Advice ASAP Please

[Narcosis1]

I am moving to Spain in January!!

I will be joining a dive school on the south coast, after a day at work will I be safe to drive to my home town 20kilometers away in the mountain 1500 feet above sea level??

I know about altitudes etc, but what is the safe limit and height one can ascend to after diving!! Its normally advisable to leave 12-24 hours etc

Can some one also help us with advising me on Altitude diving as there are some great lakes to dive up here, what are the penalties on time and pressure etc.

 

[Norm]

All I can tell you off the top of my head is ascent rates are much more critical and safety/deco stops are pulled MUCH shallower. PLEASE read-up on altitude diving before you go. A good dive computer that compensates for altitude will prove invaluable.
Norm

 

[Rick Murchison]

1500 feet is not a huge adjustment. 1500 meters.. well, 1500 meters is another matter entirely. In a nutshell, decompression is figured based on pressure ratios rather than absolutes (psi), so you have to adjust your tables to reflect the new ratios. To give you an extreme example, were you to find a lake at 18,000', where the atmospheric pressure is half what it is at sea level, and you wanted to make a dive to 30', you'd need to double that on the tables to figure out your NDL etc.. in other words, you'd have to treat the dive as though it were to 60'. And you'd make your 15' safety stop at 7.5'...
The easiest way to approach altitude diving is to get an altitude compensating computer. Barring that, there are altitude adjusted tables available (I'm sure someone on this board knows just exactly where to get them). Using rough numbers (don't dive with these - get the computer or the table) you'll find that the adjustment for 1500' is approximately 10%.. ie add 10% to your actual depth to use the standard air tables. (if you want to make a dive to 50 feet, consider that the dive is to 55 feet on the tables)
Rick

 

[Rick Murchison]

Oh, my... sorry Narcosis... I answered the wrong question. You're not *diving* at 1500 feet, you're *driving* to 1500' after diving at sea level.
I wouldn't think that 1500' would be that terribly bad - the pressure differential in the first 1500' of air is equivalent to a tad less than two feet of water pressure. And since you're driving over 20K it'll take a while to get there.. Personally, I'd probably wait 6 hours or so, or make my last dive very conservative.
All of the "flying after diving" numbers assume a rapid ascent from sea level to 8,000' cabin altitude, by the way.
Let's see what Dr. Deco has to say..
Rick

 

[Narcosis1]

I'll have to check its not 1500 metres and not feet, otherwise its going to be a long day before I can get home.

I think my Aladin has altitude settings, will read up on it, as I never had to use them, also I always ascend at 10 metres a minute and slower so that side should be ok.

Why is Spain so bloody mountainous!!!!!

 

[Dr Deco]

Narcosis:

The advice the others gave earlier to you concerning slow ascents is always good to follow. As a rule of thumb, for every 1,000 feet of elevation, the pressure drops by the equivalent of 1 foot of seawater. As you can see from this, an ascent from sea level to 1,500 feet is small and to 1,500 meter is about five fsw. This is not really a disturbing amount to me.

However, I will assume that in this dive school you will be making shallow dives to learn welding, photography, etc. The story is quite different if you had just finished a dive with a long decompression (say, 200 feet with a 120 minute bottom time) or you just finished a training session involving a sat dive. This increase in altitude may not be without some risk.:boom:

This is, of course, assuming that you do not have DCS. This is possible in dive school where the profiles used are more excessive than ordinary scuba, eg, decompression is involved. People do have an exacerbation of their DCS problems when traveling over mountain passes of about 3,000 foot elevation.

As also mention, diving at altitude is different that traveling to altitude. In the former, the pressure changes on you body are instantaneous, whereas in the latter case, you have a period to off gas.

Last, why is Spain so mountainous? Because it is on the boarder of the African and Eurasian tectonic plate. These especially are responsible for the Pyrenees and Alps.

 

[Mario S Caner]

Dr Deco,
You sure got a good laugh out of me. I'll be sure to be careful when throwing questions your way. LOL

Mario