Tahoe-High Altitude Diving

[grassyknoll]

I'm a recently certified diver, I had dived (uncertified) previously but thought it was time to get legit. My main prompting was an ucoming trip to Cozumel in October. Between now and then I am trying to cram in as many dives as possible. On eof the problems is that I live in the Sacramento Ca area and there just isn't that much locally. Oh yes, there are local dive shops but at this point I don't have the time or $ to head to the coast, which leaves pretty much lake diving. There are a few decent local lakes but nothing of too much interest. This weekend I decided I would try out Lake Tahoe. Being that neither my dive buddy or I had high altitude experience we went with a very conservative dive profile. I am definitely looking at going back soon, 100' vis, needed only 3mm gear and enough to look at to keep things interesting. We pulled some trash out with us and I found a fairly nice Seiko titanium watch (yay, found my first teasure).

I am looking for any good advice on high altitude diving, I will certify for this in the future but not until next spring when calsses are once again available. I've studied the adjustment tables and know some of the basics, I'm looking more for any personal experiences or observations you would like to share. I am also looking to buddy up with anyone that does or want to do Tahoe.

 

[altitudemike]

First you need to be at your site approx 6 hrs before you dive. You need to know your theoretical depth vs actual depth & you rate of ascent must be a lot slower than a normal dive at sea level. add 3 ft per 1000 ft above sea level for your theoretical depth. your last 14 ft try to take 30 to 45 seconds to ascend to surface. You really should get altitude certification first but if you're going to do it anyway these tips will help.

 

[grassyknoll]

I would never question the info fabout altitude diving rom someone with the name altitudemike, but perhaps you can clue me in to what I did or did not do correctly. I went from my home of 1500' to Lake Tahoe at 6225'. The adjustment tables I used stated that a 6 hour wait is necessary only at +8000'. Since my return trip would take me over a mountain range over 9000' I did overnight at the lake (24 hrs). I used an adjusted depth of 52' for my 40' dive (adjusting up to 7000' on the tables). I also began my dive with an assumed PG of N based on increasing 2 PG per 1000' (adding 2 pg to equal 7000' altitude). I could find no info on decomp so we held 10 minutes at 15".
Based on the above do you have any input? And yes, I will get my altitude certification when possible.

Thanks.

 

[altitudemike]

Sounds like you really did your homework first. If I had know your altitudes before I could have been more specific but based off the info you gave in your first post I just gave you a very safe dive profile. You biggest issue you tackle when getting altitude certified is actual vs theoretical depth & your rate of ascent. Your safety stop also should be at your theoretical depth so 11 or 12 ft. With all your homework on tables & using a very conservitave PG you were very safe. How did you like it. I'm landlocked so 95% of my diving is in mountain lakes between 3500 & 9000 ft. I love diving in the mountains.

 

[alo100]

3mm gear for Tahoe... is that enough? Oh, I never dive there, just I notice that even during summer the water is freezing there, am I right?

I swam there for 5 min or so, then the joints at my toes became painful..., the main reason why I left water....

 

[bolantej]

if you're wearing only 3mm in Tahoe, then I gotta make a trip out there soon. Last time I got there it was about 49 degrees F and I was wearing a 7mm plus a 6mm vested hood. Just make sure you don't leave to early after your last dive. Also, be careful, as it increases in depth quite a bit in some areas. I did a night dive in Meeks Bay. Great for crawdad hunting if you're into that.

 

[grassyknoll]

altitudemike-I usually prefer warm water diving but I had a blast. Some may say the lake is a boring as there is not much life to look at, but the vis was incredible and it was just a real mellow fun dive. Ther were tons of crayfish/crawdads that me and my buddy would collect and then drop onto eachother from above when not looking. Also found some large schools of fry (don't know what kind of fish though). All in all a good dive considering I can get there ina about an hour from where I live.

alo100/bolantej-I wore a 3mm 1 peice suit, 3mm boots and 5mm hood and gloves. My buddy was in full 7mm and he was dying, he used about 1/3 more air than I. There may be other thermoclines that would have made this uncomfortable for me had we gone below 40' (does anyone know roughly what to expect in Tahoe as far as thermoclines?).

We tries to carry as much garbage out with us as we coul (next time I'll take a bag) but one thing we left was a towel. At about 30' feet we see this towel laying on the bottom all spread out like someone was going to lay on it. The towel was from Hard Rock Cafe Chicago, the irony is that here is this garbage on the bottom of one of the most pristine lakes and it reads "Saving the World", classic, wish I had my camera with me.

 

[altitudemike]

I have always found the thermoclines in mountain lakes up here brutal so I dive my drysuit with my ice dive gear most of the time. I have only about 2 month of the year I can use my 7mm wetsuit.

 

[rocketry]

I think the altitude diving course is a must, but besides that a conservative dive profile would be best. Do you use a computer? Many have altitude adjustments. The Suunto Mosquito has 2 settings, a personal conservatisim setting and an altitude setting. You altitutde to its highest (A2) and the personal conservativism to its most conservative (P2). That would work...but no computer is a substitute for good planning and training.

 

[grassyknoll]

rocketry-Currently no computer, perhaps if I had one I would not have been so conservative in my dive profile. Technology sure is a double-edged sword, I wonder if sometimes it encourages some to operate at or beyond their limits and at points where the margin for error is precariously thin (please don't flame, I will be getting a computer and this is not a debate on it's merits, simply stating the obvious). Otherwise yes, I know nothing I learn on this board is a substitue for proper training.
As for certification, my OW class sure did open my eyes, I can't beleive how many classmates finished certifying on the same day that they panicked and made emergency ascents or panicked during mask removal/clearing excercises. I really hope some of those people I observed get dissilusioned with diving and never go in again rather than ending up a stat on the DAN site.:11: