Atomic Cobalt 2: 20m deco after short dive to 45m... super conservative - why? How to change?

[jerbee]

I was on my first dive of the morning to 45 meters (after a 24 hour dive break) and the computer put me in 20+ minutes of deco after hitting 45m after about 15 minutes. The resort owner and I were diving together pretty much at identical depths (he was using a shearwater) and he only had about 5m of deco time. I have the computer set to my age (36) and standard conservativeness (which is the least restrictive setting). Any idea why the computer got so angry at the dive? Or ideas on how I can change some of the settings to make it more in-line with a tech computer’s standard algorithm?

 

[jerbee]

Screenshot from the dive profile

 

[jerbee]

Update: I dove with both the Cobalt and a Galileo today to 50m.. 5m deco for the Galileo and 20+ for the cobalt. It looks like as soon as the cobalt hits deco it mandates at least 20 minutes of deco time... so I’m guessing it’s just the way the algorithm works and there’s nothing that can be done to change it.. is that correct?

There isn’t some way to “jailbreak” the cobalt to allow it to run the Buhlmann algorithm instead of the proprietary one, is there? I love the cobalt, but the way the algo works for deep dives is a huge issue.. any advice would be greatly appreciated.

 

[saxman242]

Does the deco clear on ascent or does it still show a 20 min deco stop when you hit the stop depth?

 

[jerbee]

Yesterday i ascended in the blue per the Cobalt’s instructions and the actual ascent time was identical to the planned deco time (24 minutes I think) and the guy with the Perdix following a nearly identical dive profile as mine was finished 15 minutes before I was including his safety stop… Today I ascended and compared it with the Galileo (which i followed) - the deco time on the cobalt lessened as I went shallower over time, but even after I did my safety stop on the Galileo I still had a 9+ minute deco time violation on the cobalt.

 

[RonR]

Hi, we are the original developers of the Cobalt's user interface, electronics, and firmware, and implemented the RGBM algorithm that it runs. The Cobalt's RGBM implementation is in the middle of the road as far as conservatism is concerned, neither the most conservative or liberal for typical profiles. At 45-50M you are getting into the depths where the Cobalt's algorithm migrates to a fully iterative RGBM calculation. That could result in different sorts of ascent profiles, but shouldn't show dramatic differences in total times. There is no minimum deco time in the Cobalt's algorithm, you could get deco stop totals as short as a minute.

We would really like to look at your profiles to see why you are experiencing such a difference with other computers.

It would also help to know to know what model of Cobalt (1 or 2) you have, and what firmware version is installed.

I will send you a message ("start a conversation" in ScubaBoard speak) with links to software and instructions that will allow for the dive log memory to be sent to us. That's valuable for analysis because it lets us see all of the settings and individual tissue groups.

Just ran a couple of simulations, and if you were at 45M for the entire 15 minutes, you could end up with an 18 minute ascent time. If you went a few meters deeper that could increase due to the differences between the "folded" and "fully iterative" calculation.

To answer your question about Buhlmann, there isn't any way to incorporate another algorithm into the Cobalt- it's just not like a phone or other device that runs an OS. However, we have developed a new Cobalt version that allows the user to switch, on the fly, between the Atomic RGBM implementation and Buhlmann. It's available to Atomic if they choose to go that route.

We have recently started a ScubaBoard Manufacturer's forum under Ocean Concepts to support the Cobalt computers. Ocean Concepts

-Ron