Deepblu COSMIQ+ users' experiences please

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I purchased a Cosmiq in March and took it on 16 dives in Key Largo running it alongside a Tusa DC Solar Link. I had no issues and it mostly aligned with the Tusa. Both running the Buhlmann ZHL-16C Decompression algorithm with the Cosmiq being proprietarily modified. I dove twice to the Speigel Grove to about 100 feet without issues, again both computers mostly aligned. Yesterday, while back in the Keys, I dove the Vandenburg twice. The first to 122 feet without issue and mostly aligned. On the second dive which got no deeper than 105 towards the end of the dive and using the Tusa as primary I signaled to my buddy that I hade 4 minutes NDL left. I didn't check the Cosmiq. We did a quick pass through of a compartment and as I was entering noticed the Cosmiq was 1 minute to deco. Before I could ascend the Cosmiq went into deco. The Tusa gave me a warning and recommended ascending but did not go into deco. My buddy was running a Shearwater Teric set 40/80, according to her. She was apparently further from deco than either of my computers. Strangely upon ascending the Cosmiq would show greater allowable bottom time than the Tusa despite going into deco below 100. After the required safety stop, the Cosmiq showed deco at the surface but once I transferred my dives to the phone the deco cleared and there was no lockout. This seemed odd as well. The Cosmiq was set on the progressive setting and so was the Tusa. From reading here, the Cosmiq is extremely conservative especially below 90 feet. That seems correct with my experience. But it is as or more liberal than the Tusa at recreational depths. I know some who believe the Shearwaters can be too liberal or at least can be set too liberal. I might be able to put the Tusa on a medium setting to get them more aligned and just dive more conservative (I see no way to set the Cosmiq more liberal), ditch the Cosmiq and run just the one computer (I like running two if I'm doing deeper dives), or ditch the Cosmiq and get another Tusa or something more aligned with the Tusa. Any thoughts or advice would be appreciated. Is the Cosmiq just way too conservative at deeper depths?
 
Hi @okrunner

Both your Tusa and Deepblu computers run proprietary versions of Buhlmann ZH-L16C, the details of which are not available. Tusa used to run Pelagic Pressure Systems PZ+, I don't know if this is still the case. PZ+ ran roughly similar to a GF high of around 85, but relatively a bit more conservative on repetitive dives. I don't know anything about the Deepblu deco algorithm, but it sounds like it is similar to Tusa.

Your buddy's 40/80 is moderate to slightly conservative. Based on what you say, your computers are a little more conservative at their current settings. Are they set at SF0 and Progressive respectively? When you run 2 computers with different deco algorithms, the more conservative computer will always control your no stop dive unless you are willing to clear any deco obligation to avoid lockout in violation gauge mode. Most computers will clear a short deco obligation during a normal ascent, as you described.

Best of luck with your diving
 
If I remember correctly the cosmic ap allows you to go in and change a few things but it's been awhile since I've looked at it.
As for whether or not it's too conservative, that's up to the individual to decide. Some may like the extra conservatism. Spending a couple more minutes off gassing at 20 feet, as long as you have an adequate gas supply, is not a bad thing if conditions and the boat schedule allow it.
I started decompression diving in 2007 and we were for the most part an older bunch. All nearing or over 50. We ran po2s of 1.3 for the working part of the dive for gas mixes, and I used vpm-B which some don't care for, at a plus 3 conservatism.
Never had an issue with not getting enough time on the bottom.
If you are running two computers they should be running the same algorithm. Not close or similar, but the same. If not, you are essentially diving with a buddy that happens to be you running a more conservative comp.
As a buddy team, doesn't matter who's computer is more conservative and you should not be trying to game one to match the other.
You dive to the most conservative one. Period. That should have been communicated clearly in your ow class.
Being a little more conservative is usually not going to be a problem.
I mentioned the Cosmiq app doesn't allow much more adjustment. Also, had you read the thread, there would be some backstory relevant to what I was discussing. Finally, computers weren't mentioned at all during my OW classes. It's been a minute. I am looking for insight into the Cosmiq algorithm not a lesson on how to be safe.
 
Hi @okrunner

Both your Tusa and Deepblu computers run proprietary versions of Buhlmann ZH-L16C, the details of which are not available. Tusa used to run Pelagic Pressure Systems PZ+, I don't know if this is still the case. PZ+ ran roughly similar to a GF high of around 85, but relatively a bit more conservative on repetitive dives. I don't know anything about the Deepblu deco algorithm, but it sounds like it is similar to Tusa.

Your buddy's 40/80 is moderate to slightly conservative. Based on what you say, your computers are a little more conservative at their current settings. Are they set at SF0 and Progressive respectively? When you run 2 computers with different deco algorithms, the more conservative computer will always control your no stop dive unless you are willing to clear any deco obligation to avoid lockout in violation gauge mode. Most computers will clear a short deco obligation during a normal ascent, as you described.

Best of luck with your diving
Yes, SFO and Progressive respectively. It looks like SF1 on the Tusa may be more conservative and align more with the Cosmiq as far a depths below 100 but still doesn't give me warm fuzzies about what appears to be weird about the Cosmiq algorithm.
 
Yes, SFO and Progressive respectively. It looks like SF1 on the Tusa may be more conservative and align more with the Cosmiq as far a depths below 100 but still doesn't give me warm fuzzies about what appears to be weird about the Cosmiq algorithm.
Many algorithms behave somewhat differently on first rather than repetitive dives and/or at depth. I have posted on some relatively blatant examples for DSAT and Buhlmann.
 
Hello, I can't tell you more than you already know about the Cosmiq algorithm, because it is proprietary and I have not put in the work to reverse engineer it. But, I will say that my experience with it is pretty consistent with yours.

I bought a Cosmiq as my first dive computer, and dived it a few dozen times alongside handful of consistent buddies. Between my main buddies, they were diving Aqualung i300C, Aqualung i450T, Shearwater Perdix, and Suunto Vyper Novo. On every occasion that an NDL was approached, it was my Cosmiq, which I configured in Progressive mode. I never exceed the NDL, but I distinctly recall a dive where we ascended from 95 feet when my Cosmiq reached an NDL of 2 minutes, and my buddy's Aqualung had 15 minutes. This was the second dive of the day, both dives on 32%.

After about 50 dives on the Cosmiq, I picked up a used Shearwater Teric, which I now use as my main dive computer. I still bring the Cosmiq along as a backup, but I leave it topside. I haven't had a failure on my Teric, but I have used the Cosmiq once when I accidentally left the Teric at home, and have lent it out a couple of times.

A friend of mine asked if I would recommend the Cosmiq. I told him no, it's too conservative and too annoying to use, and recommended a Shearwater Peregrine instead -- not having a proprietary, super-conservative algorithm is a big part of that. I stand by that recommendation, because he really likes his Peregrine. It does cost more though. At the price point of the Cosmiq, the Deep6 Excursion has a good reputation here, but I have not used one myself, so cannot speak to direct experience.
 
https://www.shearwater.com/products/perdix-ai/

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