Do you carry tables with you underwater...why?

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gcbryan

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I read posts every now and then when it's mentioned that someone carries recreational dive tables with them underwater. Why?

In some cases the reason mentioned is in case the computer fails. If this happens so does the time and depth function and having the table will not resolve that.

Maybe they carry a separate time and depth gauge but then you don't know what letter group you are in or were in before the dive if you've been using a computer.

If it is simply just to be able to look up the NDL for a single dive (for example 20 minutes at 100 feet) it's simple enough to either memorize the table or just use the 120 rule or other short cuts so I'm curious what exactly is the scenario where you feel it's useful to have the table with you underwater.

Maybe I'm misreading the posts...entirely possible!
 
I dont get it either. 60ft 60 minutes the rule. Are we over thinking this wh=ole issue?
 
I think most were stating the tables are a back up to the computer (or vice versa) in terms of dive planning, not actually used during the dive.

Computer fails on dive #1. If you have a back up SPG and a watch, you're all set. In fact, you don't even need the watch if your buddy's computer is functioning. Time is the same regardless of who keeps it. Diving tables just mean much more conservative diving for your remaining dives.

I didn't see the post in which someone said they take it with them into the water.
 
Gray -- No, I don't think you are misreading the posts but I do sometimes wonder how true they are. I've said it before, and I'll say it again, I believe the time spent on "learning the tables" is time pretty much wasted -- NOT because learning about decompression is not worth the time (it is) but because spending the time on the tables doesn't really teach that much about decompression. (Not to mention that decompression is NOT that much of a problem for the new OW diver -- but I digress.)

I think the tables are stupid. (He writes after spending several hours this afternoon working with two students on table problems!)
 
No, if your'e on computer & it fails--you've probably already busted them.....I'll take my chnaces that my computer hangs in there---if not, head to my partners arm---bet I come back alive & well.........
 
i used to carry tables with me, but the 120 rule is just so easy when you dive 32% nitrox ...

basically, your max depth and time should not go over 120

for example, if you're at 70 feet, your max bottom time will be 50 min

and if you're at 80 feet, your max is 40 minutes, and so on
 
I read posts every now and then when it's mentioned that someone carries recreational dive tables with them underwater. Why?

In some cases the reason mentioned is in case the computer fails. If this happens so does the time and depth function and having the table will not resolve that.

Maybe they carry a separate time and depth gauge but then you don't know what letter group you are in or were in before the dive if you've been using a computer.

If it is simply just to be able to look up the NDL for a single dive (for example 20 minutes at 100 feet) it's simple enough to either memorize the table or just use the 120 rule or other short cuts so I'm curious what exactly is the scenario where you feel it's useful to have the table with you underwater.

Maybe I'm misreading the posts...entirely possible!

Yes I carry tables but I wouldn't call them recreational tables. I always keep a standard set of US navy dive tables in the clear pocket on my halcyon wetnotes. Of course those only cover air and are not necessarily conservative but they are durable and convenient.

For non-recreational dives I carry custom cut tables off V-planner which include the planed dive and contingency tables to cover lost gases or different bottom times.

On those dives I dive the tables and use the computer as a backup and I no longer have a computer for recreational diving so I use a bottom timer and the tables only. Eventually I plan to replace my recreational computer but right now this works fine.

But I dont necessarily follow tables either. I pad things like my last 2 stops and add stops on the fly based on how I feel or whats going on. I also generally stay at the last stop or a safety stop until I hit a convenient time so I dont have to add odd numbers together later.
 
Diver 85 is right. I parallel plan my computer dives with the tables when possible. On wreck dives (or other relatively square types of dives) it is possible to stay on tables even with a computer depending on what type of cylinder you are using. I write my NDL on my hand with a pen for that profile, so I do not need to remember the number. Once I know that I am off tables (usually by the second repetitive dive) then I plan to abort the dive and follow the computer manual's rules for what happens if the computer breaks. In my case, that is to ascend normally and not dive for the rest of the day.

Other than that, I keep PADI, NAUI, and Navy tables in my bag for the people on charters who do not know that their computer battery needs to be replaced ever so often. Then again, those people normally do not know how to use tables so that is typically a moot point.
 
No, I don't carry dive tables, if I am doing a more relaxed non deco dive I just know the NDL (and they are also written in my divewatch wristband, just in case my memory decide to make jokes with me...) and all I need is my depth gauge and botton timer, if it is a deco dive, the I will have all dive carefully planed and I follow my plan, which should be, as safety precaution, written in my slate.

Never happened, but if for some reason I have to "improvise" a deco, a good idea is starting from half the max depth follow something having as a guideline the fibonacci sequence (1, 2, 3, 5, 8, 13... following number is the sum of the previous two numbers) for each 3 meters of ascent, not necessarily the exact sequence itself, you can shorten the longer numbers, the full sequence usually would be way too much for just an emergency improvisation, if you have an unplanned deco obligation even close to the actual sequence, then you really screwed up, you should have planned it better.
 
I also used to carry tables (Navy) with me underwater (during years that I did not have a computer, and for the first year that I did have one), then finally realized I was never in a situation to use them (underwater)... deco dives were always pre-planned, and now are ancient history for me.... for my current easy rec diving I still carry a set in a dive bag "just because" (old habits die hard).

Best wishes.
 
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