elevation changes?

[TNdiver]

The elevation where i am from is around 1700-1900 feet. I have always heard that there is more oxygen in the same volume of air as you get closer to sea level. Is that enough to make any noticable difference in my dive time here to my dive time sealevel? and if so any rough idea how much?

[Bill]

TNd
In theory, the density of air (or O2) changes about 2%/1000 ft. Since the temperature in your lungs is fixed, about half of that change disappears and only about half of your useable O2 is in your lungs. My guess is a difference of less than one second per minute. After hundreds of statics at 6000 ft or so, it seems to be noticeable but too small to measure.
Aloha
Bill

[Walrus]

Yep, what Bill said.
I live and train at 2100 ft, the difference in perfomance between here and sea level is small. I think I used to gain 5-10 seconds on my static at sea level vs at 2100ft, but it could have been a mental thing too. Also I didn't use packing then. Although debated on another thread I still think that packing does offset the altitude difference to some degree.

I recently went in a pool competition in NZ, was at 1200ft. We had 3 guys do 175m+ dynamics, and Suzy Kensington did 163m. So no one seemed hampered by the altitude.
We are talking of altitudes of 1000->2000ft I think the differences are very small. At serious altitudes ie 9000ft+ then I would say yes you will definitely start seeing some significant perfomance losses.

Cheers,
Wal

[TNdiver]

thanks for the input guys. Thats one of those things that really doesnt matter anyway because it is how it is and it really cant be changed, i was just curious, and im really anxious about my first trip , so ill probably be asking alot of weird questions like this before July 12th gets here. I have another question. I have read that you can swallow to equalize, but that its hard for some people. I dont seem to have any problem doing it on land (ill explain how im getting the pressure in a sec.) the only problem im running into is that one of my ears doesnt work as well as the other, but i think i may just be stopped up. I read in another post here that if you plug your nose then swallow you can build pressure in your ears. I found it works better to plug your nose then create a vaccume in it, then swallow and the pressure in your sinsus will transfer to your ears. Then i can work on equalizing techniques with out needing deep water. The question is would there be any reason i would have a harder time with that in a deeper dive than just sitting around? The deepest pool i have around here to train in is only like 14 feet, and i'd have to pay to get in there. I have a friend with a boat, so i may try to get him to take me to the lake to try it just to be sure. I dont want to count on one way of doing it too much and it not work out for me during actual dives. I think i have rambled enough for one post, so ill end this one here.