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There is no doubt in my mind that the computer had a fault or that it was mis read during the dive as it was a strange bit of kit.
I ran the profile on my Vytec
37m for 42mins allowing for ascent and 8min stop is aproxamatly a 30min bottom time;
On air thats 37mins deco
No Nitrox 30 running a PP02 of 1.4 thats 22mins deco
Surface intervall of 2 hours
31m for 40 asuming deco and ascent time again bottom time
30mins
31m 30mins on air 53mins deco
31m 30mins on 30% Nitrox 19mins deco
Running the profile on Deco planner using 35 80 gradiant factors gave 24min and 19min on Nitrox 30 and runing it on air came up with 49min and 42min deco
All in all the profile dosent make sence. I can only asume that it was a multy level dive with the vast majority of the dive at a much shalower depth. I ran a few profiles and to get 8 mins deco on air for the first dive you coud do 5 at 37, 5 at 30, 10 at 25, 10 at 20, On a 30 85 that came up as 9mins of stops.
Please note that was Normal settings and safety off
I would be a bit more conservitave given the conditions surounding this dive.
This is NOT a slag off. This is just pointing out that the figurs dont add up so there must be more to the profile than I have read or the computer is buggered.
Now I dont normaly cut tables for a no deco dive BUT I do check out the dive plan on the PC before the trip so I dont sudenly find that my planned bottom time is going to be well into deco. I also carey INTD bail out tables so even if my computer gos tits up I have some form of get home plan. I offten dive the computer even on serious multi gas dives but I always have a mentle picture of the profile in my mind before the dive so when my computer shows me garbage I will / should notice it.
If I am over seas I dive two computers if I cant get to a PC to plan the dive and do a rough profile on the IANTD tables.
Computers are good but they have to be monitered cairfulley coz all things electrical are the acursed spawn of the devil.
Mark Chase
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