Getting bent on Haleakala

[H2ODoc]

...

But you are right, people have been diving in Santa Rosa, NM, driven back to Colorado and gotten bent after the trip. I know one very well--he did the same profiles I did for three days. I felt great. He was bent--seriously.

Curious - are you generally more fit than him? Anything else you might attribute his bent-ness and your un-bent-ness to? Dehydration? Just wondering.

My buddy that we'll be doing the diving/biking with is the picture of fitness. 5 mile run every other day. 15-25 mile Mtn Biking the other days. Me? I can knock down a 100 mile road bike ride without much pain, but I'm carrying a few extra (20) lbs, and not quite as lean and mean as him.

 

[LeadTurn_SD]

One way to reduce the surface interval need before going to work at altitude would be to dive every dive on Nitrox. If the dive is deep enough (and if ANDI certified or advanced Nitrox certified) you could ascend from the last dive on a rich mix to accellerate decompression.

Also please note that the U.S. Navy Table 9-6 is based on the U.S. Navy diving tables. Therfore you should follow the Navy table to plan your dive if you want to use the ascent to altitude table 9-6.

This might be a good question for the NEDU forum to see how the table was intended to be used and what it's limitations are.

Thanks for adding that, muddiver, I forgot to mention that Table 9-6 is to be used in conjunction with the Navy tables, not for example the PADI RDP, and you do need to read the directions for using 9-6 correctly.

Many recreational dives are multi-level reef dives, and Table 9-6 assumes a square profile. Using just a "square" max depth and bottom time to obtain a Repetitive Group in the Navy tables when the dive was actually a multi-level dive will probably add some conservatism; and since the tables are "air" tables, diving Nitrox would also add a safety buffer.

But, as with anything dealing with deco.... when in doubt, err on the side of caution and give yourself plenty of SIT before jumping in the car and driving to altitude.

Best wishes.

 

[boulderjohn]

Curious - are you generally more fit than him? Anything else you might attribute his bent-ness and your un-bent-ness to? Dehydration? Just wondering.

My buddy that we'll be doing the diving/biking with is the picture of fitness. 5 mile run every other day. 15-25 mile Mtn Biking the other days. Me? I can knock down a 100 mile road bike ride without much pain, but I'm carrying a few extra (20) lbs, and not quite as lean and mean as him.

I would say our fitness levels are similar. Believe me, we have talked about it and can't account for the difference, EXCEPT that once we got back to Boulder, I went to my home in the city and he went to his home in the mountains (nearly 3,000 feet higher).

 

[boulderjohn]

But, as with anything dealing with deco.... when in doubt, err on the side of caution and give yourself plenty of SIT before jumping in the car and driving to altitude.

There is so much that is unknown.

I finished diving one day in Kona and mentioned that I was planning to go to the volcano the next day, and the person I mentioned it to in the shop tried to talk me out of it. I took the northern route around the island, and I figured it was like a staged deco profile. There was an immediate climb followed by by a long stay at that altitude, follewed by another climb. It took me hours to get to Hilo (I should have dropped by, but hey) and so by the time we did the real climb to the volcano, I figured I was OK. I didn't have any problems, so I guess I was right.

My point is that no one really knows right now. We are all part of a grand experiment.

 

[LeadTurn_SD]

Hi John,

Yes, you should have dropped by (Just kidding, "Scuba-Guilt" mode now off).

Actually, I should have played hookey from work & family and met up with you to dive on the Kona side

Anyway, a few years ago I did some boat dives (rare for me, I usually shore dive) with one of the large operations in Kona. On the boat, I mentioned I would be driving back to Hilo that evening (these were morning dives, there would be about a 6-hour SI before beginning the drive home to Hilo) and the DM was emphatic that this was a terrible idea! But the boat captain overheard us and pulled me aside a few minutes later and said it was just fine.... And the DM overheard the conversation and in turn pulled me aside again a few minutes later and said don't do it!

I did not mention that I'd been doing the exact same thing since the 1970's because I apprecitated the DM's concern for my safety, and the DM was right, there is always a risk, even if it is a small one.

Best wishes.

 

[acooper]

I'm just guessing/estimating, based on the values for G and H groups, for 10,000 feet, which are 17:27 and 19:18 respectively. The SIT jumps considerably for each 1,000 feet of altitude, and does not appear to be linear.

The tables would not be linear. Unlike water pressure, which is roughly linear, atmospheric pressure is not, the equation is an exponential. The last few thousand feet up the mountain sees a lot of pressure drop. There is only 60% of sea level pressure at the summit of Mauna Kea, about 620mbar.

 

[acooper]

I did not mention that I'd been doing the exact same thing since the 1970's because I apprecitated the DM's concern for my safety, and the DM was right, there is always a risk, even if it is a small one.

It really is an issue here on the Big Island, where so many places are well above sea level and elevation gain is easy on the way home. In our regular dive group we have a number of folks who call Waimea home, at 2,500ft elevation. My wife and I have a house at 1,000ft elevation. Our usual answer is to have lunch somewhere at sea level after the morning dives, kill a couple hours before driving home.

 

[augk]

Wow ride 12 MI up hill. I drove up but wasn't diving at the time but it was an interesting lesson on gas expansion. It was a nice ride when all of the sudden something goes pop. My first thought was one of the tires on the car I stopped took a look nothing, proceeded cautiously to the top waiting to see what might go wrong. At the top I gave the car another once over and found nothing thought maybe just a rock. So the misses and I scamper off to explore the sights see the crater and all there is to see. We had packed a brown bag lunch with sandwiches and snacks and drinks so when we decided to have our little volcano top picnic. Low and behold I discovered the source of the pop all of the food containers were expanded like balloons with the exception of the bag of chips which burst open. LOL

 

[Lopaka]

Our usual answer is to have lunch somewhere at sea level after the morning dives, kill a couple hours before driving home.

Good answer for most........ But then, I did much the same and starting having double vision and assorted weirdness after dinner at Daniel Thiebaut's at least 4-5 hours after diving. Vanished when taking the fast way back down to sea level. Duh....what might that have been all about?

Then again, I did have a PFO (fixed now) and my wife had no issues after the same dives. Some of us are more prone to this stuff, so one size fits all is not good enough. Just being a devil's advocate here about driving to altitude.................

 

[friscuba]

A problem in my life, but one I do think about. I work a couple days a week at 13,600ft. Weekend dive? Going to the summit on Monday? None of the standard references I have found address this extreme. How long does it take to flush the N? Is 24hrs enough? I have done a dive on Sunday morning and gone to the summit on Monday without problem, but it is generally something I avoid doing.

Hi Andrew. I'm pretty sure I had a couple of telescope guys on the boat maybe two or three years ago, can't remember who they worked for, that said their rules were to stay downhill for a certain amount of time. It was longer than 24 hours from what I recall, but I can't remember how much longer. For some reason the numbers 29 and 37 pop into my head (that's a pretty big range). Unfortunately the NOAA tables only go to 10K elevation. Sounds like the longer the better anyways.