Instructor_Tom
Contributor
When diving a 32% mix using a AL 80 @ 3100 psi diving between 85-115' I get about 22-25 min before I start getting into caution zone on my computer. With a 3 min safety stop I surface with about 1200 -1400 psi.My dive partner usually does a little better than me.we're leaving a good bit of gas in our tanks.
Since running out of gas isn't the problem, how can we increase our bottom time? We would like to increase our depth too, 122-130'.
Any pointers?
Doug
your question is actually 2.
1. you have 1200 PSI in your tanks and want to use more of your gas. you need to get some advanced training and learn decompression diving. this will require 2 things 1 moving from AL to Steel tank with increased capacity and the use of an AL30 or AL40 for accelerated deco.
2. bottom mix calculation. personally I always allow a margin of error for my bottom mix of at least 10+ft while maintaining a 1.4 PPO2. for a 130ft a with a 1.4 target an EAN 28% would be the ideal mix at 1.38 PPO2, I would dive an EAN 26%. also remember that as you go deeper you have to be aware of higher levels of Narcosis so the PO2 level is just one part of the equation at depths of 130+ you should look at getting Trimix certified and add Helium to your mix. for a 130 dive I would use a 26/15 mix for 2 reasons. 1 the helium will cut the Narcosis and have me clear headed at depth to better deal with issues and to remember the dive better and 2 the addition of Helium will extend my NDL since Helium is not an absorbed gas like Nitrogen.
in a nutshell it sounds like you are ready to extend your diving into a more technical realm and the correct way to do this is to find a good qualified instructor and do it safely.
hope this helps
T
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