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Ronald D Thompson wrote:
> 
> Has anyone resolved the fact that the Rule of Thirds is often (or seems to
> be) inadequate for decompression diving?  I specifically refer to the
> observation that in decompression diving, "going" from the starting point
> to the turn-around point of a dive often (usually?) requires far less time
> and gas than "returning" from the turn-around point to the starting point
> of the dive (because of the decompression obligation).  This means, for
> example, that if one of two identically breathing and kitted dive buddies
> has a total gas failure at the turn-around point, then not both divers can
> return safely to the starting point of the dive if they are diving the
> Rule-of-Thirds!
> 
> Does anyone have a standard "fix" or "modification" for the Rule of Thirds
> (in the context of decompression diving) that he/she uses?
> 
> Thanks in advance for your responses, and apologies if this has been
> discussed earlier (I couldn't find a reference) in the Archives).
> 
> Ronald
> 
> P.S.  The only obvious way around this seeming inadequacy with the Rule of
> Thirds that I can see is for me to complete a formal (and time-consuming)
> gas-matching optimization computation using a set of obvious constraints.
> I do this as a matter of course.  However, I was wondering if someone had
> an approach that was more ad hoc (and much quicker) and less brute force
> than mine.
> 
> P.P.S.  This problem plagues me whenever I begin planning for the
> loss-of-deco-gas scenario while planning an accelerated deco air wreck
> dive.
> 
> 
> --
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Ronald: The "Rule of Thirds" is a gas management concept developed
        by cave divers to allow for safe exits from an overhead
        environment. It was never intended to account for the
        deco requirements of the planned dive.....that's extra,
        and (splash) in goes the deco bottle(s). Fancy that! D.
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