computer redundancy

[SkimFisher]

I wear an Aeris Epic and a Nitek Plus. Different Algorithms, but I never see a big difference with the diving I do.

 

[DaleC]

To expand a bit on the discussion;

If one were looking to buy a second computer specifically for redundancy should they buy one using the same algorhythm or not?

My thoughts are that one should use the same algorhythm to get the most redundant value from the computer.

If you are running two different algorhythms, you cannot tell if either computer is calculating NDL/time remaining correctly as they will naturally give different values.

If you run two computers using the same algorhythm they should give roughly the same values and if they do not you know one is malfunctioning (unless it can be explained some other way).

I think this would give maximum value, otherwise, one is really throwing away the computer part of redundancy and could just as well use a cheaper bottom timer/depth gauge.

 

[UCFKnightDiver]

To expand a bit on the discussion;

If one were looking to buy a second computer specifically for redundancy should they buy one using the same algorhythm or not?

My thoughts are that one should use the same algorhythm to get the most redundant value from the computer.

If you are running two different algorhythms, you cannot tell if either computer is calculating NDL/time remaining correctly as they will naturally give different values.

If you run two computers using the same algorhythm they should give roughly the same values and if they do not you know one is malfunctioning (unless it can be explained some other way).
I think this would give maximum value, otherwise, one is really throwing away the computer part of redundancy and could just as well use a cheaper bottom timer/depth gauge.

But will you know for sure which one is malfunctioning?

 

[super7]

I dive two Stingers. As rox@ucf said, when there's a discrepancy between the two, which should I trust?

Then another thought. If both computers are used under identical conditions, and an unforeseen
software glitch kills both computers at the same time?

Since I couldn't find an answer to both questions, I'm diving one in computer mode, with the other in gauge mode, hoping that the gauge mode might be more robust.

 

[DaleC]

My contention is that if one wants to get the most benefit from redundant computers one should consider using the same algorhythm. If they are giving signifigantly different values then at least you know one is malfunctioning and can adjust your dive accordingly. If you use two computers that spit out different values because they are following different models how will you ever know if either one is malfunctioning. Different values would be expected.

If you dive one computer in gauge mode then it is just a very expensive Bottom timer/depth gauge.

I guess both computers could be affected at the same time, giving identical false readings but that is sort of like planning for multiple failures. It would be much more likely that they would malfunction seperately rather than simultaniously.

It's not a critism of people diving different computers because they have them or setting one into gauge mode, just a thought to stimulate discussion for those setting out to make a future purchase.
Should I buy two computers with the same algorhythm?
Different algorhythms?
One computer, one Bottom timer/depth gauge?

 

[Rhone Man]

Different: a Suunto D9 and a Sherwood Profile.

The Sherwood is 'air only', but it is a very aggressive computer. The Suunto allows multiple gas switches, but is a very conservative computer.

So my rule is I don't surface until both computers say I can surface. Even when I am accelerating deco on rich mixes, I abide by the air profile on the Sherwood.

 

[Rhone Man]

I dive two Stingers. As rox@ucf said, when there's a discrepancy between the two, which should I trust?

Like the old joke goes: a man with a watch always knows the time, but a man with two watches is never sure...

I like two different algorithms because I get a 'second opinion' on something which is basically a very inexact science. Nobody gets a second opinion from the same doctor twice...

 

[Jorgy]

Not clear to me why one would use two different algorithms......

You would have to dive the most conservative one......if not you risk bending it....

Then it is of no use to you for the lock out period.....

As far as not knowing which computer to use if they tell you two different things.....my sense is that is simple to solve......

If you only had one and it "glitched" you would never know.....

With two similar units if there is a difference, then you know to go to your dive buddy and check their computer (or use the computer between your ears) to see (or determine) which of your instruments is working properly....

I dive two computers because our family owns four, so I have access to two for most dives and I don't have a mechanical depth gauge on my rig......

M

 

[UCFKnightDiver]

Not clear to me why one would use two different algorithms......

You would have to dive the most conservative one......if not you risk bending it....

Then it is of no use to you for the lock out period.....

As far as not knowing which computer to use if they tell you two different things.....my sense is that is simple to solve......

If you only had one and it "glitched" you would never know.....

With two similar units if there is a difference, then you know to go to your dive buddy and check their computer (or use the computer between your ears) to see (or determine) which of your instruments is working properly....

I dive two computers because our family owns four, so I have access to two for most dives and I don't have a mechanical depth gauge on my rig......

M

Then why would you need two computers in the first place?

 

[Jorgy]

I don't recall saying you need to dive with two computers.....

I dive two because I have them already......better to use them than have them sit dry on the shelf........

I like the Vyper as I can download it........:cool2:

I prefer the Gekko for night dives because of the glow in the dark face......

So Gekko on the wrist and Vyper on the waist strap as a backup......

Also for dive vacations and live-aboards on Nitrox, you can keep track of total nitrogen and O2 loading even in the event of a single unit failure.......

As far as I see it there is zero downside to using two computers and lots of upside....so why not.......

M