Damselfish
Contributor
not off on your tables as in accuracy - off as in the tables will say you should already be bent.Meng_Tze:
computers and dive tables
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Damselfish:
That doesn't mean your tables are useless. It just means that you need to _think_ and hopefully you've learned alot about nitrogen loading, your profiles on dive one and the resulting available NDL on dive 2, in your previous dives.
I had a computer go sideways on a boat dive recently (on entering the water for dive one) they were multilevel dives (80 fsw for 43 min and dive 2 - 75 fsw for 61 min). I wouldn't recommend doing this without having paid careful attention to previous dives and continuously learning though :no
yes you are going to be off on your tables....but I would venture to say that if correctly using the tables... you would be off on the conservative side of things....
Charlie99
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I think what Damselfish is saying is that tables are limited in value for backing up computer dives, since many valid non-deco computer dives far exceed table limits.Meng_Tze:
As I noted earlier in this thread, my dive log is full of 100' 65 minute dives that never went into deco. That, as Damselfish said is "way off the table".
My fallback position for a dive computer failure after one or more non-deco dives is to assume I am in pressure group Z of the PADI RDP and to plan my surface interval and future dives based upon that.
cummings66
Contributor
Meng-Tze I think that you're misunderstanding what several of us have said.
If you dive a computer, and I have several 100 foot or deeper dives that exceed 50 minutes and a couple that exceed an hour then you simply can not put that dive to a table. Every single table out there will say you're bent and to go home, no more diving allowed. How can you use a table to plan additional dives when you're already bent according to the table? Remember we're using tables to plan in the manner they're taught.
A table can NOT back up a computer if you use the computer to it's full advantage. That is, I do a dive to 100 feet for a few minutes and ride the ndl all the way up to 30 feet. You'll get way more bottom time doing that than any table would dream of giving you.
Now a table can be backed by a computer but not the reverse in all cases. That is what we are saying.
I used to log every dive when I first got a computer and figure out the pressure groups and everything. Then one dive I noticed that the tables said I was done, the dive I finished was not possible, by a HUGE number. Not only did I violate the tables they were so violated that the plastic card melted. My computer however was perfectly happy because on that dive the majority of it was at a shallow depth.
If you think the NDL is all we worry about then look at your O2 clock on a computer vs on paper. Tables can never backup a computer. If you dive with a computer only another computer can be used as backup. Unless you use the computer to backup your tables in which case your tables never got violated in the first place.
If you dive a computer, and I have several 100 foot or deeper dives that exceed 50 minutes and a couple that exceed an hour then you simply can not put that dive to a table. Every single table out there will say you're bent and to go home, no more diving allowed. How can you use a table to plan additional dives when you're already bent according to the table? Remember we're using tables to plan in the manner they're taught.
A table can NOT back up a computer if you use the computer to it's full advantage. That is, I do a dive to 100 feet for a few minutes and ride the ndl all the way up to 30 feet. You'll get way more bottom time doing that than any table would dream of giving you.
Now a table can be backed by a computer but not the reverse in all cases. That is what we are saying.
I used to log every dive when I first got a computer and figure out the pressure groups and everything. Then one dive I noticed that the tables said I was done, the dive I finished was not possible, by a HUGE number. Not only did I violate the tables they were so violated that the plastic card melted. My computer however was perfectly happy because on that dive the majority of it was at a shallow depth.
If you think the NDL is all we worry about then look at your O2 clock on a computer vs on paper. Tables can never backup a computer. If you dive with a computer only another computer can be used as backup. Unless you use the computer to backup your tables in which case your tables never got violated in the first place.
cummings66
Contributor
Charlie99:
That Charlie is the Gem in this thread.
plot
Contributor
cummings66,
I completely 100% agree with you. I think alot of the people here are confused as they normally dive in salt water areas where you have a square dive profile everytime so the tables will match the computer very closely everytime. Alot of us freshwater guys dont have the luxury of that so we end up hitting deep spots, going shallower, deeper again, etc. depending on the terrain of the body of water we're in. Alot of our dives go over a wall to a certain depth then come back up to 30 feet or even shallower and still be swimming along the bottom. This completely screws any table.
I completely 100% agree with you. I think alot of the people here are confused as they normally dive in salt water areas where you have a square dive profile everytime so the tables will match the computer very closely everytime. Alot of us freshwater guys dont have the luxury of that so we end up hitting deep spots, going shallower, deeper again, etc. depending on the terrain of the body of water we're in. Alot of our dives go over a wall to a certain depth then come back up to 30 feet or even shallower and still be swimming along the bottom. This completely screws any table.
plot:
What was the problem? I have a friend who got certified with SSI a while ago (maybe 8 years ago?), and I looked at her dive table. IMO, my PADI table is much better organized, but they are very similar. Her table only went to something like 80 feet though.
Cummings: You need to think through the scenarios a bit ...
Just because you can't do a "multilevel computer dive" and somehow match a table exactly you think that tables aren't useful. That's very limited thinking. If you have a 1 hour SI, after one of your hundret foot dives, how much NDL will you have? Is it fairly consistend on your computer. If your computer died after dive one, you couldn't work out what pressure group to use to plan your next dive?
Plot: I'd say that some people here are not confusing anything.
Just because you can't do a "multilevel computer dive" and somehow match a table exactly you think that tables aren't useful. That's very limited thinking. If you have a 1 hour SI, after one of your hundret foot dives, how much NDL will you have? Is it fairly consistend on your computer. If your computer died after dive one, you couldn't work out what pressure group to use to plan your next dive?
Plot: I'd say that some people here are not confusing anything.
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