Using tables as backup to computer

[SNorman]

If you dive using a computer but use tables to calculate your pressure group if or when your computer goes bad, do you use the entire time reported by the computer or do you make note of what time you began your ascent and use the shorter time?

 

[Blackwood]

Use your table's definition of bottom time.

That said, unless you dive square profiles, you may not be able to immediately continue unless you (a) take mental notes about your profile throughout the dive/day and (b) understand how to figure deco for multi-level dives.

 

[underwasser bolt]

If my computer fails (it never has) I would use my watch for bottom time and last known depth (I carry a watch with depth readout just for this emergency). at that point I would calculate a square profile using tables.

That said, being familiar with a worst case deco procedure for your dive could be worth knowing.

 

[1_T_Submariner]

On alot of dives that I do the tables would just tell me to sit out for 12-24hours. I carry a spare computer in a BC pocket. Since it is air only I pull it out and clear it's obligation if I'm diving Nitrox (It usually turns my safety stop into 7-8 minutes)

 

[jgeldin]

I recently dove PADI tables when I had my Atom 2.0 in for a warranty repair. I followed the table definition of bottom time and always calculated from my max depth, making no calculation for multi-level (I don't have a wheel). Since I was shore diving in local reefs my depths never got below 40fsw.

 

[Twiddles]

You use your buddies computer, because you were together the whole time and your buddies profile is your profile.

 

[ItsBruce]

I check my computer often enough that if it goes out, I still won't have any deco obligations and I will do a safe ascent with a safety stop. Then I'm done for the day. Sure I could use the tables, but I see no reason to run the risk of diving based on my best recollection of my profiles for the day.

 

[diver 85]

If you dive using a computer but use tables to calculate your pressure group if or when your computer goes bad, do you use the entire time reported by the computer or do you make note of what time you began your ascent and use the shorter time?

I'm thinking you must do everything the 'old fashion way' if you want to rely upon tables ie BT the way it was taught with conventional tables use......Otherwise your NDL calculations are off, table wise.........

 

[Walter]

You use your buddies computer, because you were together the whole time and your buddies profile is your profile.

That's dangerous. Your buddy's profile is similar to your profile, but they are never the same.

 

[String]

Treat the entire dive as a tables dive.

Note the time you got in the water (you DO have a backup timing device and DID remember to zero the bezel or start it didnt you?)
Then use the max depth off your depth gauge (you DO have one yes?) to work out the schedule from the backup tables (Which you ARE carrying in your pocket of course...)

You may have a little less bottom time or more stops but its safe.

Note:- You'd need to know your starting group prior to the dive but in any case, you should be doing that as a matter of routine.

If a computer dies underwater i wouldn't trust ANY information off it, not the time, the depth or anything. It may not be true so its time to use the backup gauges.