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Thread: Question about NAUI dive table

  1. #1

    Question about NAUI dive table

    Went to Australia last year, and was taking another look at my log book, refreshing my memory on dive table calculations. I remember having some conflicts with what I was seeing, aside from the obvious issue that it appears that the guide took us outside no-deco AND deco limits. I attached my calculations - can someone check my math? 6.28.pdf I think that will open up a few more questions from my end. I don't know why this question never came up before. The biggest issue that I can see from a safety standpoint is that [based on a boxed dive profile] the guide should not have taken us to a second 60' dive for any length of time, based on the surface interval time of only 30 minutes. And even if we had sat on the boat for 37 minutes, we should only have been able to go to 60' for the second dive, for 11 minutes MAX.

  2. #2
    Grand Poobah Founding Member
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    If those were square profile dives, your calculations look correct. But actually, you would have been past an L... but since the table doesn't show that...

    I'm sure they were going off computers - we're you on a computer? I would say there are very few profiles I have done in the last few years that would not show me a pretzel on the tables, but was fine on the computer. But at least an hour surface interval would be a much better idea.

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    Barracuda Founding Member
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    What Larry said--they were probably on a dive computer.

    Now, having said that, I would shoot for a minimum 1 hour surface interval for future safety. If I'm going to make an error, make it on the side of caution.
    John Lewis--the PlatypusMan!


  4. #4
    Thanks for checking the calculations - the guide was using a computer, and in his defense, the dive profiles were more like triangles, in that we went to depth, and then followed a slow steady ascent, such that we were only at the max depth for a few minutes. It just makes it difficult, afterwards, to make sense of the letter groups.

    Thanks again for the input!

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    Megalodon
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    Glad to see someone still does tables calculations. Keep it up. That is the nice thing about computers, they can help you extend bottom times... Did you also have a computer, or were you working tables only on those dives?

    I once saved a man in Wichita just to watch him dive...(inventor)

  6. #6
    Grouper Founding Member
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    Whats a dive table? lol!

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    Shark Zeagle Eagle's Avatar
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    A dive table is where you spread your camera gear to dry isn't it?
    --Zeagle Eagle

  8. #8
    I don't have a computer, mostly because I don't have my own gear yet. The other reason is that I value the extra measure of safety that a square dive profile affords me, and I think that I actually enjoy doing the calculations. We spent a lot of time during our entry-level NAUI training on dive tables, so I value the time I put into planning my dives (when there is no guide).

    Thanks for the encouragement, Doc!

    (USMCR Infantry - 1993-2001)

  9. #9
    Grouper
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    You also forgot, northern hemisphere tables don't work down here, you need to turn them upside down
    Any dive you survive is a good dive

  10. #10
    Megalodon
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    Reefcomber, think about this: If the deepest part of the dives was 60' and then gradually heading up, you had a fairly large, but uncalculatable (if that's a word) safety zone. Think about it, if you made a gradual descent to 57' and then a gradual ascent, your TBT is maybe 21 mintues. The rest of the dive is off gassing or sorts. You will still have some nitrogen loading in the slower tissues, but still have a huge safety margin.

    I can't do the multlevel dive calulations on a NAUI table as I can the PADI wheel, but if I do the calculation on it: If you do a dive profile of 24 minutes at 60' and then 23 minutes at 40' (I think that would be a conservative guestimate) on the PADI charts you come out as a " R" diver. A R diver would have 44 minutes of RNT upon surfacing and 30 min later you would be a K diver with a 60' RNT of 29 minutes, The same dive profile for dive 2 would have been an "X" diver surfacing (over 55 min RNT at 60') and a J diver after your 55 minute SI. A "J" diver would have 44 minutes of RNT at the start of dive 3. So by PADI and giving your last dive a 40' square profile, you would have had a TNT of 99 minutes for the last dive or a PADI group of "T" with an ending RNT of 91 minutes.

    You were close to NDL's on dive 2, but not that close. since you didn't take a hit, I can surmise that you were 1. Hydrated and 2. A smiart diver for doing safety stops.

    BTW: PADI Tables have A-Z for repetative groups. Clear as mud????

    I once saved a man in Wichita just to watch him dive...(inventor)

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