Question for Petrel owners - how are you using your computer?

[kensuf]

So are you following the runtimes of the dive plan on the Petrel or following the Petrel's deco schedule entirely? I assume you're using the same deco model for both cut tables and Petrel ?

The tables are cut with multi-deco. I follow the petrel's deco unless I completely disagree with the petrel or the petrel fails. If the petrel fails I can deco out using just my g-shock and the tables.

 

[Dr. Lecter]

He's diving with two highly reliable computers. He's also diving a backup to those, but can that really be expected of everybody realistically?

How much redundancy you need depends on the dives you're doing. 20 minutes of OC deco with a single deco gas after mucking around on a wreck at 120' and I'll be comfortable with just a SW, my watch, a SMB, a reel marked every 10', and either memorizing or scribbling the few stops in my wet notes. 120 minutes of CCR deco with three or four BO gasses after a lengthy scooter dive to 300', and I want plenty of tools for finding my way out of the mess such a dive could become.

Short of an EMP going off nearby, though, I'll agree that analogue depth gauges are probably NO worse, reliability-wise, than basic electronic BTs.

 

[victorzamora]

How much redundancy you need depends on the dives you're doing. 20 minutes of OC deco with a single deco gas after mucking around on a wreck at 120' and I'll be comfortable with just a SW, my watch, a SMB, a reel marked every 10', and either memorizing or scribbling the few stops in my wet notes. 120 minutes of CCR deco with three or four BO gasses after a lengthy scooter dive to 300', and I want plenty of tools for finding my way out of the mess such a dive could become.

Short of an EMP going off nearby, though, I'll agree that analogue depth gauges are probably worse, reliability-wise, than basic electronic BTs.

And I totally get that. What I mean, though, is Agility asked right off the bat what would happen if your two computers failed. Most people preach one computer with a basic bottom timer.....that's no less likely to fail than two computers, especially if you're using two Shearwater products....and especially if you're using both consistently on every dive versus a BT/analog gauge that you only look at upon failure of your primary computer.

I'm not saying two computers is better, but I believe it to be as safe as one computer with a backup. I understand why you'd want two backups. Let me ask you this, would you have a problem with diving three Shearwater computers and ditching your analog gauge (other than cost and bulk)?

 

[Dr. Lecter]

And I totally get that. What I mean, though, is Agility asked right off the bat what would happen if your two computers failed. Most people preach one computer with a basic bottom timer.....that's no less likely to fail than two computers, especially if you're using two Shearwater products....and especially if you're using both consistently on every dive versus a BT/analog gauge that you only look at upon failure of your primary computer.

I'm not saying two computers is better, but I believe it to be as safe as one computer with a backup. I understand why you'd want two backups. Let me ask you this, would you have a problem with diving three Shearwater computers and ditching your analog gauge (other than cost and bulk)?

Do I think there's any difference in reliability between analog depth gauges and computers/electronic BTs? No, with the caveat that most analog gauges I've seen are only marked to 240' and apparently taking them deeper than their marked depth scale isn't good for them over the long haul. That's a concern for me and would be for others I dive with, but it's probably not something everyone has to worry about.

As for diving three SW, the only hesitation I would have is that there's risk in having three identical pieces of technology all running the same code. My wife's Cobalt once freaked out during a dive early one January and started giving some truly insane deco information on a 50' reef dive for no apparent reason...turned out it was caused by a bug in the firmware that was triggered by the date changing over to a new year. Having three Cobalts would have, on that dive, resulted in three useless computers.

 

[Michael Guerrero]

thought I'd revise my answer based on the track the thread is taking.

I dive two dissimilar computers with different deco models as well as the tables. If those went bust, I'd use my SMB marked every 10' and my casio g-schock.

 

[CBK]

thought I'd revise my answer based on the track the thread is taking.

I dive two dissimilar computers with different deco models as well as the tables. If those went bust, I'd use my SMB marked every 10' and my casio g-schock.

What do you mean by using your SMB and marking every 10'? Do you mean that you would deploy your SMB and then proceed to make stops every 10' along with you g-shock?

 

[pensacolaracer]

Indeed I do. If my Planet Ocean decides to quit on top of both my Predator controller and my Petrel, it's probably just my time…no pun intended.

If I could get him to stay with the 2 other divers that are in the water, instead of zipping off on his Genesis, he would have no less than 5 shearwaters, an AP controller and at least 2 bottom timers at his disposal.


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[Dr. Lecter]

If I could get him to stay with the 2 other divers that are in the water, instead of zipping off on his Genesis, he would have no less than 5 shearwaters, an AP controller and at least 2 bottom timers at his disposal.


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If you two would plan for more BT, I wouldn't need to solo this stuff…and now that you've found an imported from Japan catheter for your dry suit, I'm not sure what's holding you back! Let's say 30 minutes between the top of the wreck around 240' and the new pieces I found at 300' next time…please tell me you're not still getting cold on deco in Hawaii in a drysuit ;-)

 

[MXGratefulDiver]

My Petrel is my backup computer ... I use an X1 for my primary. I run both in computer mode, and when doing recreational dives tend to rely on them to tell me when I'm in NDL (I do a lot of multilevel diving). When on deeper, tech dives, I use ratio deco for my ascents and use the computers as a "sanity check" ... if I'm doing the profile correctly they'll both come up clean ...

... Bob (Grateful Diver)

 

[Michael Guerrero]

What do you mean by using your SMB and marking every 10'? Do you mean that you would deploy your SMB and then proceed to make stops every 10' along with you g-shock?

Yes, in accordance with the tables I've cut for the dive. I'm not however making 300' dives.