landlocked:
If i live at 5000 feet in elevation and drive (in about 2 hours) to 9600 feet to dive a high mountain lake, are there additional concerns dealing with the change in elevation in addition to the elevation itself? Would I need to wait a time before diving because of the elevation change and are there any guidlines as to how long that should be? :06:
In the PADI AOW book, their section on Altitude diving takes this change in altitude into consideration. We regularly drive from 350' elevation, peak at 8,000' elevation, and arrive at 6,500' elevation when diving Lake Tahoe. I don't remember the exact numbers to calculate this, but for us, the AOW instructions show us as a J group diver once at 6,500', and recommend the regular surface interval to get back down to an A diver. I believe this is about 40 minutes or so before the PADI tables show us as being clean for the 2nd dive. We could also skip the surface interval, and just plan a dive starting in the J group if we wanted to.
In reality though, by the time you drive the 2 hours, setup your gear, suit up, B.S. about diving with your buddies, and hit the water, you've more than likely had a long surface interval. Because of this, we don't check the tables any more. It takes us roughly 30 minutes to get from 8,000' back down to 6,500', and on a good day, another 30 minutes for short breaks before we're ready to hit the water. The same is likely true for your dives.
The numbers may be different for you, but since you're only going up 4,600', the numbers are probably really close. If you have the PADI AOW book, or another similar text book lying around, you may want to run the numbers to see how the change in altitude would affect you. I don't have my copy with me at work, but maybe someone else on the board could look it up for you.
~ Jason
