How do you back up your computer?

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SailNaked

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I was logging some dives off my computer and I came across these 2 dives.

#1 53ft for 1:02
#2 1:33 SI then 52ft for 56min.

the computer had no problems with them. If I had been using the tables i would not have done the second dive.

So how do you do it in the real world, obviously there is a huge multilevel benefit in these dives but to be able to use it I would have had to keep a slate of all my actual depths and times. Is there any system people have when diving multilevel to keep up with all the depths and times? I like tables, I want to use them, I do not have 100% faith in my computer.

old school wisdom was that you could not get in trouble under 60 ft with an 80cf tank and at least 1-2 hours SI. obviously not so.
 
I am confused. Where does a multi level dive come into play with the information you have offered? I see two dives with square profiles. Perhaps offer up the rest of the information and things can be evaluated and commneted on.
 
I am confused. Where does a multi level dive come into play with the information you have offered? I see two dives with square profiles. Perhaps offer up the rest of the information and things can be evaluated and commneted on.

I do not need anyones opinion on the dives. they were managed by a computer and are just diver history. However if you put them into a square profile like you say they are way outside the limits.

my question is how do people manage multi-level dives so that they can use the tables to back up their computers. how many points do you keep? every 10 feet? do you have a short hand? do you program your watch to beep every 5 min and you write the depth? what? carry a wheel with you under water? 8X11 slate?

people say you should use the tables to back up the computer how do you do that? and please do not say you plan your dive and dive your plan, dive someplace you have never been and tell me you have calculated the exact depths you will be at and the times, and currents. bah.
 
I don't believe that square tables are a good backup for computers, for exactly the reasons you are citing.

If you have developed the skillset to seamlessly transition from computer to tables (which would involve realtime tracking of your depth/time profile), you likely don't use the computer in the first place.

The most common answer to the dilemma is to select the worst-case "residual pressure group" and go from there.

my question is how do people manage multi-level dives so that they can use the tables to back up their computers. how many points do you keep? every 10 feet? do you have a short hand? do you program your watch to beep every 5 min and you write the depth? what? carry a wheel with you under water? 8X11 slate?

It's much easier to keep a running tally than to write down a bunch of numbers and have to compute something from a bunch of number you wrote down. Like, if I descend to 50 feet for 5 minutes, I'm at 50 for 5. Ascend to 40 and bumble around for 5, now I'm at 45 for 10. Hang around at 30 for 20, now I'm at 35 for 30.

If you keep that running through your head all throughout the dive, you'll have a good idea of where you fall on the table.

Just be aware how... order affects things. 50-40-30 and 30-40-50 may be the same from an average perspective, but if you immediately surface after the third "leg," the decompression will be somewhat different. In this example, it's probably within the margin of error. For others, it may not be. In the following example (two reciprocal dives), the average depth is the same (red dotted line), but the decompression is significantly different.

51746d1226437406-how-do-you-back-up-your-computer-untitled.jpg
 

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Sorry I was way beyond misunderstanding.
 
I use the thingy on my buddies wrist. Between the 2 computers, (different models) we have hardware redundancy and a "backup" or sanity check. The computers won't always agree, but since we always call the dive based on the most conservative computer, we are pretty safe.
 
Yeah, often people will say use tables as a backup but it's not all that practical, especially in the situations where computers are most useful. It's either use the worst case pressure group or write a fair amount of stuff down, neither of which I see as a good alternative.

I carry a backup computer.
 
I had to read the original post about 5 times to figure out what the hell you were asking. When I hear "backup your computer" - I'm thinking of making a copy of its data on some other medium, etc.

I see what you are trying to accomplish - you want to be able to second guess your computer, by using dive tables. I know [/b]why you might want to do this too. But your question is how to do it. I don't have an answer for you either. My inclination is to use instinct and intuition. For example, mine tells me that if I do a 30m dive for 60 minutes, that I probably should not have a 30 minute surface interval before my next dive - no matter what my computer tells me is OK. What about 60 minutes? Probably wouldn't do that either. 90? I dunno, for that one, I'd probably use a table to get a rough idea of what it said, before making a decision.

Overall, I think your idea of using the tables to "backup" the computer is probably not too realistic. You're probably better off getting a second computer, by a different manufacturer, and then make your dives off the most conservative one. Check both of them during your SI each time, and dive accordingly.

Personally, I think I am most likely to make a mistake using the tables, esp. in the way you describe, than the computer is likely to make a mistake using its algorithm - which has been no doubt checked over and over again for errors.
 
I do not need anyones opinion on the dives. they were managed by a computer and are just diver history. However if you put them into a square profile like you say they are way outside the limits.

But they weren't a square profile, which makes the comparison invalid and does not allow you to make any valid conclusions.

Terry
 
Since when are any of us to hold 100% confidence in dive computers or tables?
 
https://www.shearwater.com/products/teric/

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