altitude diving questions

[yojinbukai]

Okay guys... question for ya'.

I'm a nitrox diver and was absolutely taken aback today when I picked up my filled cylinder. It handi-oxed at 36.4 so I rounded up to 37. The chart at the dive center said that my MOD was 67 feet without violating 1.4 ATA.

I don't have altitude tables that I trust ( I have downloaded one from the net just for curiousity ) and haven't had an altitude class. While my Genesis Resource is supposed to take altitude into account automatically, I figure Mr. Murphy is diving with me and want to plan my MOD and BT according to accurate tables before entering the water.

If someone smarter than I am on this could figure out my numbers based on their altitude tables, I'd be much obliged.

My altitude is 4360 and I live here so pre-dive on site time is maxed out.

I suppose that with the PPO2 being less to start with, breathing the 37% mix could get me to the CNS limits pretty quickly. Heck, when we calibrated the handi-ox it was at 19 or 20 instead of 21, so I suppose there is that much difference in the Partial Pressures up here.

I'm thinking that getting into an altitude class before doing anything deep or long is a smart thing so I may just end up working on my skills and neutral bouyancy at 20 or 30 feet for now.

Thanks in advance fellas.

[Saw7616]

My Suunto tells me 37% 1.4 mod 88ft.

I can set it to 5000ft but, it doesn't show in dive mode... Let me check the planner and see if it will give me a shot at Bottom Time

80 feet approx 40 mins no deco... That's probably have you right at 1.4 pO2

I also checked the Navy Nitrxo charts that I have but, they don't adjust for altitude.

Ran the same plan without 5000 alt adjustment.

53mins no deco

[Gryfen-FL]

--Saw....I don’t know if you have an altitude cert. or not.
--Yojinbukai....I not making any assumptions on your research or experience level. I don't know how rough the country you will be in is.


Disclaimer:
I am relatively new to diving. No altitude class, yet. I got a 'quick & dirty' in my NAUI Adv class, and have looked into it on my own.Some things that I didn't immediately consider kind of startled me and I think they're worth mentioning for GP:
1: Most depth gauges are manufactured to work with sea level as a "0" point. When you are starting a dive at a significant altitude, your gauge will read shallower than your actual depth.
2: Consider the terrain. The altitude changes involved in the drive home could be a point of concern.

Again, sorry if this is elementary to you guys.

Ref:
--1: Sources Sept/Oct 1994 (http://www.mundofree.com/zco/tayloraltitude.html)
--2: Doogle (http://www.google.com/search?q=%22altitude+diving%22+%2Bnaui+%2Bgauge&btnG=Search&hl=en)