Maximizing depth AND time under

[selytch]

I'm 99% certain B&B on Maui can blend you any % of nitrox you want. I'm pretty sure I even saw that they do trimix when I was there. Since you will obviously know your dive plan, just get a blend that works with your dive(s) for that day.

They also offer IANTD course I will probably take and Brad and Blesi are really nice people in general. No financial affiliation with them whatsoever.

Thanks again for the input! I do realize physics and so on, but there are different dive profiles that can be tried. It boils down to this - testing different rates of ascent, descent and bottom time as well as ascent/descent profiles.

 

[selytch]

Read up on Rock Bottom (NWGratefulDiver has a great article online) and you will very quickly see that when you end the dive with an empty tank as you are trying to do, your safety margin is not nearly high enough.

Know your rock bottom number for 120ft (calculated using the sum of yours and your buddy's SAC since they'll be breathing off your octo). I suspect you're finishing the dive with about the right amount of air to get you and your buddy up safely in case of total gas loss.

If you still have extra air that you want to use, options include nitrox, dive computers, or getting a recreational deco cert.

I looked at the website, thanks! Nice write up on rock bottom time and air consumption. I was put off however by his article on solo diving - better he takes it off website. If one asks "Am I ready for solo diving" the answer is "probably not"...

 

[aquaregia]

If one asks "Am I ready for solo diving" the answer is "probably not"...

If someone doesn't bother asking themselves, they're likely a cocky six-monther on the checkout train.

 

[selytch]

If someone doesn't bother asking themselves, they're likely a cocky six-monther on the checkout train.

You are saying the same as I do - one has to ask her/himself, do research and consider technical class - rather than walking around and asking PADI/NAUI instructors about their "readiness".

 

[TSandM]

I think it's important to recognize that rock bottom is a dynamic thing during a dive -- you do not have to reserve 40 cf of gas when you are in 20 feet of water, at the end of the dive. As I move off my deepest depth, my gas reserves decrease. Burning a tank down to 500 psi in 10 feet of sunlit water is not an unreasonable thing to do at all. There may be some circumstances (diving in kelp, rough surface conditions, etc.) where you might want to keep more gas in your tank to deal with surface issues, but for example, here in Puget Sound, I took a tank down to about 300 psi on a day with 70 feet or more of viz -- but the last ten minutes of the dive was spent chasing an egg yolk jelly in about six feet of water, trying to get the perfect photograph. I was willing to take chances with an inaccurate SPG, where the answer to being out of gas was standing up!

 

[SlicerDicer]

I'm 99% certain B&B on Maui can blend you any % of nitrox you want. I'm pretty sure I even saw that they do trimix when I was there. Since you will obviously know your dive plan, just get a blend that works with your dive(s) for that day.

AFAIK they do classes for it too. I am not sure talk to brad

 

[scubadiveilat]

What air mix are you using?

 

[selytch]

What air mix are you using?

air for 120+ ft.

 

[rjack321]

air for 120+ ft.

You don't want to dive nitrox, come up shallow (<40fsw), or go into deco. You are pretty much asking for the impossible.

 

[aquaregia]

I'm not sure why the goal is to use every cubic foot of gas in the tank either.