Posted by MHK on April 06, 2001 at 10:27:14:
In Reply to: Re: A word on computers. posted by Steve on April 05, 2001 at 19:31:19:
When we do the Moody we no longer use air.. Our team approach is to never exceed an END of 100' and as such we would normally run a hyperoxic trimix of 25/20..
By doing this we keep our END's at 94' and our P02's at 1.39. We never exceed 1.4 for the working portion of the dive. We also plan the Moody as a 150', even though there is only a few spots you can get to 150'.. Certainly the P02's and END's are more favorable because for the most part we are at 140' and thus we have a safety cushion built in..
My copy of DecoPlan is on my home computer and I'm at work so I will run profiles over the weekend and post them on Monday..
But as for an overall discussion point I would have started your diving day with a hyperoxic trimix as your back gas and then *topped off* with air for the second and third dives. The Moody is NOT a dive that should be done on air and you had the opportunity to plan for the 1st dive before you got to the boat. The Moody is not to be taken lightly.
Furthermore, we always have a team of support diver's that meet us at 70'. We use 70' because should we decide to use a deco gas other than pure 02 we would use 50% 02 and as such 70' is the MOD. I have recently been experimenting with adding 25% to that mix and have noticed I feel much better after the dives and as such I will be moving to straight Heliox at 70'.
In the alternative, we would also incorporate deep stops. Our team would all have the same deco gases and we would plan ahead if we were going to be using 50/50 and/or 100%.
I'll supply several profiles that show the differences when using 100% -v- 50%. Frankly, given the relative shallow 150' ceiling in terms of deco dives the differences are immaterial and only amount to a few minutes added deco time.
The important thing to note is that we keep our END's at 100', our P02's at 1.4, we operate as a team and we make sure we have safety diver's meeting us at 70'..
When diving the Moody I generally use AL 80's with a AL 40 deco bottle[s] and our bottom times range between 30 - 40 minutes and we're out of the water in 60 minutes..
Hopefully that will shed some light upon our approach to a dive of this nature..
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