1st Time Diving at Altitude - Questions

[Lopez116]

Hello SB'ers,

I have an opportunity to dive Lake Tahoe and have a few questions since this would be my first dive at altitude. I understand the avg elevation there is about 6,300 ft.

1. Other than making sure my computer (Suunto Zoop) knows I'm at elevation, is there anything else I need to do to compensate?

2. If I am driving up to the lake from SoCal, do I have to wait any period of time to acclimate to the elevation before starting to dive?

3. If I bring my own tanks (Al 80) from down here, is it ok to have them already filled up when I make the drive up? I.e any issues with gas compression/expansion in the cylinder?

Thanks in advance!

 

[Lorenzoid]

If there's a dive shop in the area, I'm certain they offer a course in Altitude Diving.

 

[DivemasterDennis]

1. While your computer will give you accurate ndl time if it adjusts for altitude, if it does not you need to adjust per "altitude tables. At 6300 feet that means calculating your ndl at about 20 to 25 % deeper than actual depth planned. For example, a dive to 50 feet should be calculated at 63 feet, a dive to 80 feet calculated as if to a depth of 101 feet.

2. No need to wait for a specified time to acclimate, other than move slower on the shore and take initial surface swims easy. Difference from lower elevation 02 will be compensated for once you are 8 to 10 feet deep and breathing air under pressure.

3. Not an issue at all in a closed aluminum cylinder. Water temperature or air temperature , if different from that at the time of fill, will have the greatest impact, likely colder where you are headed, so get a good fill, as it will measure less after about a minute in cold water of Tahoe.

DivemasterDennis ( speaking with a lot of altitude diving experience)

 

[Bob DBF]

Find out if your computer adjusts to altitude! If it doesn't, make sure you know how to calculate for altitude as you can be a lot closer to NDL, especially if you drive up from the Sacramento valley and jump in the water.

2. No need to wait for a specified time to acclimate, other than move slower on the shore and take initial surface swims easy. Difference from lower elevation 02 will be compensated for once you are 8 to 10 feet deep and breathing air under pressure.

DivemasterDennis ( speaking with a lot of altitude diving experience)

Since DivemasterDennis already lives a mile up a trip to 6225' is nothing. For the rest of us from sea level, hauling gear around at that elevation can get you out of breath and if you don't know it can happen, it can be a shock. Acclimation can take a while, if you start getting winded stop and rest a while. His advice is spot on, take it easy and it all goes away while diving.


Where are you diving?


Bob
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A man's got to know his limitations.
Harry Callahan

 

[lindenbruce]

You will have fun. I have dove the California and Nevada side of Lake Tahoe several times. The viz should be great. You WILL feel the thermoclines that's for darned sure. Lots of crawdads and smaller fish. Here's a link for fast depth calculations. Run some numbers before you head up into the hills and write them down on your slate. 8th Element Diving - Scuba Math - Altitude Diving: Understanding the Tables B.

 

[Hawkwood]

Safety Stop is a bit shallower as well. At that altitude it would be 12 feet rather than 15 feet. We dive a altitude where I am from.

Both DivemasterDennis and Bob DBF have given you advice that is spot on.