Can I get bent going to 2000' after a dive at sea level?

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scubadiver888

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I just don't log dives
I was going through my dives on my dive computer when I noticed the computer was in LVL2 mode (altitude reading). I live approximately 500' above sea level.

How much would I be increasing my risk for DCS if I did a dive then came right home? What if I lived in the mountains? Could diving at sea level then going to 1000' add significant risk?

I've heard of people diving in the Pacific Ocean then driving to Calgary, Alberta and getting bent as they drove over the Rocky Mountains. Obviously, going from a dive at sea level to 10000' is just asking to get bent. What is most likely safe and what is definitely unsafe? 1000' is probably okay? but 5000' is bent?
 
It depends on your dive profile... but a 2000' change in elevation shouldn't get you bent unless you are in a VERY high pressure group upon surfacing, and immediately return to altitude.

Here's NOAA's Air Diving Table - http://www.ndc.noaa.gov/pdfs/NoDecoAirTable.pdf

and their required SI before returning to Altitude - http://www.ndc.noaa.gov/pdfs/AscentToAltitudeTable.pdf

The letter groups are not interchangeable with other dive tables. :wink:

Even still... nothing can guarantee that you won't get bent...
 
thanks for posting that it helped me out
 
It all depends on your nitrogen loading, how long your "SI" is before you start driving to altitude, hydration and so on and so forth..
 
I have a good friend that went from sea level to 2000 ft, within 12 hrs. He woke up the next day suffering from a hit. He did not fly, just drove, and the end altitude was the highest he had hit. Now, here is a bit on the dives- multiple day deco diving, depths of 110 average, accelerated stops. He also had a few beers on the way home....thereby dehydrating him. This happened about 10 years ago, if I run the same profiles, my computers give me a 26-30 plus hour no fly time. Not sure where that puts 2000 ft, but I personally wait at least 18 hrs before going that high.
-J
 
I have a good friend that went from sea level to 2000 ft, within 12 hrs. He woke up the next day suffering from a hit. He did not fly, just drove, and the end altitude was the highest he had hit. Now, here is a bit on the dives- multiple day deco diving, depths of 110 average, accelerated stops. He also had a few beers on the way home....thereby dehydrating him. This happened about 10 years ago, if I run the same profiles, my computers give me a 26-30 plus hour no fly time. Not sure where that puts 2000 ft, but I personally wait at least 18 hrs before going that high.
-J

The only way you are getting bent by climbing 2000 ft in elevation 12 hrs after a dive is if you were already bent after getting out of the water. Waiting 18 hrs instead of 12 hrs is kind of pointless. Just make sure to adequately decompress and you should be able to ascend to 2000 ft elevation 2 hrs after a dive. Fix the correct problem, which is the decompression, not how rapidly you go up 2000 ft.
 
Certainly is dependent on a number of factors. However, a few years ago we had an instructor get bent after what appeared to be a series of fairly conservative dives based on her computer. What do people think caused it? She drove across the island to see her boyfriend. Maximum elevation along the route she took was just over 1,600 ft.

I used to worry about my increase in elevation during the days I dragged all my SCUBA gear uphill to my house on my hand cart. The rise in elevation wasn't a lot, but the physical exertion was.
 
Thanks everyone, especially HowardE. From the documentation provided I think I'm fine but I could put myself at risk. I was deep diving (100' +) for three days and pushing the NDL each day. Fortunately, I took my time coming home so it was around 6 hours before ascending to the higher altitude.

I don't know how high my apartment is above sea level but I know it is 500' above ground level. If I lived in one of the skyscrapers in the north end of my city I can see being definitely 1000' above sea level. :shocked2:

I wouldn't have thought going home could get me bent. I wonder why PADI doesn't have something on this. NAUI obvious has THE answer not just enough data to figure it out. I'm a little disappointed with PADI's RDP for not providing a return to altitude chart.

Thanks again.
 
1,000 ft is 0.96 ata or 1.2 fsw above sealevel
2,500 ft is 0.91 ata or 2.8 fsw above sealevel

how long do you think you need to take of a decompression slide going that far in order to decompress?

for example, in a 60 minute compartment a 60 minute/60fsw recreational dive will give you one half time:

( 60 / 33 + 1 ) * 0.79 = 2.22636 ata ppN2
( 2.22636 - 0.79 ) / 2 + 0.79 = 1.50818 ata ppN2

after 1 hours: ( 0.79 - 1.50818 ) / 2 + 1.50818 = 1.14909 ata ppN2
after 2 hours: ( 0.79 - 1.14909 ) / 2 + 1.14909 = 0.96955 ata ppN2
after 3 hours: ( 0.79 - 0.96955 ) / 2 + 0.96955 = 0.87978 ata ppN2

so after 2 hours, you can ascend to 1,000 ft without having any driving pressure gradient in that compartment. after 3 hours, you can ascend to 2,500 ft without having any driving pressure gradient in that compartment. you can do a similar analysis with other compartments or other repetitive NDL profiles and you're not going to get enough loading some number of hours later to be driving any gradient at all at these kinds of altitudes (much less violating your M-values).

these people who, hours later, drive to a slight altitude and get bent were all bent to begin with. it isn't the dissolved phase overpressurization which is causing the symptoms in these cases, it is all the free-phase gas they've got from poor decompression. it doesn't matter how slowly you ascend to altitude in that case, you're still bent.
 
Well, Lamont may be right. Like I said, my buddy took his hit 10-12 years ago, and according to DAN and the treating physician, it was from going to altitude. Their words, not mine. DAN just was conducting a recent alt/dive study, write to them. There is a wealth of information available, all of us (unless someone here is a hyperbaric(sp) doctor) are only able to relay what we know of first hand.
-J
 
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