Why WOULDN'T you use backup gauges with an AI computer?

[gcbryan]

The answer is...

Some people get an AI computer to have all of the info on one screen.
Some people get an AI computer to eliminate an extra hose.
Some people get an AI computer for both reasons.

Those who spent $1,000 to eliminate an extra hose aren't going to keep an analog pressure gauge (and hose).

That's the answer.

 

[Matt S.]

That thread is good.

Clearly... If you don't use backup gauges for your wireless computer... You're gonna die.

On the other hand, if you introduce an extra point of failure into your wireless air-integrated rig by having backup gauges... you're gonna die.

Damn, diving is dangerous!

 

[Thalassamania]

A Gauge that is reading higher than actual pressure is far more dangerous than a computer that fails. It gives a false sense of security. Gauges by their nature are only accurate at a single point on their scale maybe 2 points. So to get to the OP's point is a gauge the best backup to an AI? Maybe it is adequate but part of the convienence of the AI computer is not having the extra hose and weight of a console. In comparison a AI computer such as a Suunto D9 or a Oceanic Atom 2.0 has very little weight and nothing to dangle. To claim a failure is the possibility to leave it behind on a dive is a bit much. You may as well say you jumped in without attaching your regs to the tank. These type of foul ups are supposed to be caught during your buddy check. IMHO a second computer is a better backup although it still may not be perfect.

SPGs are (for a mechanical device) incredibly precise but rather inacurate. We had to test our SPGs yearly with very sophisticated test equipment an found them rarely within even a few hundred lbs anywhere on the scale. But ... the error was almost always an under-reading, and thus on the safe side. We did have several AIs, some hosed and some wireless. They were both quite accurate and quite precise, throuhout their scale. My problem with most AIs, however, lies in the decisions that they make for you, I don't really want a device that has a zero point for my gas supply that is not actually zero (or 150 psi, if they must). I'd love an AI that would let me set bingo air and would ramp to that an then reset itself for my return. Anyway ... I like AIs because they feel more like old time diving before all the hoses.

Why is an analog gauge more likely to read wrong than a computer pressure gauge? Both work on the same mechanical principles. One just produces an electronic readout.

They use very different principles, AIs use strain guages while SPGs use Bordon Tubes.

 

[Matt S.]

They use very different principles, AIs use strain guages while SPGs use Bordon Tubes.

Interesting, I stand corrected.

It IS nice to know that my more expensive instrument may actually be more accurate. Here's hoping I never need to run it down to 200 psi where the manual claims it will stop giving a pressure reading...

 

[=C=]

Because I have a backup AI computer. What do I need a backup depth console for?

This is similar to my case in my rec setup... I Dive hoseless AI and have my old computer in my DS pocket...

I think pople forget its all about matching the gear to the diving! If your boat diving for 30 min at a time on the California coast in 30ft you just dont need a ton of gear. If on the other hand you find yourself at 45M in 6C off the English coast in zero viz then.. well... then you have made some bad life choices.

 

[AussieByron]

I use a Suunto Transmitter on my single cylinder rig. I also dive with both a D9 and Vytec and also a nice glass brass SPG. I like having all my information on one screen (my case two screens) and having a SPG as backup.

Another reason why a backup gauge is good to have is when your diving with Novice divers and you ask them how much air they have left. I pick up my guage and point to it and they can understand what I am asking. If I point to my computer they give me all sorts of strange signs like its lunch time, time for a beer, their watch is a casio etc etc

Regards Mark

 

[The Kraken]

I dive an Oceanic VT-Pro and use a redundant SPG.

If my computer craps out, I can revert to the square or multilevel dive plan that I planned and continue the dive.


But, in answer to your question . . . .

. . . I suppose one wouldn't use a backup SPG because one either doesn't want to or deems it unnecessary.

the K

 

[fnfalman]

Since that I have multiple ports for the high pressure side of the first stage, I think that I will mount an additional hoseless AI computer to go with my original computer. That way I will have redundancy if the first AI computer goes out. But then electronics can fail, so I better use the third HP hole to mount a brass gauge. But then a brass pressure gauge can also fail, so I better use that fourth HP hole to mount a plastic pressure gauge.

And then I better need an extra depth gauge for just in case. I already dive with a watch, so I'm covered there. But I better carry The Wheel just in case both computers die during a dive and I have The Wheel so that I can keep on doing varied profiles dives without losing bottom times.

And then I better carry a pony bottle with a separate reg for just in case my primary bottle fails. But since that pony bottle & regs can fail too, I'd better carry a 3-cuft Spare Air. I also should carry a fixed blade dive knife (just in case sharks attack or fend off terrorist divers) to go with my shears and pocket knife.

On my belt I should be carrying a spare mask for just in case my main mask gets stolen by a harbor seal or get kicked off by a terrorist diver.

Damn, almost forgot. Gotta have a wrist compass to back up the electronic compass on the AI computer. And maybe one of those button compass mounted on a string tied to a D-ring just in case my wrist compass breaks because I accidentally knock it against a boulder because of a massive wave surge.

What else am I missing? Gotta plan for all contingencies.

Hell, I might as hell stay home. Scuba is just too dangerous.

 

[The Kraken]

:lol:

the K

 

[BHB ScubaTroll]

Since that I have multiple ports for the high pressure side of the first stage, I think that I will mount an additional hoseless AI computer to go with my original computer. That way I will have redundancy if the first AI computer goes out. But then electronics can fail, so I better use the third HP hole to mount a brass gauge. But then a brass pressure gauge can also fail, so I better use that fourth HP hole to mount a plastic pressure gauge.

And then I better need an extra depth gauge for just in case. I already dive with a watch, so I'm covered there. But I better carry The Wheel just in case both computers die during a dive and I have The Wheel so that I can keep on doing varied profiles dives without losing bottom times.

And then I better carry a pony bottle with a separate reg for just in case my primary bottle fails. But since that pony bottle & regs can fail too, I'd better carry a 3-cuft Spare Air. I also should carry a fixed blade dive knife (just in case sharks attack or fend off terrorist divers) to go with my shears and pocket knife.

On my belt I should be carrying a spare mask for just in case my main mask gets stolen by a harbor seal or get kicked off by a terrorist diver.

Damn, almost forgot. Gotta have a wrist compass to back up the electronic compass on the AI computer. And maybe one of those button compass mounted on a string tied to a D-ring just in case my wrist compass breaks because I accidentally knock it against a boulder because of a massive wave surge.

What else am I missing? Gotta plan for all contingencies.

Hell, I might as hell stay home. Scuba is just too dangerous.