it died, and I found it was obsolete, I picked up a Scubapro, which between the price, and dive time shown by the planner is about the same as the Oceanic. I haven't done enough dives to have it slow me down.


Good Luck

Bob

 

[Umuntu]

I didn't realize Mares was all that conservative. Suunto is legendary for being extremely conservative, even on the most liberal settings.

Mares' DCs are even more conservative than the Suunto's

 

[Umuntu]

Eric

The chart below from Oceanic's website has a comparison of NDLs for a single dive profile. The biggest differences are in the shallows at the end of a deeper dive profile.

The differences get more significant with repetitive dives.

 

[Jonny Wishbone]

Juliem,, so your Oceanic computer lets you stay at 60 feet for over 100 minutes? maybe 110 or 120 minutes???? Forgive me if it was just a typo but I had to play with it. Truth is in the world of rec computers they are all going to be "similar" in allowable time under pressure. They probably wont be dead on but will be within several minutes. My first computer back in the 80's was a Suunto Solution which still works but I have moved on to a color screen. Even it on a first dive will give you 51 minutes of BT at 60'. With the Navy table giving you 60 minutes you would usually head up at 55 minutes to be on the safe side. Knowing that, when my Solution gave me 51 minutes I would head up at about 50 minutes knowing that I used to dive based on the Navy tables. That is only a 4-5 minute difference. At 60 feet with an 80 you are probably low on air 45 to 50 minutes into the dive anyway. So if there is a "rec " computer out there that will give a diver alot (not just a few minutes) more bottom time even if its not double, I would like to know what it is.

 

[KeithG]

Mares' DCs are even more conservative than the Suunto's

There are multiple threads here on SB about aggressive and conservative dive computers and "better" algorithms. Some good info, lots of opinions and likely some bad info mixed in...

One of the issues is secret computer behaviour.

If you look at the chart in the thread that @Bob DBF linked above you will find that the Suunto running RGBM gives 40-48 minutes @ 60 feet (I am unsure why there is a range given?) and the Aladin running Beuhlman gives 51 minutes. Not much of a difference between 48 and 51. And the Mares is listed at 57 minutes - the least conservative of these 3.

There is a common theme in many threads that Suuntos are too conservative. I think if you read between the lines the reality is that Suuntos are not more conservative UNLESS you break one of their secret bad diver rules (like less than a minimum of 60 minute SI, or sawtooth profile or ...) and then the algorithm will start to punish you by reducing NDLs on subsequent dives. The amount of punishment is unclear.

The last computer I purchased was a used Uwatec Aladin on eBay for about $35. I am happy with its algorithm as we normally do not dive deep and the dive ops we use limit our bottom time to 60 or 70 minutes.