Mountain Passes

[unfathomable]

I live in a mountainous area and dive the lakes around here a lot. Does anyone know how to calculate how long I should wait to cross a mountain pass after diving. Obviously I could use the 'fly time' from my computer...but this is rather a long time to wait. What if i am only gaining 2000ft crossing a pass? Is it necessary to wait that long? Is it the amount of elevation gained that is critical or is it the total height of the pass? I'm at a loss here.

 

[rookers]

The delta between where you dove and the elevation of the pass is the critical factor. Unfortunately, I don't think there is much good data on this. I keep my computer in my seat next to me to watch it turn on and change altitudes. I don't know if it will warn me if I exceed a safe delta.

 

[nadwidny]

I live in a mountainous area and dive the lakes around here a lot. Does anyone know how to calculate how long I should wait to cross a mountain pass after diving. Obviously I could use the 'fly time' from my computer...but this is rather a long time to wait. What if i am only gaining 2000ft crossing a pass? Is it necessary to wait that long? Is it the amount of elevation gained that is critical or is it the total height of the pass? I'm at a loss here.

It's not a problem. Ever. Don't listen to those who say it is.

 

[Charlie99]

It's not a problem. Ever. Don't listen to those who say it is.

I see you are a scuba instructor. Which agency teaches that "it's not a problem. Ever." ?

 

[Gary D.]

Lots of factors to consider.

What elevation are you diving?
How close did you push the tables (computer)?
What is your surface interval prior to going over the pass?
How long does it take to get over the pass?
What elevation will you be at on the other side?

We used to push the tables in the Seattle area and head home right away. Within an hour we would be itching like crazy as we went over the 3100’ pass. Then on the down side the itching subsided and we were fine.

Per our medical people most of the bends cases we see over here are just what I described above and not from local diving. Granted we are talking sea level to a rapid 3100’ climb, then a gradual drop to 2200’ where I live

IMHO it would be best to take a meal break prior to going over the pass if you pushed the tables. Better yet don’t get close to maxing out the tables. I wouldn't go by NO-FLY times.

Gary D.

 

[Thalassamania]

I know folks who have been bent crossing mountains after diving, so it can be a real problem. The accepted technique is to use altitude tables and limit you dives to the no-D limit for the highest pass you're going to go through. Another approach is to use US Navy tables and be sure that you'fe in Group-C before you hit the pass, or breathe two hours of pure oxygen before you asend to the pass (Group N to Group A).

 

[nadwidny]

I see you are a scuba instructor. Which agency teaches that "it's not a problem. Ever." ?

The Real World agency.

 

[KazInAz]

Here's a senerio.....On Sunday I was in San Diego at the National Polytechnic College of Engineering and Oceaneering. I went on a chamber ride to 165'. I was 'at depth' for maybe 3 min. Total 'dive' time was 33 min. 100% O2 from 60ft up with air breaks as instructing by chamber operator. I'm not sure of the timing the on/off 02 but I was saturated and buzzed for about an hour after. After a 10min observation period and a further 10 min gab session we headed home. Our 6 hr drive included going over a 4000 ft pass. I was fine. The chamber operator was aware of where we were going after the ride. The pass is about an hr into the trip. He said I would not be down long enough for it to matter and I would be saturated with O2. He's an instructor at the College and I took his word for it. All was fine and I had a blast! Major narcosis at 155ft.

 

[Gary D.]

Lets not forget Hydration and Physical conditioning in this as well.

Activity that would be fine for a well fit and properly hydrated person could kill someone that was dehydrated and out of shape.

Gary D.

 

[sbrooks]

I agree with Thalassamania...

I use the NOAA Ascent to Altitude Table.

S.