Air Integrated Computers -- LONG QUESTION

[large_diver]

Trying to weigh buying the Suunto Vyper vs. the Cobra. My struggle with this decision is based on 2 factors --

Air-Integration -- many experienced divers I know shun AI computers; perhaps just not willing to change with the technology or they are worried about the reliability of the technology. SPGs don't need batteries and RARELY fail. Also, while I'm not a DIR fanatic, I do find some of what they recommend very sensible. The DIR philosophy (and the philosophy of many divers on this site) related to computers is that you should not rely solely on a computer for NDL computations and certainly not for how much "air time" you have left. If a diver follows the "rule of 1/3s" and closely monitors their air consumption, what benefit does an AI compute give you?

Wrist vs. Console -- I can see the benefit of both, depending on the profile of a given dive. Wrist seems to make more sense on deeper boat dives (computer on right wrist, left hand free to operate BC exhaust/inflator). I want to get my buoyancy control to the point where I don't have to use an anchor line to descend/ascend.

Sorry for my rambling question - I would appreciate your thoughts on this topic.

 

[Warhammer]

I went back and forth with this for months before I finally ended up getting a Cobra and I'm glad I got it vs a non-air intergrated model or a wrist mount. As far as the air intergration part failing during a dive, I'd say that's about as likely as an analog SPG doing the same. But if it were to fail, simply end the dive. Now if I were cave diving then I'd want a backup or 2 or 3. But I'm not so I can live without it. I only have 4 dives on my Cobra, but I can tell you I didn't and won't put a whole lot of trust in the air remaining calculation, simply because to many factors can drastically change it. But on every dive I done with it so far, the air remaining went to 0 either right before or during my ascent. But I wasn't simply extending my dive till it read 0, I dove as I always do, by surfacing with 500PSI or so left. And since it hits 0 at 500 to 750PSI, depending on your breathing pattern, I ran out of air time remaining. But it does help you estimate when to begin your ascent, know you have x minutes of air time remaining and it will take you x minutes to make the ascent. It's also very beneficial in estimating how far you can go in an out and back pattern and etc.

Wrist vs hose...More personal choice than anyhing. But I like having it on a hose. I can't lose it or forget it and it's almost as easy to hold it in front of you as it is to hold your wrist in front of you. And eliminating a hose was a non-issue for me because even if I did have a wrist mount air-intergrated computer, I'd still have the analog gauges.

 

[Mario S Caner]

Given the chioces you are trying to make I would go with the Cobra. Air Integration is fabulous. You can if you choose to turn that feature off on the Cobra as well.

Wrist mounted computers can be worn on the B.C. as well, so when you want to stick your arm in a lobster hole, you can. There are also retractable lanyards for the air integrated hoseless computers like the Oceanic Data Trans Plus and the Aladin Air Z o2, both of which are also great choices.

 

[nyc aquanaut]

Hey, I just love the fact that now I have 1 less hose to rig, leaving me with a more streamlined profile, and life is a bit simpler. The Cobra for now can do anything, max depth: 450 ft
altitude:10,000 ft
its great
I got into the sport to progress, now I know that this computer can handle what i wanna do, I can take this thing to 450... And my max is 375, would I need another comp.? Sorry I rambled.....................ha ha

 

[large_diver]

One thing that makes me lean towards the Cobra is the ability to track air usage more precisely.

For those that have the PC download software for the Cobra, what kind of data does it give you regarding air -- starting pressure, ending pressure, usage rate?

 

[Warhammer]

I don't have the interface yet, working on it, but I do use the software which is great even if don't have a suunto computer! And yes, it figures your SAC for you. Here's what gets downloaded from the Cobra:

• depth profile of the dive
• dive time
• preceding surface interval time
• dive #
• Altitude and Personal Adjustment settings
• oxygen % setting and maximum OLF (in Nitrox mode)
• tissue calculation data
• temperature at the beginning of the dive, maximum depth and end of the dive
• dive entry time (year, month, day, & time)
• additional dive info (e.g. SLOW & Madatory Safety Stop violations, Diver Attention Symbol, Bookmark, Surface mark, Decompression Stop Mark, Ceiling Error Mark)
• dive computer serial #
• personal 30 character info
• cylinder pressure at the beginning and the end of the dive (i.e. pressure drop during dive)
• surface air consumption

Using the PC software, you are able to enter setup options such as:

• change the sample rate for profile records/logbook from the default 20 second to 10, 30, or 60 seconds
• input a personal, 30 character field into the Cobra )i.e. your name)
• reset the Dive History maximum depth to zero

Notice the temperatures, alot of other computers don't download the temps. You can also use the dive simulator to experiment with different tanks, dive times, depths, mixes and etc. Great product!

 

[large_diver]

WH -- thanks for the detailed response!

I have a stupid question for you :bonk:

Surface air consumption = amount of air you used from the tank before being submerged? Would this include pumping air into BC during set-up on the boat/dock/shore or does this start only when computer hits the water (and turns on)?

 

[DiverInAk]

You can download the manual and the software from Suunto's web site. I don't own the Cobra (yet), but I've already manually entered my dive log into the dive manager software.

The software will let you run a simulation, and you can choose which computer (favor, eon, cobra, etc..) to use for the sim.

Using the sim, you can change the SAC value. I think it will always show 0 air time at 500 PSI though?

I found a place that will sell me the Cobra/SK7 console for $675.00, which sounds OK.

But download the software http://www.suunto.fi/diving/divemanager.html and play with it a while!

David

 

[Warhammer]

large-diver…. That’s a good question and I’m not sure. You’ve stumped me! I’ll have to research it a little or maybe someone else here can answer it. But if I were a betting man, I’d say, no. Reason why is that the computer doesn’t enter dive mode until after it is submerged to a depth of 4ft or more and it also doesn’t show the air time remaining until then. So I’d say it doesn’t start calculating the SAC and therefore the “air time remaining” until after it’s submerged. But I could be wrong. It may just take the highest and lowest reading and calculate it from there.

This also is a possible answer to another question posted on Rodale’s yesterday about this computer. It was reported that there were discrepancies in tank pressure readings between the Cobra and the software after downloading. The software showed a different reading than the Cobra did for beginning and ending pressures. So if it doesn’t take any air into account prior to entering dive mode, that would explain it. Interesting.

But you are correct that SAC= Surface Air Consumption, but the computer takes depth into consideration when figuring your SAC. So it actualy tells you how long you can stay at a given depth, if you know how to work the numbers. With the Cobra software that is done for you and it will tell you how long you can stay at any given depth, with any given tank, based on the SAC rate, tank, depth and pressure. You can also change the SAC rate to anything you want to see how much of a difference a drop in your SAC would make, as well as a larger tank.

 

[Mario S Caner]

Warhammer is correct, The Cobra will not go into Dive mode until it is subjected to a pressure of 3-4ft (1meter) and therefor will not be able to give you consumption rate and air time remaining numbers.