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Underwater Pursuit July 9, 2009

Posted by Chris Sullivan in Equipment.
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My first impressions of diving my new Shearwater Pursuit were about what I expected. This display is a bit harder to read than I’d hoped when the water is dark, but that is mostly down to my deteriorating close-up vision which is a natural result of aging. I think I’m going to have to bite the bullet and get a prescription mask, or at least one of those stick on things that gives some magnification when looking through the bottom of the lens.

I think that Shearwater could develop a bigger font for open circuit divers, as the middle row of the display is unused because it’s dedicated to rebreather oxygen sensors. Doing so would detract from the keep it simple philosophy of the computer, which is one of the keys to reliability, so I’m not going to try to start a user campaign to make it happen.

Some attention is required to make sure the straps are tight enough so the computer doesn’t roll around on the wrist. I have the same issue with the Quantum and it’s actually easier to do on the Pursuit because the straps are made of stretch material, but they should be tightened snugly.

I didn’t get the chance to see the decompression algorithm at work because I was busy with a student on these dives. The log agreed in depth,  time and temperature with my Quantum, after making allowances for the fresh water setting in the Quantum vs. the salt water setting on the Pursuit. The Pursuit is getting support for fresh water one day, I hear, and this will be available as an update for download.

Another thing I noticed was that because I was diving in fairly shallow water a lot of the time and surfaced a bunch of times, the Pursuit logged several dives while the Quantum treated it as one. It’s not a big deal but I prefer the behaviour of the Quantum. Fortunately, I just received this email update from Shearwater via my local dive shop.

We have just completed version 67.

It was originally released as version 62, but there were two bugs that were difficult for us to fix because we couldn’t reproduce them.

Several users were very helpful in providing exact sequences of events that produced the bugs to the extent that we were finally able to reproduce the bugs.

Thank you very much for your efforts.

Please download the release notes. There are a lot of new features added and some refinement of existing features that make the operation even easier.

Some highlights are better calibration, altitude support for calibration and decompression, and support for surfacing during a dive and continuing the log with the same dive number. There is more in the release notes.

This release should also have a feature I know I’m going to appreciate, which is to provide additional deco information based on removing the gradient factors from the algorithm and using the “pure” Bühlmann model. Having this gives a reasonably safe (although less so than with the GF) exit from the water when there’s reason to, like being low on gas, dry suit flood, or just bored. I’m only half-joking with this latter situation as I can see a time when I’d incur a really long deco obligation and may want to push it a little, and this feature would give a lower limit to my deco time. My friends who have Cochrans are out of the water in no time compared to me and my Quantum, but I’m looking for a happy medium because I’m not as young as I used to be.

So that’s all for now. I’ll give a proper report when I go diving in the St. Lawrence again, which will be next weekend, where I’ll definitely be putting the decompression algorithm to the test.

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