Backup Computer went into Deco

[Lorenzoid]

In one of these threads about backup computers, someone suggested keeping a backup in gauge mode but tracking exposure with a table if doing multiple dives. Not exactly how I would like to spend my surface interval, but I suppose it is an option. If the primary computer fails, and you have to switch to using the one in gauge mode and consulting a table, you might be able to get in another dive that day. Or not.

 

[oldschoolto]

Once you use tables... It's not a big deal to do.. It's not like it's super hard math.. And after doing it for a bit, You start to remember the numbers that let you do what i call "DECO on the fly" ... Meaning your tracking time and depth in your head and know about where you stand as far as being in or out of DECO... And knowing that a stop at 20' and one at 10' will clear you...

JIM....

 

[DevonDiver]

Selectively jumping between computer and table limits is a very short-sighted approach.

Computers track over multiple days... and if doing a period of heavy diving, they Will account for mid-slow tissue saturation rising over multi-day exposures.

I've yet to see a set of tables that effectively tracked inert gas loading over multi-day missions.

Simply switching over to a set of tables; which haven't effectively tracked slow tissue accumulations, is liable to leave you with unaccounted for inert gas loading.

Tracking deco in your head? Well, maybe if your a mathematically gifted autistic savant... but if you're a regular person, it probably only seems 'easy' because you're failing to consider, and account for, a whole bunch of critical factors.

 

[oldschoolto]

Selectively jumping between computer and table limits is a very short-sighted approach.

Computers track over multiple days... and if doing a period of heavy diving, they Will account for mid-slow tissue saturation rising over multi-day exposures.

I've yet to see a set of tables that effectively tracked inert gas loading over multi-day missions.

Simply switching over to a set of tables; which haven't effectively tracked slow tissue accumulations, is liable to leave you with unaccounted for inert gas loading.

Tracking deco in your head? Well, maybe if your a mathematically gifted autistic savant... but if you're a regular person, it probably only seems 'easy' because you're failing to consider, and account for, a whole bunch of critical factors.

Well, All I can tell you is that for years I dove tables ( in my head ) and my wife dove with a VEO1 most of the diving was above 60' in cold freshwater lakes.. Then a few years ago we started diving in Bonaire.. Again me on tables and her with the VEO.. 2 or 3 dives a day for 10 to 12 days and "NEVER EVER" did I put her VEO into DECO... Last year I was talked into getting a computer by the guys on this board, So I bought 2 VEO3's for the wife and I.. To this day I dive with the VEO3 on my left arm and my watch and bottom timer (uwatec) on my right arm and that's the one I use... I do glance at the VEO3 to just double check my brain.. Tables are only hard if you make them hard.. I'd say 90% of diving can be done with knowing a few lines of tables and a line or two on the rep-table... Now, I'm not talking about doing 5 or 6 deep or multi depth dives a day over a week or two... I'm talking about doing 2 or 3 dives a day spread out over a day.. 100' max depth... I did a few dives last month when I was in Bonaire lionfish hunting at 160' on nitrox 25% and I did use the computer for those dives.. I could have done them on tables but I had a lot of Nitrogen in my body from diving over 5 weeks..

I don't think people should not use computers or to try and do what I do... BUT, I really think people should learn tables and know that a little math and knowing your depth and time... What it takes to get safely to the surface.. And know when your computer is full of Bull$hit....

Jim..

 

[DevonDiver]

So... a sample of 1 specific individual, who didn't get bent.

My comment was about 'switching' from computer to tables. It actually sounds like you keep within tables, which have precedence over the computer.

Providing that precedence errs towards the more conservative, there wouldn't be a problem.

 

[Dave Bevan]

I would only ever use a back up to get out of the water safely. I would just can my diving for the day if my primary broke or take do a conservative dive. I am of the opinion that unless you are doing Tech or cave there is absolutely no need for a back up. Its over kill IMO. However each to their own. But then I've never really seen a decent computer break underwater. I also don't dive solo either. And I live two hours from the red sea. I can understand people worrying about it when they go on holiday etc.

I certainly wouldn't run two different computers. Its like trying to please two different people who have different and sometimes conflicting ideas about how you should safely get out of the water.

I am also lucky enough to be able to dive without a computer tracking my tissues and do the calculations on the fly if I should so wish through the training provided by my agency. So I have many options open to me. Like sometimes I run the ratio, sometimes I run with just my perdix in rec mode (when I'm feeling lazy) and sometimes in Tech with a gauge vyper as back up and a plan depending on what type of diving I'm doing for the day.

A good understanding of Deco Proceedures and a conservative approach gives you a lot of flexability.

Happy Diving!

With regards to the OP I think it sounds like the Cressi maybe gave some penalty deco for a missed stop/fast accent or something similar. Or maybe the depth gauge is overreading. Without downloading both profiles its hard to know what really happened.

I'm still waiting for someone to say have three computers and use two to vote one out if its vastly different. Maybe that is too far!!!!

 

[KeithG]

I would only ever use a back up to get out of the water safely. I would just can my diving for the day if my primary broke or take do a conservative dive. I am of the opinion that unless you are doing Tech or cave there is absolutely no need for a back up. Its over kill IMO. However each to their own. But then I've never really seen a decent computer break underwater. I also don't dive solo either. And I live two hours from the red sea. I can understand people worrying about it when they go on holiday etc.

I certainly wouldn't run two different computers. Its like trying to please two different people who have different and sometimes conflicting ideas about how you should safely get out of the water.

I am also lucky enough to be able to dive without a computer tracking my tissues and do the calculations on the fly if I should so wish through the training provided by my agency. So I have many options open to me. Like sometimes I run the ratio, sometimes I run with just my perdix in rec mode (when I'm feeling lazy) and sometimes in Tech with a gauge vyper as back up and a plan depending on what type of diving I'm doing for the day.

A good understanding of Deco Proceedures and a conservative approach gives you a lot of flexability.

Happy Diving!

With regards to the OP I think it sounds like the Cressi maybe gave some penalty deco for a missed stop/fast accent or something similar. Or maybe the depth gauge is overreading. Without downloading both profiles its hard to know what really happened.

I'm still waiting for someone to say have three computers and use two to vote one out if its vastly different. Maybe that is too far!!!!

3 computers? If you have them, use them. i have had one fail underwater. when thinking redundancy, 1 is none, 2 is one and 3 is just enough?

I think the key take away from this thread is that you should have a good handle on your NDL. you should not blindly follow (a broken) dive computer that is asking you to do something that you should know is silly.

 

[boulderjohn]

Tracking deco in your head? Well, maybe if your a mathematically gifted autistic savant... but if you're a regular person, it probably only seems 'easy' because you're failing to consider, and account for, a whole bunch of critical factors.

It may also seem easy because the situations being tracked were particularly easy. I remember the time I realized a number of years ago that in the series of dives I was doing, nothing really mattered except making sure I did not run out of gas. Some dives really are that simple. Some aren't.

Some agencies actually teach you to do the deco in your head, and what is interesting is that they advocate it for dives that aren't anywhere near that simple. I trained for years with such an agency, and it was that training that taught me that once you get away from the really simple dives with the simple depths and bottom times, there is a real danger to diving that way. Two friends of mine got bent on a dive using that methodology. One of them was using a computer in gauge mode instead of a bottom timer, and that enabled them to use the log to see the profile of the dive they actually did and compare it to the dive they thought they did. They found 3 significant discrepancies. They were convinced they had calculated their deco perfectly, and if they had only had bottom timers, they would have continued to think so. The computer's log showed how wrong they were.

 

[Centrals]

I have been diving with two computers for many yrs and the ONLY reason was failure. Happened twice.
There is no logical reason why I would want to run my back up computer in gauge mode + table to supplement my primary computer. A dive computer is actually a bottom timer + multi-functions. Why would I want to disable the multifunction part and use the computer solely as bottom timer only? If I prefer this way I would have bought a bottom timer in the first place and save some money!

Incidentally, the two computers that I am using are different brands with different algorithms. No problem whatsoever.

 

[Centrals]

I'm still waiting for someone to say have three computers and use two to vote one out if its vastly different. Maybe that is too far!!!!

Do you expect all computers give identical info on the same dive?