Redundancy demands a back up!!

[Heads Up]

All you need is a simple waterproof analogue watch, dive tables, an analogue SPG and a dive plan you stick to. I agree that the chance of a computer malfunction is remote but is isn't zero and if you are already on a dive and your computer goes west, you have no option but to abandon the dive (as well as any later trips until your computer is fixed)

 

[Sue]

Heads Up

Sometimes it's not a matter of computers malfunction - the situation I've written in thread "Backup of a computer" made me feel happy I have a backup one. Even diving with two computers, I always carry the tables with me.

call me a redundancy fanatic...

Sue

 

[Heads Up]

Meant to post a reply to that thread but hit new thread instead. I agree that 2 computers is an ideal solution, however if you find the cost too prohibitive, you can get by with a $30 waterproof watch and tables.

No such thing as a redundancy fanatic IMHO - I'm the same!!

 

[simonk999]

So I have a question: if my backup computer is a depth gauge and tables (presuming also an SPG), what would I do if my computer fails? Not dive for 24hrs and then use the tables to plan the dive?

 

[neil]

Simon,
That's exactly what you should do. If you were on vacation, you'd wish you had a backup computer!. Also, suppose your computer fails and you gleefully whip out your dive tables only to see that you have gone 20 minutes beyond the no-deco time for your max depth? Got air? Even if you skip the tables' required deco stop, where are you now on the tables? The best backup for a computer is another one. Of course IMHO.
Neil

 

[TexasMike]

Continuing the discussion....

Would it be best to have the same computer (brand/model), or different and then dive by the most conservative of the two?

 

[Iguana Don]

All you need is a good watch with a depth gauge (Citizen Promaster) and a SPG, this will get you back to the surface.

Redundant computers?

Plan your dive and dive your plan.

ID

 

[neil]

Don,
"All you need is a good watch with a depth gauge (Citizen Promaster) and a SPG, this will get you back
to the surface. "

Yeah, I could get back to the surface butt nekkid with a sun dial, but I still wouldn't know what my nitrogen status was.

"Plan your dive and dive your plan. "

Okay, I did. I planned a 90 minute no stop, multi-level dive starting from 60 feet. Now those tables (unless they're some slick custom ones) are a usless piece of plastic.

"(Citizen Promaster)"

For what you paid for that watch you could have bought an inexpensive backup computer.

I think I've made my point, and as usual it is MHO.
Neil

 

[turnerjd]

Originally posted by neil
Okay, I did. I planned a 90 minute no stop, multi-level dive starting from 60 feet. Now those tables (unless they're some slick custom ones) are a usless piece of plastic.

I think I've made my point, and as usual it is MHO.
Neil

Neil,

IMHO, that counts as very poor planning. Yes you are going multi level, but what is your plan? are gou goint to stay deep for 5 mins, 1/2 the dive, untill you have 1000PSI left?.

Generally, If you are doing multi level eg on a wreck you should plan on

Xm for XX minutes to see X
rising to
Ym for YY minutes to see Y
with a final burst to
Zm for ZZ minutes to see Z

If you are doing something like a wall then it is just as easy to plan for example

30m initially, rising to 24 by 10mins
Over the next 20 mins rising to 16m (TDT = 30mins)
Leaving XX minutes at 16m

Both these cases are plannable on the PADI wheel.

Yes, it does take a bit more discipline to do a dive like that, than just to blindly follow a computer, and for dive operators, it means they should give you all the depths necessary to pln your dive properly, but hey, it's only your life on the line.

Just MHO of course

Jon T

 

[neil]

Jon,
Thanks for the reply, I thought this thread was abandoned.
I assure you that I know what a dive plan looks like. The "plan" I gave as an example was a simplistic one to illustrate that in most cases ordinary dive tables are no backup for a dive computer, which of course IS the topic of this thread. You CAN plan with a computer. You can plan on the fly with a computer. I think this is acceptable with typical open water diving, which is what I am talking about.
I fail to see why using a computer is taking your life into your hands any more than using dive tables. I'd rather use a computer than a PADI RDP any day.

The fact is, for this type of diving, you just don't need to plan the dive that closely. If you monitor your computer and air closely and follow basic rules (such as deep-to-shallow), you'll have no problems with a dive profile. The main problem as I see it is that with a puter, the diver themselves must set a level of conservatism for the dive. This can be taught.

The fact is that diver are not getting bent or dying just because of dive computers. The fact is that cavers and tech divers don't use them because they don't DO what they need them to do.

Every dive I go on I "blindly" rely on my regulator. However my eyes are open on the workings and limitations of computers. I've never had one quit, and I carry a backup.

Well, that's my opinion and I know I'm not alone with it. Bottom line, do what works for you in an informed way, and be consistent and safe. Peace.

Neil

Disclaimer and Plea: All my knowledge and opinions are based on open water, no-stop diving. If you reply, please don't mention caves, wrecks, tech, dives deeper than 130 ft., wings, backplates, 7 ft hoses, DIR or GIII. I don't really know jack about that stuff and am tired of hearing about it! Anybody seen any pretty fishes lately?