Backup analog SPG with AI computer ??

[Dxtreme]

Why is there no sense of urgency for people to have a backup SPG ?????

DOnt you need to know about your tank pressure ??


I am planning to get AI Computer (COBRA) and debating if i need backup Analog SPG ???

IS this wise or i am just wasting my money ?

 

[jonnythan]

You should be checking your tank pressure every couple of minutes. So, if you have a computer malfunction, you should know almost exactly your pressure, and you should know that you have enough to get to the surface anyway.

Even if you have a backup depth gauge, timer, and SPG, you probably wouldn't want to be continuing the dive if your computer dies, do you? So for a standard rec dive leave the backup instruments (except maybe a depth gauge) in the dive bag. You should know your dive time so far within a minute, you should know your tank pressure within 100 psi, and you should know your depth within a couple of feet. Computer dies, ascend, and evaluate the proglem during your SI.

I see absolutely no need for a backup SPG for rec diving. And if you're not doing rec diving, chances are you shouldn't be diving an AI computer (not that I'd really know, but that seems to be the consensus).

 

[DiveTub]

If your AI computer looses the connection for some reason or stops, just end the dive , you should have more than enough air in your tank/s if you are following a conservative dive plan.

You dont have the problems of SPG HP hoses blowing apart
seen a few of those in my time and they are a real bummer

You lose the HP hose and SPG reducing drag, and task loading

I throw on a an SPG if doing Deco or deep diving, but dont bother with it on rec Dives.

I have been using the Uwatec AI Computers currentley the Air Z Nitrox, for about 5 years now and have never lost the connection to the transmitter.

 

[Jonathan]

couldn't agree more with the above responses. Just to add to jonnythan's response though it is usually recommended that if you lose your computer (AI or not) then that's your diving done for the day or 24 hours (depending on manufacturers guidlines).

Jonathan

 

[MikeS]

While maybe not a waste of money, your money could be better spent.

What I use as guidelines for recreational diving is as follows. Recreational is defined as being able to safely ascend directly to the surface. This rules out penetration diving or any diving requiring decompression stops.

· Every diver should have their own functional AI computer, computer and SPG, or depth gauge, SPG, and tables at the start of the dive.

· You should dive the more conservative of yours or your buddy’s.

· If any component fails the dive should be ended, using the other set to surface safely.

So, in this context, what does a backup SPG get you if your Cobra dies, you should be ending the dive anyway since you no longer have a depth gauge? To get much value out of redundancy, you need a totally independent AI computer, computer and SPG, or depth gauge, SPG, and tables. This would allow you to continue the dive safely.

Mike

 

[kcanty]

I currently have air Z nitrox and also wear
the suunto mosquito as a watch and while
I dive. I also carry a SPG in my dive kit.

That way if/when my air Z craps out I can
attach the SPG and continue diving with
the mosquito and the SPG.

I of course do not continue the dive on which
the air Z craps out on. Also it's possible for
the computer to become broken/lost on the
surface.

For single dives it's not an issue, but for liveaboards
and vacations it is. I was 9 days into a 14 day vacation
on Roatan and broke my air Z on the surface. ( Don't
ask how please ) I was able to continue the diving
with the mosquito and SPG.

Note that the backup computer is vital for this scheme
to work. You can't just start out with a new computer
as I had been diving 3-4 dives a day and by wearing
the mosquito, it tracked my accumulated nitrogen.
I could have done the same with tables but this way
was preferable, I think.

Kell