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Hi, In response to your question regarding procedures when having to perform an emergency ascent and/or rescue during a decompression dive, I would like to inform you of how the rules at the BEFOS (Belgian Federation for Underwater Research and Sport), affiliated to the CMAS (Confederation Mondiale des Activites Sous-Marines) stipulate what to do in such a situation. First, we differentiate between a deco and Non-deco dive. On a dive which has NO decompression requirements (other than the usual safety stop of 5 minutes at 3 msw/10 fsw), the procedure in case of an emergency ascent is straightforward; after a MAXIMUM of 5 minutes at the surface, one redescends to 3 msw/10 fsw and performs a DECOstop of 5 minutes at that depth. Or, if you like, the safety stop. Now, concerning a dive where you NEED to do decompression , the story is a little different. After a MAXIMUM of 5 minutes at the surface (enough time to signal a boat, in case of a rescue to make sure the victim is safely handed over to the surface safety crew, and grab an extra stage bottle or whatever, one hopes...) one redescends to the depth of the DEEPEST required DECO stop, and does all the required stops, but the deco-time at each stop is MULTIPLIED BY 1.5. In your example ( bottom time of 40 minutes @ 40 msw/130 fsw with a decompression schedule of 5 min @ 12 msw/40 fsw, 8 min @ 9 msw/30 fsw, 17 min @ 6 msw/20 fsw and 27 min @ 3 msw/ 10fsw.) this would give us a decompression schedule in the case of an emergency ascent/rescue during this dive (or indeed, during the execution of one of the DECO stops !) of: 7.5 minutes @ 12 msw/40 fsw, 12 minutes @ 9 msw/30 fsw, 25.5 minutes @ 6 msw/20 fsw and last but not least 40.5 minutes @ 3 msw/10 fsw . This constitutes a total of 85.5 minutes DECO (where normally only 57 minutes were planned). In the extreme case that you had to surface during your 3 msw/ 10 fsw DECO , this would mean that you had to do the whole procedure over again, the full 85.5 minutes. This looks rather ridiculous if you consider the lengthy decompression involved, but rules are rules, and I'm sure they are properly founded. SYIH Adri. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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