Just did my first Open Water dive at Pleasant!

[runamonk]

We had 2 instructors for about 12 people...my BUDDY let me down as far as im concerned, she was the one who was supposed to check my gear. But I agree, maybe my instructor should have went by everyone and checked them.

Sounds to me like you learned a lesson.

My wife and I learned a very very important one while on a fun dive with some friends. We got down to about 30 feet or so and my BC would not stay inflated, my inflator wasn't fully tightened down to my BC so air was leaking out of it as fast as I was filling it up.

 

[shark.byte.usa]

Divers with tables make altitude adjustments by planning their dive for a theoretical depth. Following is a link to a chart that was printed by Skin Diver Magazine that looks very similar to the one I use.

http://www.sandiasnorkel.com/info/inf-g_10.php

"The Altitude Chart appeared in Skin Diver magazine 1970 " :11: I found that interesting.

For you instructors, what's the general rule of driving to higher altitudes after diving? I generally like to grab a "last dive" in Socal in the morning just prior to driving home. Have I thought about the altitude change, YES, but the shops do it so I didn't think it was much of an issue, and it's hours before I start climbing to any real height. I know your not supposed to go to [much] higher altitudes, but what is the rule? I know in Maui they warn not to go up Haleakula (10,000') after diving, but that's a far cry from the 1200-1700' we get here in Phoenix, I'm sure it's gets a bit higher between SoCal and here. So what's the skinny???

-Garrett

 

[Dive-aholic]

Garrett, the problem with driving back from SoCal is we do drive through a mountain pass that's close to 7000 feet (if I remember right). This can be a real issue. The recommendation is to wait the 18 hours after multiday diving just like when flying. Yes, the shops do it, but the shops are thinking about the bottom line. The first time someone takes a hit driving over that pass they'll all stop doing it. Check out the Rocky Mountain forum. They've discussed the driving to altitude issue quite extensively since they're driving from Blue Hole, Santa Rosa through a high pass back to Denver area. Basically, very few studies have been done in regards to altitude diving so we have to be conservative.

 

[scubajcf]

Hi Garrett,

Yeah, the 1970 reference does knock you back a bit, but the good news is atmospheric pressure hasn't changed a whole since then. Also, I compared it to my AOW Diver Manual and the chart in there is identical (copyright 2001 - if that makes you feel more comfortable).

The problem with driving to altitude is there is not a whole lot of data and research unlike flying after diving. I would imagine (and this is just a guess) is that there are too many statistical anomolies and variables such as speed of ascent, grade of ascent, etc. that would make a study too difficult to control and reap any truism from it.

To be conservative, I would take the most cautious advice available (as Rob points out very appropriately) and use that as a reference. Coming from San Diego, you go over a pass that is around 5,000 feet above sea level about 90 minutes out of town. If you were diving Scripps Canyon or the Yukon just prior to that, you might increase your risk of Decompression Illness. I don't think there is as much of a radical incline coming from Los Angeles (I-10). But if nothing else you can assure that you are making at least a 2,000 foot ascent.

Rob mentioned the Rocky Mountain forum. When I lived in Denver, we used to go down to the Blue Hole regularly and we would all overnight there to avoid the pass, which is in excess of 7500 feet (memory fading fast). As for California, when we do Liveaboards in California, typically most people overnight in Riverside or Santa Barbara depending on the boat. As for San Diego, I would hangout and enjoy Ocean Beach, Mission Bay and/or Pacific Beach and off-gas before heading home.

I know when flying between islands in the Caribbean, I've taken sea planes and told the pilot to stay below 1000 feet and they had no issues whatsoever. In fact, I think they prefer that. Just remembering one flight flight where I don't think we went over 100 feet. Pretty cool!

Again, no guarantees you are going to take a hit as many folks have probably tested this driving from San Diego and walked away unscathed. I just don't want to be the unlucky one that proves altitude after diving don't mix.

jcf

 

[shark.byte.usa]

7000'???, Well we may be talking 2 different routes, I take I-10 all the way to and from OC. Along this route I thought Chiriaco Summit, CA. was the apex and according to google earth [I don't know how accurate it is] it's at 1700' [same as Pleasant] granted Indio at the foot of the climb is at sea level so it's a shot straight up. Now from what I can tell the I-8 route to and from SD spikes over 4500' through the pass just before you reach SD, so definitely not advisable I can see that, but < 2000', is that a great risk?? Like I said it's usually at least like 6 hrs before I reach Indio from the time I pop up out of the water. My computer usually reads no residual nitrogen by that time.

So it there a general guideline? Like, you shouldn't have an elevation changes in excess of 'X' amount of ft. after your last dive.

So you definitely shouldn't dive the Yukon or get any depth in LJ Canyon and drive I-8 home right after

-Garrett

 

[shark.byte.usa]

jcf,

I was typing didn't see your post, looks like we're on the same page


Interesting conversation, as I said I've thought about it but dismissed it pretty quickly, perhaps I should rethink the morning of departure dives altogether or just hang out a couple hours longer.

Garrett

 

[scubajcf]

< 2000', is that a great risk??

So it there a general guideline? Like, you shouldn't have an elevation changes in excess of 'X' amount of ft. after your last dive.

- Garrett

Whether or not going to 2000 feet is a risk is something you have to decide after you have gathered the appropriate training and information. Is there a guideline, yes there are several published guidelines. The one I reference is linked below. You would need to determine on your own (INSERT HEFTY DISCLAIMER HERE) whether or not it is right for you. Remember any elevation change MAY increase the susceptability to DCS. While guidelines and decompression models are based on extensive research, everyone's physiology is different, thus your susceptability to DCS is different. The only way to avoid DCS is to not dive (yeah right).

I think this will help answer your question(s);
http://www.diversalertnetwork.org/medical/faq/faq.asp?faqid=54

Hope this helps!

jcf

 

[Dive-aholic]

7000'???, Well we may be talking 2 different routes, I take I-10 all the way to and from OC. Along this route I thought Chiriaco Summit, CA. was the apex and according to google earth [I don't know how accurate it is] it's at 1700' [same as Pleasant] granted Indio at the foot of the climb is at sea level so it's a shot straight up. Now from what I can tell the I-8 route to and from SD spikes over 4500' through the pass just before you reach SD, so definitely not advisable I can see that, but < 2000', is that a great risk?? Like I said it's usually at least like 6 hrs before I reach Indio from the time I pop up out of the water. My computer usually reads no residual nitrogen by that time.

So it there a general guideline? Like, you shouldn't have an elevation changes in excess of 'X' amount of ft. after your last dive.

So you definitely shouldn't dive the Yukon or get any depth in LJ Canyon and drive I-8 home right after

-Garrett

It's been a few months since I've been to SD, so my elevation is off. I travel a lot and do remember a 7000' pass somewhere, but can't remember where now.

Like John said, a 1700' change in elevation is a personal choice. No one has done the studies necessary to show whether this is okay or not. It's definitely a risk, but how much of a risk is the question. I have driven to altitude after driving, but it's not something I like to do. I live at 3500' and have driven to Pleasant for a couple of dives and then home afterwards! Whenever I do it, I am very aware of the aches and pains I had before I start the drive and monitor them throughout the drive. I've been lucky so far.

Just do what's in your comfort zone, but be aware that it is a risk.

By the way, if anyone wants to learn more about the specifics and considerations of altitude diving, I will gladly tell you about it in person. Just come out to the lake when I'm there.

 

[scubajcf]

Whenever I do it, I am very aware of the aches and pains I had before I start the drive and monitor them throughout the drive. I've been lucky so far.

It sucks getting old, doesn't it? Right there with ya.

 

[glcoley]

An "Altitude Dive" is defined as any dive made at 300 meters/1000 feet or greater above sea level. Lake Pleasant is at about 1700 feet above Sea Level. Since (most) decompression models, dive tables and computers were developed for use at sea level, we need to modify our dive profiles to adapt to the changes in pressure as a result of our increase in atmosphere. Decompression models control the release of nitrogen absorbed during your dive by assuming you will begin and end you dive at sea level under a full atmosphere of pressure.

When you are away from the coast, like we are in Arizona, we have to accomodate for the increase in altitude where there's less air pressure. Thus Altitude Diving requires special table or computer procedures to account for the atmospheric pressure difference. While the decompression model difference is minimal at Lake Pleasant, it should not be ignored. Always follow the proper procedures, no matter how minimal the risk differential. Diving at altitude without following the proper altitude procedures increases the risk of decompression illness.

Without getting into the whole Altitude Diver Specialty Class:

Divers with computers make altitude adjustments by reviewing the owners manual. If their computer changes automatically, then no action is needed on their part. However, it has been my experience that computer altitude preferences need to be set. In the case of Suunto computers, they have an altitude setting of (A0, A1, A2, and A3). A0 is obviously sea level and A1-3 is a range setting. For Arizona, we use the A1 Setting which is calculated up to 3000 feet or 4000 feet (I don't exactly remember).

Divers with tables make altitude adjustments by planning their dive for a theoretical depth. Following is a link to a chart that was printed by Skin Diver Magazine that looks very similar to the one I use.

http://www.sandiasnorkel.com/info/inf-g_10.php

With this, you take your actual depth, convert it to a theoretical depth depending on your altitude, and plan your dive accordingly. Please note the difference for safety stops.

Lastly, there is a lot more covered in relation to Altitude Diving such as arriving and departing altitude, physiological effects and potential safety hazards, depth gauge and computer use, etc. If it is something you are planning to do (Lake Tahoe, Colorado, New Mexico, etc.), get the proper training. While Scuba Board is a great reference tool, it doesn't replace a Scuba Instructor.

JcF

PS - Remember your "flying after diving" rules (see back of tables). That applies to driving to altitude as well. It should properly read, "reaching altitude after diving" rules.

thanks for giving Sandia Snorkel & Scuba some ad exposure, my dive LDS in New Mexico,
I keep the altitude chart in my log book, laminated it in plastic and puched holes, now always handy when I need it, athough my computer does all the work now,
the dive guides are very serious about this in Lake Tahoe, as they should be, love diving there, but take the altitude certification class, nitrox and dry suit...
only way to go in Tahoe
have fun