Question about dive computers

[scubadada]

...Algorithm: this is probably the most contentious area. Every computer is made with at least one (some have 2 that can be switched). Some are quite aggressive (will give longish NDL while getting you out of the water fairly quickly) whereas others are more conservative (will give a larger margin of safety). All computers will allow a range of conservatism to allow you to tailor it depending on fitness etc. Read up on the algorithm(s) for the computer you are looking at before you buy it...

Good advice. Below is a relatively complete listing of available computer brands and the decompression algorithms they run. I have categorized each as conservative, moderate, or liberal. Feel free to disagree with my categories, mainly based on 1st dive NDLs and ScubaLab hyperbaric unit repetitive dive simulations. The emphasis here is no stop diving. The availability of hoseless air integration is designated.

Dive computer brands and decompression algorithms

Aqua Lung manufactured by OEM Pelagic Pressure Systems owned by Aqua Lung, runs PZ+ a Buhlmann variant, moderate, HAI

Atomic runs Atomic RGBM, liberal

Cressi runs Cressi RGBM, conservative

Deepblu runs a Buhlmann variant, conservative

Divecomputer.eu/ Deep 6 Buhlmann ZH-L16C with GF, variable from conservative to liberal

Divesoft runs Buhlmann ZH-L16C with custom GFs, variable from conservative to liberal

Garmin runs Buhlmann ZH-L16C with preset and custom GFs, variable from conservative to liberal

Genesis manufactured by PPS, runs DSAT, liberal

Heinrichs Weikamp (not available in US) Buhlmann ZH-L16C with GFs, variable from conservative to liberal, HAI

Mares runs Mares RGBM, conservative, HAI

Oceanic manufactured by PPS, runs both DSAT and PZ+, liberal and moderate, HAI

Ratio runs Buhlmann ZH-L16B with preset and/or custom GFs, variable from conservative to liberal, HAI

Scubapro runs Buhlmann ZH-L8 ADT MB or 16 ADT MB, conservative, HAI

Seac (made by Ratio) runs Buhlmann ZH-L16B with preset GFs, variable from conservative to liberal, HAI

Shearwater runs Buhlmann ZH-L16C with preset or custom GFs, variable from conservative to liberal, HAI (PPS)

Sherwood manufactured by PPS, runs DSAT, liberal, HAI

Suunto runs Suunto RGBM, moderate (HelO2, and D9tx run Technical RGBM. DX, Eon Steel and Core run Fused RGBM (Technical/Full) can be liberal), HAI

Tusa manufactured by PPS, runs PZ+, moderate


Notes:

Buhlmann ZH-L16C: 45/95 would generally be considered liberal, 40/85 moderate, 35/75 conservative

HAI: hoseless air integrated option available

PPS: Pelagic Pressure Systems

 

[Belzelbub]

Hello. Just got my ow certification. Looking to buy my first dive computer. Could someone explain what is usually the difference between a beginner dive computer and a mid ranged computer? More specifically, I wanted to know till what point can i use a beginner/budget computer before I need to upgrade. Can I safely use one till the 40m limit? Thanks

Today, a beginner dive computer can be safely used well beyond beginner range. If you start getting into the tech range, and doing deco dives, then you may want to look into a more tech oriented computer, but until then your recreational computer will work just fine.

Years ago, you used to be able to buy an air only computer. Haven't seen one of those in years. May still exist, just haven't seen any. All the computers I see out there are at least Nitrox capable. Comparing an entry level and higher end computer from the same company, you'll find that the same algorithm is most likely used. The higher end computer may offer things like air integration, and a nicer screen, but they'll most likely calculate your dive the same.

There are, however a few things I'd consider when looking at a beginner dive computer. First, is buttons. The more buttons, the better. I won't touch a single button computer. Too hard to navigate. Two buttons is better, three or more is best. Next, take a look at navigating the menus. Some are intuitive, others are not. Third, make sure that batteries are user replaceable and readily available.

 

[Sean Walberg]

I went with a Suunto Zoop Novo. Basic functionality to recreational depths and nitrox compatibility to 40% seemed to be table stakes for dive computers, but I liked that the Zoop Novo has a depth alarm and elapsed dive time, has a user changeable battery, and has 4 buttons. Also has a decent sized screen for the price point. I recently made a video about it:
The way I narrowed down the decision was by looking at the natural stratifications of models -- you have some really simple one button models at one price point, then another ~$100 gets you more buttons (e.g. easier use) and more features like alarms, better screen, logging and downloads. After that you're spending a whack more to get compass and/or air integration, color display, multi gas, etc, so by sticking in that second tier I was able to narrow it down and not spend more than I needed at this stage in my diving.

I figure if I get advanced enough that I need a more awesome computer on my wrist that this will make a good backup.

 

[Thyamine]

I just went through this myself. I basically did what you are doing, asking people their opinions, and Googling reviews. I probably changed my mind three times. Talk to your dive shop about what they recommend, and then look at what other people suggest. What I found earlier this year were the same basic 'beginner' dive computers, so you start to figure out features that you want/need and don't need.

I ended up with a Mares Matrix because it had the features I wanted, but also the display and four buttons were more in line with what I liked using and seeing.

 

[dmaziuk]

More specifically, I wanted to know till what point can i use a beginner/budget computer before I need to upgrade.

I expect most common reasons to upgrade are
- I want a new toy,
- I bought my own regs and want to add a wireless air pressure sensor,
- I am going into decompression training and need a computer designed for decompression diving.

 

[rongoodman]

Another reason often heard is divers looking for a more legible display.

 

[Gareth J]

I expect most common reasons to upgrade are
- I want a new toy,
- I bought my own regs and want to add a wireless air pressure sensor,
- I am going into decompression training and need a computer designed for decompression diving.

Even the Suunto Zoop is full decompression dive computer. The last time I saw a computer that didn't give you decompression information was back in the 90's --- An Aladin Black. It just said STOP and a depth. Crazy.

If a dive computer only gives NDL time then avoid it.

Another reason often heard is divers looking for a more legible display.

Thats a good reason, although I did wait until I broke the controller on my CCR before I upgrade to the new full colour unit.

 

[dmaziuk]

Even the Suunto Zoop is full decompression dive computer.

It's a) not going to give you an optimal decompression profile and b) I strongly suspect even DM5 won't let you plan a deco dive for a Zoop.

"Recreational" computers will get you topside you safe if you overstay your NDL. That is not quite the same thing as computer designed for planned decompression dives.

 

[scubadada]

I expect most common reasons to upgrade are
- I want a new toy,
- I bought my own regs and want to add a wireless air pressure sensor,
- I am going into decompression training and need a computer designed for decompression diving.

And, I bought a computer with a conservative deco algorithm and wish I had one with a more liberal decompression algorithm.

 

[dmaziuk]

I said "most common". Yes, you and Stuart, and who else?