Avoiding suicide

[Inspector#2]

Need some help from the gurus. I want to dive a lake at 12,600' with a 48 hour surface interval prior. Been at 6000' for 3-4 days prior and around 11,000' for the last 18-24 hours. 30' actual for 20 minute bottom time. No deco, 21% O2, no fancy stuff just a straight forward single dive. Ran the scenerio on VPlanner and it looked like this.

Dec to 30ft (0) on Air, 50ft/min decent.
Level 30ft 19:24 (20) on Air, 0.32 ppO2, 17ft END
Asc to sfc. (21) on Air, -30ft/min ascent.



Does this sound OK?

Dave

[roakey]

I usually just use the Navy tables at altitude. A rise from 11k to 13k will mean 4 pressure groups. Even rouding up to say you're at .5 ATA which would make a 30' dive 60' adjusted for altitude, going in as a D diver to 60' I think* would easily allow a 20 minute dive.

* I don't have my Navy tables in front of me, verify this.

Roak

[Uncle Pug]

I2... you are going to add a data point to the theoretical modeling of V-planner?

Well... since you are going to donate your body as a *deco goat* will you have someone on hand to document the exposure and results?

Any chance of doing this as a progressive experiment... shallower~n~shorter adding depth and time on subsequent dives after a sufficient interval of say... 24hrs?

btw: what is the reason for the dive other than to advance the body of knowledge in altitude diving.

[Inspector#2]

Beautiful high mountain lake with a possibility of ore bearing rock in it. I don't think I will go to the full 30' but an outcropping of rock is just below the surface that I wanted to check out. As clear as the water is I wasn't sure how deep the rock goes but my limit was 30' @ 20 min.
The parking lot with camp site is at 6000'. "Base camp" is just below the lake at 11,000'. Probably overnight there and dive after noon then another overnight before leaving down to the cars.
The time to do this is gone for this year and the lake will be frozen in a month, just an idea for next August.

Dave the goat.

[Uncle Pug]

...but of course if the dive is successful you will have to dispose of them after they pack your stuff back out.

Dr. Deco would tell you that exercise before or after a dive is not a good idea... bubble seed generation.

[Rick Murchison]

At 12.6K you'll be at approximately .6 ATM. I think 48 hrs is sufficient to consider you've offgassed... so...***corrected copy*** Since your SI is at a lower altitude you'll be starting as a group "D" as Roakey sez...
for your lake, 1ATA=.6*34FFW=20FFW; Your 30FFW dive puts you at 2.5ATM, an equivalent depth of 50 FFW.
Your ascent rate should be 20 vice 30 FPM, and your safety stop should be at 10 vice 15 feet.
20 minutes is 20 minutes; plus the 29 minute penalty from starting as a "D" diver - at the end of the dive you'll be a "G" diver.
In round numbers.
However...
WARNING
Diving at altitudes above 10,000 feet imposes serious stress on the body and is strongly discouraged. (NOAA Diving Manual)
Rick

[roakey]

Rick,

He's going to rise 2k before he dives, that's four pressure groups even before he hits the water. He starts as a "D" diver.

Roak

[Rick Murchison]

roakey once bubbled...
Rick,

He's going to rise 2k before he dives, that's four pressure groups even before he hits the water. He starts as a "D" diver.

Roak
You're right - I locked onto the 48 hour SI and didn't read on to the details. Even worse... still within the tables, exiting as a group "G"... but there's still that pesky WARNING!
In fact, just so there's no doubt, and I don't run the risk of having posted a bad plan, I'm gonna go back and edit it - thanks for the catch.
Rick

[roakey]

Scubaturek and I have been eyeing a very high altitude lake here in Colorado. We've already decided that if we do it it'll be on a real hot Nitrox mix like 50% or better just to make the N2 loading as minimal as possible.

Roak

[Inspector#2]

Roakey,
When are you planning on doing your dive? I would love to know afterward what you would have done different, better, etc.

Thanks for all the help here, my lungs and brain really appeciate it!


Dave

[roakey]

The mountains got at least six inches of snow over the last two days, so it's a pass until at least next year...

Roak

[Divesherpa]

Did someone say they needed sherpas?
I'm a hell of a tank toter and my resume grows several times a week.:)

[Uncle Pug]

Divesherpa once bubbled...
Did someone say they needed sherpas?

But if the mission is successful your resume growth ends.

[Divesherpa]

Hey, wait a minute..

I don't think I'll sign up for that one. Back to the jungle for more bugs, snakes, and crystal clear warm water at an altitude that is very boring.

I miss mountains, but that's another story.

[omar]

Get a copy of:

BASIC DIVING PHYSICS & APPLICATIONS
Bruce R. Wienke

He goes over altitude diving in a very thorough manner. He also is a diver in New Mexico and has some experience with this as well. In addition, it is a very good reference for more advanced diving topics.

[scubaturek]

Since roakey spoke my (screen) name, I'll put in my 2 cents. Living in CO like we do, all our local (including NM) diving is at altitude. We regularly dive at 10,000'. We normally use simple tables (navy, PADI) to figure out what we're doing. I2, I really like v-planner, and while I've never implemented it (only a matter of time), I think it's logical.

Rick, roakey and I ice dive at a 10,000' lake each winter. 20-30' for 30 minutes. No sweat. Really, absolutely no sweat, at all! Now, we are no spring chickens, and adding these RISK factors together is rather imposing, but, if I may quote Dave Sutton, we don't *take* risks, we *manage* risk.

I2, there are 2 lakes here that are close to 13,000' that are accessible. We'll have to work to get there, but we'll use drysuits and simple rigs, like maybe bp's and al40's for a dive to 20-25' for whatever. Next year. Hopefully. Gotta plan some more.

The Cross corrections for altitude stop at 10,000', but that doesn't mean diving gets radically risky beyond there. Lake Baikal, anyone?

Joe