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#1
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Dives to 160-165 ft
A bunch of us were sitting around planning dives last night and the subject of standard mixes came up.
When planning dives in Deco Planner to 160 the ppo2 for 21/35 is 1.23 and for 18/45 the ppo2 is 1.06. I know for the working part of the dive we keep the ppo2 to a max of 1.20. But for this depth the 21/35 gets you out of the water faster. Is the minimal increase in the ppo2 that big of a deal? Also the difference in END, CNS and OTU's is minimal. Are there any reasons, other than the pp02, why 21/35 is not an acceptable gas for a dive to this depth?
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"Pfft, F%$k that, Wreck scoooter!!!!" J Groff. |
#2
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21/35 range is 130' to 160' with an MOD of 190
18/45 range is 170' to 200' with an MOD of 220 So diving to 165' on either gas would be a matter of choice but splitting hairs really...Who plans to 165 and not just 170 or 160? BTW, why was I not invited to this dive planning party? Last edited by Jay Roy; 01-23-2009 at 01:10 PM. |
#3
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If I am doing this correctly, and you do the calculations, MOD of 21/35 at PP02 of 1.4, is 186 fsw. If you do it for 1.2, it's 155 fsw.
What calculations were you using, Joe? |
#4
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Thanks Jay.
I told John we always plan for 10 ft increments anyway so 160 or 170. We were talking about doing "G" and the St James etc and got on the subject of gases. I liked the 21/35 schedule better and that is where the questions came from. I agree we are splitting hairs with this example. We are going to continue the planning Sunday after the dive if your interested. Quote:
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"Pfft, F%$k that, Wreck scoooter!!!!" J Groff. |
#5
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Looks right to me...
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#6
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Quote:
You could call it 150, 30 min bottom time, 30 mins deco...Go back, have lunch at the Barcelona Cafe Last edited by Jay Roy; 01-23-2009 at 01:24 PM. Reason: Added info |
#7
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Deco Planner. I don't think Deco Planner considers O2 narcotic. When you run the numbers through you get 21/35, pp02 1.23, MOD 187ft at a depth of 160.
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"Pfft, F%$k that, Wreck scoooter!!!!" J Groff. |
#8
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Yepp I had 160-165 on the St James. Thats probably where we got the 165ft from.
Quote:
__________________
"Pfft, F%$k that, Wreck scoooter!!!!" J Groff. |
#9
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Gas ranges changed recently according to GUE:
21/35 100-150 18/45 150-200 At least, this is according to the Tech1 course I was able to sit in recently. What you do, is, of course, entirely up to you and the team.
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Oren Your Waterloo region DUI contact person but I'll talk to everyone, who wants to get into DUI and needs help. |
#10
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The MOD are different when using these standard gases for deco purposes. Generaly, we use 1.6 PPO2 for deco gases above 100 feet and 1.4 PPO2 for deco gases bellow 100 feet. Some dives may require changes. Deep deco gases may require a lower PPO2 du to CNS and OTU's which does not really affect us as we don't du these 25 hr epic dives like they do in Wakulla. Steve |