Backup for AI wristmount computers?

[FishOutUvH2O]

Actually if you don't dive with both then you won't have the time and depth data to use the tables. So you wouldn't be able to use the backup even in gauge mode.

There are several ways to get Time&Depth to use for the repetitive dive plan, it just depends on which one you feel gives you the most accurate data. Most of the methods will cause you to be far more conservative than you need to be. And the better ones rely on diving with a buddy.

1. A buddy. If you've been close enough to your buddy throughout the dive you can use their computers max. depth and time. Just round down to the next nearest depth that you know you didn't exceed.
2. A dive plan. If you planned your dive and dove your plan, then you had a max. depth planned. If you know you didn't exceed the max. depth in the plan then you can use that and get the time from your buddy.
3. If the dive site has a known max. depth that physically can't be exceeded (like the sea floor), you can use that and your buddy's time.
4. Get into the habit of logging your start time just before you hit the water and then using one of the above methods for max. depth.

None of these are ideal because they tend to make your repetitive dive ultra-conservative, but they are safe and will allow you to dive again that day. This is why remembering to dive both computers is so important.

 

[RAWalker]

There are several ways to get Time&Depth to use for the repetitive dive plan, it just depends on which one you feel gives you the most accurate data. Most of the methods will cause you to be far more conservative than you need to be. And the better ones rely on diving with a buddy.

1. A buddy. If you've been close enough to your buddy throughout the dive you can use their computers max. depth and time. Just round down to the next nearest depth that you know you didn't exceed.
2. A dive plan. If you planned your dive and dove your plan, then you had a max. depth planned. If you know you didn't exceed the max. depth in the plan then you can use that and get the time from your buddy.
3. If the dive site has a known max. depth that physically can't be exceeded (like the sea floor), you can use that and your buddy's time.
4. Get into the habit of logging your start time just before you hit the water and then using one of the above methods for max. depth.

None of these are ideal because they tend to make your repetitive dive ultra-conservative, but they are safe and will allow you to dive again that day. This is why remembering to dive both computers is so important.

All the above violate the rule about 2 divers sharing a single computer and so as a general rule shouldn't be done.
But I would agree that using a great deal of conservative number swapping you could safely switch to tables but it shouldn't be done unless you completely understand what the safety margins are.

 

[FishOutUvH2O]

Actually if you don't dive with both then you won't have the time and depth data to use the tables. So you wouldn't be able to use the backup even in gauge mode.

There are several ways to get Time&Depth to use for the repetitive dive plan, it just depends on which one you feel gives you the most accurate data. Most of the methods will cause you to be far more conservative than you need to be. And the better ones rely on diving with a buddy.

1. A buddy. If you've been close enough to your buddy throughout the dive you can use their computers max. depth and time. Just round down to the next nearest depth that you know you didn't exceed.
2. A dive plan. If you planned your dive and dove your plan, then you had a max. depth planned. If you know you didn't exceed the max. depth in the plan then you can use that and get the time from your buddy.
3. If the dive site has a known max. depth that physically can't be exceeded (like the sea floor), you can use that and your buddy's time.
4. Get into the habit of logging your start time just before you hit the water and then using one of the above methods for max. depth.

None of these are ideal because they tend to make your repetitive dive ultra-conservative, but they are safe and will allow you to dive again that day. This is why remembering to dive both computers is so important.

All the above violate the rule about 2 divers sharing a single computer and so as a general rule shouldn't be done.
But I would agree that using a great deal of conservative number swapping you could safely switch to tables but it shouldn't be done unless you completely understand what the safety margins are.

I couldn't agree more with the rule that 2 divers should not share the same computer. But, that's not what we're talking about here. My list pertains to how to come up with usable bottom time and max. depth numbers to be able to use a table(s) for the next repetitive dive. This is if your computer goes belly-up on you on the first dive and you don't have, or didn't bring, a back-up. I'm definitely not advocating that you use your buddy's computer to keep track of your personal nitrogen loading and/or PO2.

 

[RAWalker]

I couldn't agree more with the rule that 2 divers should not share the same computer. But, that's not what we're talking about here. My list pertains to how to come up with usable bottom time and max. depth numbers to be able to use a table(s) for the next repetitive dive. This is if your computer goes belly-up on you on the first dive and you don't have, or didn't bring, a back-up. I'm definitely not advocating that you use your buddy's computer to keep track of your personal nitrogen loading and/or PO2.

I think that you and I are both on the same page and understand how to approach this problem. I just hope that others with less experience or that don't completely understand don't attempt it casually.

Further if a computer goes belly up on a second dive of the day fudging the numbers becomes an even greater task. Even with 2 computers if 1 were to fail I'd pull the bottom time, Surface interval and depth out of the log of the working computer before the next dive and add my SPG to my regs so I still would have redundancy and could continue if the second computer also failed. This gives me a more accurate set of numbers to plug into the tables even with multiple dives.
As was mentioned earlier this multi layer of backup would be for a dive trip that you really don't want to miss a dive on. For local diving I often wear only 1 computer and wouldn't feel too bad about calling a dive and ending my days diving.