computers and redundancy

[SteveFass]

I was just wondering what redundancies you use for your computer (especially on a tech dive), and whether the backup equipment is with you on the dive or you keep it in the car / boat (keeping it at home doesn't count). If you take it on the dive, where do you wear it?

If your computer is AI, do you have a backup gauge?
A backup computer?
Charts?
A timer?
Depth gauge?
Thermometer? Calendar? (just kidding)

For me, I'm thinking of putting a depth gauge in a pocket, but wondering whether that's being over-cautious.

 

[jonnythan]

I wear a bottom timer on my wrist, and keep a bottom timer in my gear bag on shore or on the boat.

But I don't tech dive. If I do dives with a deco obligation, I will use two bottom timers.

 

[cmalinowski]

I have a backup computer. Since they are both AI, they work as backup guages as well.

 

[miketsp]

I was just wondering what redundancies you use for your computer (especially on a tech dive), and whether the backup equipment is with you on the dive or you keep it in the car / boat (keeping it at home doesn't count). If you take it on the dive, where do you wear it?

If your computer is AI, do you have a backup gauge?
A backup computer?
Charts?
A timer?
Depth gauge?
Thermometer? Calendar? (just kidding)

For me, I'm thinking of putting a depth gauge in a pocket, but wondering whether that's being over-cautious.

Contradictory question, most tech divers don't use a computer as a computer, they use it in gauge mode, then have a second timer and a second depth gauge.

Any deep dive (20m+) I carry tables in my pocket.
If I had AI I would still want a mechanical SPG & alternate depth gauge (watch or mechanical).

 

[DA Aquamaster]

I use an automatic bottom timer attached to a wrist mounted slate. The bottom timer in combination with a software generated dive plan/deco schedule (and contingency schedules) written on the slate are the primary depth/time/deco tools and the computer is the redundant depth/time/deco instrument.

This is preferable in my opinion as it works very well and avoids the temptation for divers to just jump in the water and rely on a computer rather than on proper planning and execution of the dive. If for some unexpected reason the dive is terminated significantly early, the computer will enable you to avoid wasting time on unneccesary deco.

The computer is a hose mounted AI computer and is the primary SPG but I do not use a separate back up SPG per se. However since I dive independent doubles the computer is on the right tank and the left tank has a mechanical SPG. If you are familiar with your SAC rate, are doing proper gas planning and keeping track of gas consumption over the course of a dive, a failure of the electronic SPG in the computer will be quickly noticed and is not going to cause any undue problems as you will have gas remaining for a normal ascent.

 

[The Kraken]

In conjunction with my computer I have my dive watch which gives me time and depth. I also have a stand-alone SPG.

I plan my dives, record the dive on a small slate.

Both my watch and computer are water activated.

Should my computer malfunction I simply revert to the manual dive plan and use my dive watch and SPG. Serves the same effect as entering the water with a bottom timer and SPG.

 

[diverbrian]

Currently, I am using a VR-3 as a primary computer. My back-up is my old VyTec that I put in gauge mode for Tri-Mix. I write basic dive plan info on a slate (with computer generated tables) for tech dives. This information includes my stops for over staying my welcome/ going deeper than planned (Mr. Murphy sometimes strikes in the last two cases)/ or losing my deco gas for some reason.

Either computer will get me safely to the surface and my tables are generated such that the VR-3 will agree to them so long as I stay in my dive plan.

Pressure gauge? I dive manifolded doubles. I have one gauge. If it goes out, the dive is over and I am headed back. Following rule of thirds to my turn pressure, I will know about this well before I have enough gas to have to worry about it. And my planning includes the gas management, so if I stay within my planned time, I am pretty well set for gas. I just use the gauge to verify that I don't have a leak in my tanks or that I am not breathing harder than normal.

 

[ppo2_diver]

For my tech diving, I have a computer on one wrist, a bottom time/depth guage on the other. I also have a copy of my dive plan (with contingencies) on my wrist slate, in my dry suit pocket and taped on the tops of my fins. I suffer from an illness called over-planning.

If I'm just fish tank diving in the Caribbean, I'll just have my computer and my watch has a depth guage built in. The watch is analog.

 

[Atticus]

I carry a Nitec He dive computer and an Uwatec bottom timer on my right wrist. On my left wrist is a slate with my dive profile and a compass. The dive is run by the written profile; the computer is available for bailout and/or sanity checks.

With manifolded doubles I have a single SPG - if it fails the dive is over. That being said, if you choose a good SPG the failure rate is pretty low.

I strongly suggest against using air integrated computers for tech diving - the hose variety are always in the wrong place (under your deco tanks), and the hoseless variety are not very reliable (admittedly this is more due to human failure in these days of better senders, but the failure rate is still pretty high).

 

[Doppler]

Do not use a computer when teaching. Digital BT on right wrist with back-up in right pocket. Tables in head with back-up in wetnotes also in right pocket.

Sometimes use a computer when doing personal dives (caves and new wrecks mostly). Usually Digital BT on right wrist with back-up on my buddy's right wrist. Backup timing device on BT Strap. Tables in head with back-up in wetnotes in right pocket.