Need help choosing a new computer, read this

[tbone1004]

Ok, so I have no relation to DGX other than having bought stuff randomly from them for the better part of the last decade. Standard responses for new computer requests are basically, Petrel is the best, if you are going to spend more than about $400, just buy that. If you want to spend less, the Oceanic Geo 2.0 is good for travel due to being watch size, and at $250 the Hollis DG03 is best bang for buck.

I've never liked the DG03, it is clunky, and generally irritating. Now though, DGX has just put the Zeagle N2ition on their website for $170
https://www.divegearexpress.com/zeagle-n2ition-3-gas-dive-computer

3 gasses, digital compass, user replaceable battery, automatic altitude correction up to 20k ft, 12 compartment monitoring. Still requires a pc download kit, but for the price you can't argue with it. Anyone needing a backup computer, wanting to look into a new computer, needs their first computer, etc, this is basically the only one you should look at unless you have specific requirements and want to spend at minimum 2.5x the money.

Again, if you travel a lot, the Geo 2.0 is probably better because it can just be your normal travel watch. If you want the best of the best, get the Petrel at around $800. If you have AI requirements, I'm abstaining from commenting on that, though the new SeaBear HUDC is what I would recommend for those doing FFM diving.

Hopefully this will help to keep the new topics down at least until the next "big thing" hits the market.

 

[rhwestfall]

from the manual:

7) Algorithm: The N2iTion uses a modified Swiss model, 12 compartment Algorithm by Randy Bohrer.


What is this in common terminology?

 

[tbone1004]

from the manual:

7) Algorithm: The N2iTion uses a modified Swiss model, 12 compartment Algorithm by Randy Bohrer.


What is this in common terminology?

Buhlmann ZHL12

This is the same Seiko computer that Dive Rite, Cressi, and a slew of others had made, this should correlate to a slightly upgraded version of the Dive Rite Trio. Great computer at this price, hell it's a great computer at twice this price.

This is copied from Joel Silverstein from a post on the Cave Diving Forum asking about this phrasing.

Hi Kelly,

The Modified Swiss Algorithm in these computers was created by Randy Bohrer when Seiko got into the dive computer business back in the 1990s. They were/are a major player in air and nitrox dive computers world wide. Many of the Dive Rite units were made by them as were/are many other companies. I contacted Randy today and asked him about the algorithm and here is what he said:

-----------
(from e-mail with Randy Bohrer)

The story of the algorithm development (for the Seiko computers) is fairly simple. There are two Buhlmann algorithms, the ZHL-12 and ZHL-16. Most believe that the -12 or -16 refers to the number of compartments. It actually refers to the number of a, b value (similar to M values) sets that the algorithm has. Both are 16 compartment algorithms. ZHL-16 is the newer algorithm. What is unique about it is that it is possible to calculate the a,b values based on the half-life time. Then you can develop your own algorithm with as many compartments as you like. Of course, selecting half-times that are far beyond what has been done with Haldanean type models (for example something in excess of 800 minutes for nitrogen) would probably not be valid.

So, the question becomes, which algorithm did we use for the Seiko-made units? The answer is ZHL-12 (the older model) with some custom modifications. The reason for that is that the ZHL-16 model produced NDLs that were very different from what dive computer users had come to expect. They were too short. We knew from the wide range of practical experience that the NDLs from popular dive computers were "safe", meaning they produced numbers that did not result in an unacceptable number of cases of DCS (DCI). We found that the older model, without modification, produced both NDLs and decompression stop times that were similar to other units already on the market.

We wanted to build in some extra conservatism in areas where there was traditionally an increased risk of DCS, so we looked at modifying the model. The two primary modifications were to freeze the gas loading calculations during the first 10 minutes of a surface interval, and to add a depth safety factor for repetitive dives. The gas loading "freeze" penalized the diver for short surface intervals, but as the surface interval became 2-3 hours or more, the safety factor had little effect -- just what we wanted. The depth safety factor penalized the diver for repetitive shallow dives, again affecting primarily the NDLs (the bottom time of 40-50 foot dives doesn't usually require decompression stops). The depth safety factor had little effect on deep dives (say 80 feet and deeper), where decompression stops would sometimes be required. The base ZHL-12 model has very good dive test results as well as practical field results, so we didn't feel a need to integrate safety factors that had much effect on decompression dives. The final modification was to select half times that would simplify the gas loading calculations. Because the particular half times we selected were not the same as the base model, we interpolated to determine the a, b values.
==============

An additonal comment he said in another email was:

I am familiar with the prototype version of that unit. It is a great computer and is rather “tried and true”.

==============

To summarize -- the Algorithm in these units is the Buhlmann ZHL-12 with modifications to "penalize" the diver for short surface intervals and to add a depth safety factor for repetitive dives.


Kelly, I also went back into my notes from Hamilton Research Ltd, and see that the oxygen tolerance calcs and CNS recovery incorporated into these units were from the NOAA oxygen tolerance values that Dr. Bill created. Those were also incorporated into all of the Seiko made computers (as well as most every other computer.)

I hope this helps you and others who are interested in what the "modified swiss model" is for these particular dive computers.

Regards,​

Joel Silverstein, VP, COO
Tech Diving Limited

you need to reach me ?
text to 928-230-3680
​

 

[Water Boy76]

You do get a lot for you money with that computer - agreed.

Get a Geo 2.0 as primary and Zeagle as backup. You can customize your geo algorithm to closely match Geo if you want. Problem solved.

 

[Lopez116]

Just curious - why no mention of Suuntos? Too conservative? Pricey?

 

[tbone1004]

Pricing and availability from DRiS, there may be other options but I'm not wasting my time.

Cheapest Suunto is the Zoop at $300 from DRiS. It is a waste of money. It doesn't have gauge mode, doesn't have multi-gas, and at $300 is very expensive. Spend $100 and get the Geo 2.0 with two gas, user selectable algorithm, and watch style, spend half that and get an infinitely better computer mentioned above. Used to be spend $50 less and get the DG03 which was cheaper, had multi gas, normal algorithm, option for air integration etc.

Next is the Vyper at $725. Basically the same as the DG03 except it was almost 3x the price but included a digital compass.

Next is the D4i novo. $825 and that's in the same realm as the Oceanic OCi and the Atom 3.1, but the Atom 3.1 comes with a transmitter for $900. The D4i is $1250 with a transmitter....

All the watches above the D4i *D6i, D9TX, Dx*, etc etc are stupid, unless you're a business guy who also dives all the time, basically only people who would ever have this is a Suunto shop owner.... Same with the Dx/D9 whatever other numbers up there they have that are all well over $1k. One of them does have a compass but Oceanics is cheaper by like $300, but still a $1300 computer. Completely idiotic. Only reason to buy the D6i over the OCi is if you are working for a shop that sells Suunto/Aqualung over AUP, or you really want the Suunto and it is worth spending an extra $300. Doesn't make sense to me, but to each his own.

Eon Steel, continuing with the stupidity, this computer is $1440 WITHOUT the transmitter, $1900 with it. It does nothing more than the Petrel other than AI, does it in a less elegant package with the three buttons on the face, and costs 2x as much before the transmitters. Don't believe the CCR support is out yet, but for $1300 you can get a Petrel that has external PO2 monitoring. Save $150 and get a better CCR backup computer, save $800 and get a better computer without AI capability. It's a no brainer.


Note, none of these justifications mentioned Suunto's algorithm as a reason to not buy them. That is icing on the cake for many divers, but the lack of Suunto has nothing to do with their wonky algorithm, it has everything to do with them being a horrible value for the money when compared to other options on the market. You have three choices, puck style, watch style, brick style. Puck style, the Zeagle is a no brainer at the price it is at. Watch style, the Geo 2.0 has no competition. Brick style the Petrel has no competition. Seabear will be launching a few computers that will be worth looking at where the watch style computers have very nice Petrel style screens, etc, but they will be at a price that is difficult to justify. APD trusts them with their rebreather for the new HUDC, so I trust the computer, but it's not a good value right now. The wired AI computers are difficult to recommend because there are only a few of them out there and they all stink imho. They are too expensive for what they are and if you want/need AI, the wireless ones are a better option right now because the computers are more versatile and that is worth the extra money and slightly lower reliability to me IF and only if you really need it. I don't think anyone actually needs it, so I don't bring them up other than "this computer is good and has the option of a transmitter if you want it"



Edit: Disclaimer: I don't necessarily like AUP products, I avoid buying anything and recommending things for various personal reasons. My dive buddies will tell you that it says a lot that I am recommending Oceanic dive computers in the above thread because it is very rare you see me recommend anything from AUP. The fact is there are no better options out there in when you are comparing against other computers. They make the computers themselves, and they do a damned good job of it. That said, the only real options are the Zeagle and Petrel unless you are a vacation/resort type diver or live in an area where you dive regularly without exposure protection in which case a watch style that you wear as an everyday watch makes the most sense. Geo 2.0 for dive watch you only wear on vacation, OCi if you want to wear it as an everyday watch, Suunto only if you are bound to Aqualung products through a shop etc.

 

[Keith.M]

So how did you find this? I shop often with DGE and had not seen this.

When you go to their top level page for computers, it is not even listed.

https://www.divegearexpress.com/computers

 

[ronscuba]

What is your recommendation and analysis for air integrated hoseless ? Recreational diving only.

You mentioned the Oceanic OCI. Nice looking watch size computer. I researched a little more and discovered elapsed dive time is not displayed on the main screen. You have to press a button to get the 2nd screen to see your dive time. Sounds minor, but depth, NDL time, tank pressure and dive time are things I want to see on the main screen on a AI wireless dive computer.

 

[tursiops]

So how did you find this? I shop often with DGE and had not seen this.

When you go to their top level page for computers, it is not even listed.

https://www.divegearexpress.com/computers

It is in their Bargain Annex, and I'll bet it doesn't last too long!
https://www.divegearexpress.com/zeagle-n2ition-3-gas-dive-computer

---------- Post added May 27th, 2015 at 04:34 PM ----------

I'll say one thing for tbone, he isn't always right but he is never in doubt!

 

[eelnoraa]

Looks like a very good computer to begin with. And at that price, it is a no brainer. The manual seems to be the wrong manual. The computer screen is dot matrix type. The one shown in manual is trandition LCD type, and manual doesn't describe compass mode at all. I also wonder if any of the dive mode shows second in dive time, if it does, and if there is bungee mount for it, this is really hard to beat.