Computer backed up by analog and dive tables?

[John_B]

I think the best way then would be to dive two computers so that one is the back up to the other. That way both computers a reading same dive profile exactly and backs up the other in case of failure.

That's the way I see it. If you are going to the expense of having two dive computers that you are diving in computer mode, why not dive with both of them? Esp. if you are traveling to some exotic destination or on a liveaboard where you wouldn't want to have to sit out 24 hours while everyone else is doing four or five dives a day. Not much value to have the "backup" on the boat instead of tracking your N2 loading.

The other option is to do all the dives with tables or whatever and have the computer back that up. Not everyone likes that idea, esp. if it means less bottom time compared to a buddy "flying" a computer. YMMV.

(We'll leave the "Is flying your computer to the NDL a good idea?" discussion to another thread, but I see the "Is flying your computer to the NDL, then transitioning to tables a good idea?" discussion has been covered pretty well. )

Now what to do with the analog depth gauge and bottom timer? Having just the SPG at the end of the HP hose sounds very tempting at this point. Any thoughts?

That's what I do. The brass and glass SPGs are pretty durable actually. Tie a bolt snap at the end of the hose near the pressure gauge and clip it off to the d-ring on your left hip, and you are streamlined and free of the danglies. What's not to love?

[String]

Depends on what tables you use.

BSAC 88s you'd just assume tissue code G (the highest) from your last dive and plan from there quite happily. Wouldnt need to sit out at all.

[pasley]

The instruction book for your computer has instructions for what to do in this exact situation. I would recommend following the computer mfg directions...stay out of the water for 24 hours!

Diving a computer will often have you well past what a dive table would allow because a dive table assumes (unless you know how to do the calculations for multi-level diving) you dive a square profile dive. The dive computer computes based on what you actually did so you often do a longer dive than what a dive table would allow because you do not spend the entire dive at the deepest depth of the dive. So the

"If you were not into any DECO you can do as one poster suggested, assume that you were at max NDL for the next depth deeper then you know you were, say 90 feet if you were at 80. Now enter the tables at that level and go for it."

method is not valid and a good way to IMHO get hurt, just like using your dive buddy's computer is a good way to get hurt, 10 feet does make a difference. Since you have no way of knowing your pressure grouping or residual nitrogen after a computer takes a dump, I would stay out for 24 hours and enjoy the ocean view.

Given the aggressive nature of diving on many live aboards with multiple dives on consecutive days, some recommend sitting out a day mid-week as a precaution. So conservative is the order of the day and sit out a day of diving if the computer conks out. If you are not willing to do that, then carry a back-up computer on every dive.

[chilie]

All the points have been covered pretty well- I may just add this mostly useless bit of info, SCUBATOYS.COM has computers that can be used reliaby for a souple hundred bucks. Think of it as an insurance policy against having to sit out any dives due to electronic disagreement. I have the Mares RCBM (?) or something like that, it was 300 dollars and comes with a SPG and small console computer that is water activated and allows a cheap alternative tto tables and redundancy is king in diving.

[RonFrank]

I dive two computers for exactly this reason. I have my Aeris Atoms in my pocket, and dive my Epic. If the Epic fails, my Atmos has been in the water the entire time, and go to that.

However if I DID dive just one computer, and it failed, I would NOT stay out of the water for 24 hours. I'd most likely just do more conservative dives, but continue diving.

This also depends a lot on what type of profiles one is doing. If I were in the Keys, and only doing shallower reefs, I could dive all week without anything but at BT. If doing more advanced profiles, could still likely dive there just because I've done it enough to know where my limits fall.

The idea is to be safe. If one can do that, it really does not matter how that is accomplished. Uncle Pug never used a computer, and did not use conventional tables either.