Driving over mountains after diving?

[supergaijin]

Planning as though it where an altitude dive is a good approach.

That rings a bell. This is the diving area (sea level). We planned our dives assuming they were at altitude and factored in the cold. Thus we did 2 dives to a max depth of 18m for a bottom time of x mins (can't remember and don't have a table handy). We eventually factored an extra 4m for altitude and 4m for cold, thus we were planning 2 dives to an adjusted max depth of 26m with a surface interval of 90mins from memory. Then had a tour on the fiord, lunch and debrief before making our way home.

If you went deeper by x metres, or stayed longer than x mins, we refused to drive you back and you were forced to stay overnight or take a very expensive taxi ride home. This was explained upfront and I think in the 10 years that they had run this operation it had happened twice.

 

[Thalassamania]

There is another solution to overnighting or the taxi ride: surface (or even better at 3m): oxygen. Two hours of pure oxygen on the surface will take a diver from USN Repetitive Group N to USN Repetitive Group C (that is to say, "safe" to fly at 2,500m).

 

[boulderjohn]

One of the things that is very hard to calculate is the nature of the long ride to altitude. In many cases it can look like a staged decompression profile. The famed ride over Raton Pass from Santa Rosa, NM, is like that. There is an initial climb to altitude that most people do not realize is happening right out of Santa Rosa, followed by several hours at the same altitude, followed by the climb over Raton Pass. So it starts with a moderate ascent that should be within reasonable limits, several hours of no ascent, and then another ascent within reasonable limits. I have no idea how to calculate that.

Thal, I did something similar when diving in your area. I visited the volcano the day after diving in Kona. Going around the north end of the island yields a similar profile. An employee at the dive shop I used in Kona was quite insistent that I not go to the volcano until a full 24 hours after my dive, but I braved it anyway.

 

[Thalassamania]

One of the things that is very hard to calculate is the nature of the long ride to altitude. In many cases it can look like a staged decompression profile. The famed ride over Raton Pass from Santa Rosa, NM, is like that. There is an initial climb to altitude that most people do not realize is happening right out of Santa Rosa, followed by several hours at the same altitude, followed by the climb over Raton Pass. So it starts with a moderate ascent that should be within reasonable limits, several hours of no ascent, and then another ascent within reasonable limits. I have no idea how to calculate that.

Thal, I did something similar when diving in your area. I visited the volcano the day after diving in Kona. Going around the north end of the island yields a similar profile. An employee at the dive shop I used in Kona was quite insistent that I not go to the volcano until a full 24 hours after my dive, but I braved it anyway.

If you take the old UHMS recommendation that was likely in effect back then, you would wait 24 hours before going above (at the time) 500 feet, for any diving at all ... an hour at 30 feet, or 10 minutes at 130. Clearly that was a cover your ass recommendation, since even with a fully saturated 10 minute compartment, you'd be clear in 6 half-times, that is say one hour rather than a whole day. But we knew far less back then.

If I read my map right you are actually better to head south through K'au, you get a hair above 1,500 and then start the climb from Pahala to Volcano. If you to north through Wiamea you're at 2,500 feet when you hit Wiamea.

I can't tell you how many knuckle-biting flights I ade back from the Channel Islands to Freedom (if we were really tired and fizzy) or Fremont (normal base), struggling to hold the plane at 500 feet, sometimes in the dark ... the current 2,000 would have made life much easier.