computer redundancy

[super7]

Which goes back to my question as to whether you would dive with two of the same first stage regulators. Wouldn't fear of systemic failure transcend all equipment choices?

Well, for first stage regs, I think their simple mechanical construction mitigates the possibility of simultaneous breakdowns, at least compared to computers. (By breakdown I mean out of service and unrepairable on site)

Computers are complex systems with multiple components. They also need software to work out the gas models, and having had enough trouble with PCs have made me testy towards anything requiring software of sorts. I don't mean to say I distrust everything running software, but I won't put too much trust in them either. If the computer dies while diving near the NDL, heading for the surface without any timing device/ depth gauge would definitely make me feel uncomfortable.

 

[Randy43068]

if you use two computers, do you use same manufacturer make/model; same deco algorithm or not.

i am not talking cutting tables and using the (uwatec) bottom timer.

On a typical rec dive I'm of the opinion that you don't need two dive computers. If your computer fails then it's time to end the dive. Signal your dive buddy, shoot a bag or get to the up-line. Anyone should be able to make their ascent to the surface without a dive computer. Your dive buddy should be able to time the safety stop for both of you.

Deco dives are another story all together and you would want to have two timers or computers for that kind of diving.

 

[Jorgy]

There have been many points and perspectives on this thread.....

Everyone is right; there are many options to a single failed computer.......

For me it is simple....a spare computer is a cheap, non-cumbersome, reliable easy item to carry on a dive......any dive.....

Other than the perhaps the initial cost and battery replacement, there is no downside......so why not.......

For me a primary computer failure is a total non-event...other than removing my back-up from its pouch and putting it on my wrist......I can continue my dive, don't have to share with my buddy, don't have to abort, don't have to guess at depth, dive time or safety stop.......and in the case of multi-day dives I keep track of my total N2 and O2 loading.......

Divers carry redundant regulators, lights, cutting tools, masks, multi bladder wings or wing and drysuit, lift devices, dive timers, depth gauges, some use H-valves or doubles, etc......having a back-up seems to be the right way to go for all these items.......so why not a redundant computer?

Just my thoughts......M

 

[AfterDark]

I just bought my 1st computer it makes a nice depth gauge,it's easier to read then the one on my console. If it fails on a dive where I'm actually using it as a dive computer, I'll use the computer I used for decades, it sits right between my shoulders, it has never failed me or caused me to get bent and does not require batteries and cannot be lost or forgotten. The algorithms it uses is a result of years of diving experience and was custom made for me and the diving I do.

 

[WarmWaterDiver]

Me and my diving buddy use the same brand and version of computer and, on diving trips, dive the same profile (no brainer as she is my diving buddy). Therefore, there is my computer redundancy.

Referring to an earlier post on the subject by Capt Frank, I do not recall ever seeing that dive computers were compulsory on charters and live aboards. Therefore what do they do if folks just show up with wheels, dive tables, waterproof watches and analog console?...How would their diving be monitored?

See item #11 of the required equipment list for this operation while they were in business, and they had an excellent safety record for the years they were in operation (about a decade)

Message from the Head Divemaster

 

[WarmWaterDiver]

Well, for first stage regs, I think their simple mechanical construction mitigates the possibility of simultaneous breakdowns, at least compared to computers. (By breakdown I mean out of service and unrepairable on site)

Computers are complex systems with multiple components. They also need software to work out the gas models, and having had enough trouble with PCs have made me testy towards anything requiring software of sorts. I don't mean to say I distrust everything running software, but I won't put too much trust in them either. If the computer dies while diving near the NDL, heading for the surface without any timing device/ depth gauge would definitely make me feel uncomfortable.

Do you own and / or operate an automobile? if so, does it have a carbeurator, points, rotor, and condenser?

If not, did you know all that stuff is now accomplished by electronic fuel injection and a computer, with feedback input to the emissions control sensors?

If you were to rent an identcal brand, model, and model year vehicle, would you expect it to operate significantly differently?

 

[AfterDark]

Do you own and / or operate an automobile? if so, does it have a carbeurator, points, rotor, and condenser?

If not, did you know all that stuff is now accomplished by electronic fuel injection and a computer, with feedback input to the emissions control sensors??

Which for most people put the repair and maintenance of their cars beyond their ability thus raising the cost of operating their car. The components are more expensive and complex. If your car doesn't start your usually stuck. New and improved is not always improved. I still trust my knowledge and experience before my computer. The computer for me is to satisfy the charter ops. I have the cheapest I could find. They are the fuzzy dice hanging from the rearview mirror Only for show.

 

[captain]

I have an Orca Edge and a Oceanic I sometimes dive with both. Both have been with in a minute of each other. I prefer the Edge display but it is heavy and big. I wish someone would put the Edge display in a wrist size computer. I don't like the Oceanic's switching back and forth between modes.

 

[super7]

Do you own and / or operate an automobile? if so, does it have a carbeurator, points, rotor, and condenser?

If not, did you know all that stuff is now accomplished by electronic fuel injection and a computer, with feedback input to the emissions control sensors?

If you were to rent an identcal brand, model, and model year vehicle, would you expect it to operate significantly differently?

Good point. Actually, I prefer cars with cabs and alternators. I went as far as to own a Caterham Super7 (hence my handle name; left my garage for practical reasons after a short while).

Presently, I have two cars at my disposal, and the one I drive daily is a JDM Subaru Impreza (WRX-RA STi Spec C) that's spitting out approximately 350HP and doing 0-100kph in roughly 4secs, thanks to a modified COMPUTER that controls everything from fuel injection to cam phase to spark timing. It also features an ELECTRONICALLY controlled center differential called "DCCD". But then, I do have a twin plate carbon clutch at my foot that will disconnect via pedal operation, and the transmission itself is also manual/mechanical. As for the brakes, they do have boosters, but I have also stopped the car without the vacuum, when the engine stalled while running around corners on a track day. I did try the Nissan GT-R and Lancer Evo X, both with twin clutch automatic transmissions. They were faster around the track, but felt bland compared to cars with manual transmission. So, for me, cars will always have three pedals and a knob.
As for renting an identical vehicle, impossible. But whenever possible, I would rent a car with manual transmission over an automatic transmissioned car with better features.

Maybe you weren't satisfied with my explanation for why I dive two identical computers in different modes? I did have one Stinger die on me while diving once. It went blank and after turning back on, locked up as if I had made a deco stop violation. Quite puzzling since I was diving well within the NDL. This got me wondering whether two might hang simultaneously.

And as for PCs, the Macintosh Plus I was using to write reports back in collage pulled all kinds of pranks on me. System hanging after 20hrs of writing demolishing most of the report, capacitor in the Jasmine HDD's power supply board burning up while writing another report, etc.

If you still aren't satisfied, "I do it because I want to"

 

[WarmWaterDiver]

My satisfaction has nothing to do with this.

"I don't mean to say I distrust everything running software, but I won't put too much trust in them either."

Techonogies for lean burn, emissions controls, etc. have made even the speedometer in your vehicle no longer a device driven by a mechanical linkage. However, I was curious if you chose to use that philosophy in personal vehicle ownership since statistics of automobile accident and injury potential are significantly higher than scuba statistics for accident and injury potential.

Most who woud say 'if a car's coputer is faulty it generally won't start' likely agree with Toyota that only floor mats are at the root cause of unintended acceleration.

Aircraft, even commercial aircraft, employ lots of redundant computers.

So, even if you do everything YOU want to do with the way you handle computers. the way someone else uses computers doen't mean you're "safe" from them - you might get T-boned by a Toyota (or other scenario).

Are y'all not satisfied to see a dive operation that required divers have dive computers and had an excellent safety record for diving two mandatory deco obligation dives per day?