How do you back up your computer?

[NudeDiver]

All I can say is best wishes on your future dives.....as to sarcasm it can be almost as damning as complacency in diving.

Oh no!! Looks like I'm goin' down for sure!!

 

[Teamcasa]

The simple answer is a computer will keep track of your profile and should display your current Nitrogen loading during the dive. On subsequent dives, my computer (Oceanic Pro Plus2) will give me dive limits for the next dive based on the previous dive and surface interval.

The main advantage of using a computer is to safely increase bottom time by taking in the dive profile into account when determining Nitrogen loads. If you try to plug those numbers into a table (square profile), chances are you will not find yourself in deco even after one dive. You have to decide whether to rely on the tables or your computer, the two do not mix well together.

Many divers use a back-up computer or a simple bottom timer for added safety.

In practice, I log my dives with basic stats, but rely on my computer to keep my Nitrogen loading in the green.

 

[diveprof]

I am a two computer convert. With a possible exception of the padi wheel (in a limited way) there is not real way compare the multilevel computer dive with square profile tables. I am not going to let a computer failure keep me out of the water for 24 hours on an expensive dive trip. Nor do I wish to trust my life with one set of electronics. Hence, I dive a wrist and a console mount computer. Electronics and water - yeah a failure point. I prefer to address this with two computers. This said, I never do three minute safety stops (5-8 minutes is average), I do deep stops (1/2 max depth) and I surface only in the "green".

 

[gcbryan]

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.

The literal answer to your question (if I understand it) is the PADI wheel which does account for multi-level dives. I think the real answer is that you just want to have some basis independent from the computer to determine that the computer is giving you good information. Your brain/experience along with memorizing some of the key points of the square profile dive table is how you back up the computer.

You know that with a square profile you can't stay at 100 fsw for longer than 20 minutes and you have approximately 60 minutes at 60 fsw. You also know from using your computer that your total dive time can be much longer than that if much of it is spent much shallower. As long as you pad your dives with extra time at 30 fsw and shallower you can make up for small mistakes as well. So, with more experience diving within a set recreational range and given the above information you have an educated guess as a backup to your computer for those times when you feel that your computer may not be giving you accurate information.

 

[ReefHound]

Any diver worth his fins keeps track of their dive profile....pretty basic stuff!

I suspect you mean with that "third sense" where, much like you could recall in your mind the lefts and rights you made in driving to the store, you could sketch out an approximate profile of your dive. That's quite different from what the OP was talking about with keeping notes about depth and dive time on a slate every few minutes. I don't know anyone who does that and it would significantly detract from the dive.

As for "trusting" the computer or tables, I'm guessing you mean that one should have enough of a sense for the parameters that you could notice something really amiss. Sorta like with the SPG, I "trust" it to be relatively accurate but if I've been diving at 100 feet for 20 minutes and it says I have 2500psi (let's say on an AL80 / 3000psi) then I'm gonna conclude I either grew gills or the gauge is stuck. But I've not heard of computers botching the algorithms while appearing to be working, they fail by dying or locking up. And of course, you have to apply your personal variables. No computer or table can know your actual blood chemistry or physical conditioning or state of mind. Tables are just guidelines.

 

[NudeDiver]

I trust my computer(s) at least as much as I trust my regulator and air supply. To a large degree, my life is in their hands, and if they fail, I'm heading toward the surface.

That said, I also inspect them before using them, give them proper maintenance, an if they seem to be doing anything out of the ordinary, I am suspicious.

 

[SailNaked]

au contraire mon fraire

"Any diver worth his fins keeps track of their dive profile....pretty basic stuff! "



Ok how? how do you keep track of the various depths and times at those depths?

 

[rstofer]

PADI has the Wheel calculator for doing multilevel dives in a manner similar to tables. I have one but haven't gotten with the program yet.

PADI also has the eRDP ML multilevel dive planner in the form of a calculator. I haven't gotten with that program either.

There is a problem with either of these planners: you have to know the profile BEFORE you dive it. Sure, you can back calculate a dive you have already done but what if you overstayed the NDL?

Meanwhile, I have a Nitek Duo dive computer that I will use in conjunction with NAUI or PADI tables. I LIKE diving on the basis of a square profile. So, for the forseeable future, I will be using the computer primarily for depth and bottom time. I will also let the computer deal with the O2 issues of Nitrox but I will be checking against the DSAT tables.

I write the adjusted NDLs for the various depths on my slate. All I have to do is look at my depth gauge and my slate to know when I need to surface.

I don't have enough experience with a dive computer to entirely trust them. I DO have some experience with tables.

Richard

 

[texdiveguy]

"Any diver worth his fins keeps track of their dive profile....pretty basic stuff! "



Ok how? how do you keep track of the various depths and times at those depths?

I am not concerned in particular to anyone specific depth and time with multilevel rec. NDL diving profiles.....I wear a dive computer that tracks this for me.....I do though make mental notes throught the dive as to my current depth and estimated NLD time and over-all dive time....PSI readings. I don't use a slate to manually note all this information--it is not necessary! You should at any point in a dive be able to ascent from that dive without the use of a computer to aid you or you need not be diving.

 

[texdiveguy]

I suspect you mean with that "third sense" where, much like you could recall in your mind the lefts and rights you made in driving to the store, you could sketch out an approximate profile of your dive. That's quite different from what the OP was talking about with keeping notes about depth and dive time on a slate every few minutes. I don't know anyone who does that and it would significantly detract from the dive.

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