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>From: cpitts@ga*.te*.bt*.co*.uk* (Chris) >Date: Thu, 29 Apr 1993 13:46:04 +0100 > >Hi > [intro-intro deleted] >First of all, a brief introduction... I've been diving now for 7 >years, and have done goodness knows how many dives under varying >conditions, most of which have been on the South Coast of the UK and >in the North Sea (yep - the North Sea really does turn blue. Just >ten...). This is something I don't understand (but then again, English is not my native language). The North Sea as I know it looks more like my grandma's potato soup :-) [rest of intro deleted] >physics/biology of diving is limited. However, having recently >(accidentally !) discovered that the RNPL/old BSAC deco tables ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ please elaborate ! >(based on the Haldane model, I believe ?) are potentially >dangerous, >Intro over. Now a question for the decompression modellers based >loosely on the recent thread of repetitive diving. The old RNPLs >put a no decompression limit at 9m, other tables put it at lower >limits (5 m on the BSAC '88s/Buhlmann ? - I haven't got any tables >handy). > >Based on current knowledge, what is the safe depth to carry out >numerous ascents (eg lots of training drills) ? Please note, I'm >not looking for what the tables say (I can read tables - honest !). >I'm trying to find a definitive answer based on knowledge, >experience and gut feeling. The dangers at these shallow depths do not arise from the chance of exceeding no deco limits, as these are way beyond the time your airsupply will allow you to dive. Potential problems come from ascending too fast (see note below!) and bounce diving (diving frequently to shallow depths, with minimal or no surface intervals) which may cause (micro)bubble formation. > >Also, can anyone advise me on just how the Haldane model fails >in layman's language. Is it safe to use the RNPLs under restricted >conditions ? (Eg, depth limit of 30m, no repetitive dives, 10 m/s >ascent rate etc). ^^^^^^^^^^^^ ^^^^^^^^^^^^ I'm (almost) sure you didn't mean to say this, but recommended max. ascent rate is 1 ft/s or 18m/min. It would be wise however to stay well below this limit. My Suunto Solution divecomputer indicates ascent rates of 3-6-9 m/min, and gives an audible alarm if you ascent faster than 12 m/min. More details on the Haldane model I leave to others more knowledgeable on this subject. [rest of message deleted] ciao, Han ----------------------------------------------------------------------- IIIII CCCCC TTTTTTT Han Weegink info only I C C T ICT Automatisering Deventer BV I C T Aerospace Group Holland I C T E-mail: weegink@ic*.nl* I C C T Telefax: +31 (0)5700 21362 IIIII CCCCC T TelePhone: +31 (0)5700 33888 -----------------------------------------------------------------------
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