Best Safety Stop Depth
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bamamedic
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Well, then....guess I've been doing it wrong all this while, 'cause I hold my safety and deco stops in a horizontal position....LOL
Anyone interested in the safety stop issue might also be interested in this recent thread for an excellent discussion about the topic.
However, since a previous post in this thread listed NAUI's position on half-stops at the time, i.e. 1 minute half stop, 3-5 minutes shallow stop. It's worth noting here that, based on the research, NAUI is now updating their recommendation to 2-3 minute half stops and merely a 1 minute shallow stop.
I'm not sure what NAUI recommends for ascent rate, but one thing that seems clear from these recent studies is that the idea that a super-slow ascent is always safer is simply NOT supported by the evidence. In fact, in at least one of the studies (sorry can't find the link right now), the slowest ascent rate actually rendered one of the higher microbubble counts of all the ascent rates. It looks to me like a moderately-fast "stairstep" ascent with half stops is evidently a better way way to reduce microbubble formation.
Anyway, below is the proposed NAUI revision (bold emphasis mine), based on the recent Bennett, et. al. studies:
>*< Fritz
NAUI Rule of Halves Revised
Based upon the most current research and analysis of decompression science on the value of deep stops in "no-required-decompression" diving by Bennett et al (Undersea and Hyperbaric Medicine 2007; 34(6): 399-406, the NAUI Board of Directors approved a change to the NAUI Standards and Policies on March 7, 2008, at its annual meeting. A reprint of the study is included in this issue of Sources (pp. 48 ff).
The membership is advised to make a pen and ink change in their personal copy of the manual and mark both the title page and changed page with "rev. 1-08". Notice of these changes is included in existing inventory of the NAUI Standards and Policies Manual, and the changes will be incorporated in the next printing.
S&P Page 2.16 Current wording
It is recommended that following dives in excess of 40 feet (12m), divers make a one minute stop at a depth that is half that of the deepest depth reached during the dive and make a precautionary stop in the 10-20 feet (3-6m) zone for three to five minutes before returning to the surface. The precautionary stop time may be considered "neutral time" - not counted as either dive time or surface interval time.
S&P Page 2.16 Changed wording
It is recommended that following dives in excess of 40 feet (12m), divers make a two to three minute stop (with two and one-half minutes being optimum) at a depth that is half that of the deepest depth reached during the dive and make a precautionary stop in the 10-20 feet (3-6m) zone for one minute before returning to the surface. The precautionary stop time may be considered "neutral time" - not counted as either dive time or surface interval time.
However, since a previous post in this thread listed NAUI's position on half-stops at the time, i.e. 1 minute half stop, 3-5 minutes shallow stop. It's worth noting here that, based on the research, NAUI is now updating their recommendation to 2-3 minute half stops and merely a 1 minute shallow stop.
I'm not sure what NAUI recommends for ascent rate, but one thing that seems clear from these recent studies is that the idea that a super-slow ascent is always safer is simply NOT supported by the evidence. In fact, in at least one of the studies (sorry can't find the link right now), the slowest ascent rate actually rendered one of the higher microbubble counts of all the ascent rates. It looks to me like a moderately-fast "stairstep" ascent with half stops is evidently a better way way to reduce microbubble formation.
Anyway, below is the proposed NAUI revision (bold emphasis mine), based on the recent Bennett, et. al. studies:
>*< Fritz
NAUI Rule of Halves Revised
Based upon the most current research and analysis of decompression science on the value of deep stops in "no-required-decompression" diving by Bennett et al (Undersea and Hyperbaric Medicine 2007; 34(6): 399-406, the NAUI Board of Directors approved a change to the NAUI Standards and Policies on March 7, 2008, at its annual meeting. A reprint of the study is included in this issue of Sources (pp. 48 ff).
The membership is advised to make a pen and ink change in their personal copy of the manual and mark both the title page and changed page with "rev. 1-08". Notice of these changes is included in existing inventory of the NAUI Standards and Policies Manual, and the changes will be incorporated in the next printing.
S&P Page 2.16 Current wording
It is recommended that following dives in excess of 40 feet (12m), divers make a one minute stop at a depth that is half that of the deepest depth reached during the dive and make a precautionary stop in the 10-20 feet (3-6m) zone for three to five minutes before returning to the surface. The precautionary stop time may be considered "neutral time" - not counted as either dive time or surface interval time.
S&P Page 2.16 Changed wording
It is recommended that following dives in excess of 40 feet (12m), divers make a two to three minute stop (with two and one-half minutes being optimum) at a depth that is half that of the deepest depth reached during the dive and make a precautionary stop in the 10-20 feet (3-6m) zone for one minute before returning to the surface. The precautionary stop time may be considered "neutral time" - not counted as either dive time or surface interval time.
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