Atomic Cobalt computer and DCS

[eward4]

After 26 years of diving I just got my first case of the bends last Thursday diving off NC. I'm using an Atomic Cobalt computer and have about 100 dives on it. I was diving the same profile and nitrox mix that we dive 99% of the time. I followed the computer to the second with a 50 ft deep stop and safety stop and still got the bends. I took a spinal cord hit and believe me, I never want that experience again! My question is; has anyone that uses the Cobalt or has heard of someone using the Cobalt been bent? I understand that it's not an exact science and there can be other contributing factors but I always thought that computer was pushing the limits. It gives me about 7 more minutes on the same nitrox mix and depth than my dive buddies that use Suunto Cobras and Mares computers and off gasses a lot faster on the surface interval. I have since set the computer to be as conservative as it could and my bottom time was only decreased by one minute for my target depth. I just want to see if anyone else has had any similar experiences with this computer as I'm considering selling it and getting something else a little more conservative. Thanks for any info!

 

[kensuf]

Computers only measure your bubble loading based on a mathematical model and do not necessarily accurately reflect what is happening in your body. For instance, the majority of them do not add conservatism if you get cold, are dehydrated, or work hard on a dive.

And as you're seeing by comparing the output of one with your buddies, not all computers use the same model.

While I believe they can be a useful tool in your arsenal, they should not be blindly followed and you should adjust your stops/etc based on what you're actually doing during the dive.

 

[mikeycanuk]

You can set your risk level and exertion level on the Cobalt. What were your settings?

 

[LowVizWiz]

Hello eward4!

I'm a proponent of using a computer purely for information and making your decisions based on what you know. For example, You know that your cobalt is more liberal than other computers and you want to dive a little more conservatively, so instead of selling the computer, when you plan your dives reduce the bottom time your computer gives you by 5 minutes or whatever you feel is a better safety margin.

You can also check the table limits (which are conservative) for your planned depth and compare those with your computer and decide that your bottom time will be somewhere in between those two numbers.

In other words, the fact that your computer is more liberal does not mean you have to dive the limit the computer gives you.
I hope that makes sense.

 

[PfcAJ]

Every time you go scuba diving you have a non-zero chance of getting bent.

Its part of the game.

 

[StefinSB]

I'm a proponent of using a computer purely for information and making your decisions based on what you know.

Can you please elaborate on that. The inventor of the model used by your computer knew something and that something is published. You know something, what that is is not clear but if it differs from the model used in your computer wouldn't it better just use your computer in gauge mode and dive based on your knowledge then?

For example, You know that your cobalt is more liberal than other computers

Can you please post a proof for that claim?

 

[Rayallyn]

Most computers have settings on them conservative, to liberal. I set mine to conservative and many other divers who set liberal on their computers will stay at depth longer then I will. I like the conservative setting as I am 64 years of age and do not want to deal with DCS. If I were younger I probably would set it more liberally. Like what what said above about computers and with diving in general you can do everything right and still get DCS.

 

[kensuf]

Can you please post a proof for that claim?

I'm not LowVizWiz but the OP did say this in his very first post on this thread..

It gives me about 7 more minutes on the same nitrox mix and depth than my dive buddies that use Suunto Cobras and Mares computers and off gasses a lot faster on the surface interval. I have since set the computer to be as conservative as it could and my bottom time was only decreased by one minute for my target depth.

 

[industrious95]

A friend of mine who's been diving for 40 + years got bent for the first time after he had over a thousand dives to his credit. No rational reason for "why this time" and he was going nuts asking everyone at a higher skill level then himself, including the sales reps from 3 dive computer companies that come into the shop, "Why me why now?"

Nobody could answer, even after loading his computer's profile into software testers that the reps had. DAN couldn't answer the question. S**T happens.

That's why I get so ticked off when I see a thread where people are looking for loopholes to push their risk higher. (Like the thread a few days ago about flying after diving). Nobody knows why you get bent, we only know the factors that increase the chances of it happening.

Hope you recover fast and get back in the water soon. DSAO.....

 

[Dr. Lecter]

I used a Cobalt for a little over a year and did a substantial number of planned deco dives with it in the 130'-240' range. The RGBM model the Cobalt used was, as expected, more focused on deep stops and seemed to give fairly aggressive total times to surface for deco dives and longer NDLs for rec dives. I've never been seriously bent on any dive, but I did once experience some of what many euphemistically call "niggles" in my shoulders after spending almost 45 minutes at 200' and following the Cobalt's deco schedule. But I don't think that has as much to do with the Cobalt's model as it does with my body not liking deep stop-heavy profiles and too much exertion right after the dive.

A rough comparison was that my Petrel set to VPM-B 0 was the same NDLs as my Cobalt set for its most conservative settings, and a similar disconnect in total deco time for the same dive with the same gas switches was observed. That said, the Cobalt also offers some conservatism tweaks based on age...did you set your birthday right?