Diving in high mountain lakes??

[The_DivePirate]

If a students OW dives are being done at altitude, then the instructor should cover it.

It sounds too me that Castle lake does not have easy enough access too take an OW class there for the check out dives. The OP said that he wanted too dive that lake in a year. If the class is done at sea level or below 1000' there would be no reason for teaching altitude theories, unless a student request it because of their diving intent. When I teach a class in Hoods Port, Washington through the shop I dont bring up anything about altitude diving, why fill the students heads with even more info, they have plenty too digest and don't need anything else too cloud their minds. Now at home here in Central Oregon I do touch a little on the effects of altitude on the body, our check out dives are done at either 5000' or 3000', so I figure if they live here in the area they should at least have a thought in the back of there minds about the issues of altitude diving.
One other thing that needs too be addressed here is, usually when you are diving at altitude, you are a long distance from any help. (EMT's and such) So, if you do run into problems, you may not be able too contact or get to help before it is too late. So why not help your chances and get a course that helps greaten your odds for success rather than set yourself up for failure?

Joe

 

[JeffG]

Right, they should. Show me where the OP mentioned he would be certifying at altitude, his goal is to dive the lake sometime in the future.

My bad.


I misread it.

Oh well....in that case I would just ignore the altitude.

 

[nwbobber]

I don't think its necessary to take a class to learn how to do an altitude dive. The difference in atmospheric pressure can not be ignored, however. Basically 1 psi atmospheric is going to equal 2.306 ft freshwater, or 2.244 ft saltwater. You can do your own conversions. When you ascend the final pressure at the surface will be less than sea level, so at a given atmospheric pressure you will treat 1 atmosphere in depth as you would 33 fsw at sea level. I did a search for atmospheric pressure at altitude and found this: Air Pressure and Altitude above Sea Level

2500 ft is 13.41 atmospheric, so 13.41 * 2.306 gives you 30.906 ft is one atmosphere. Another way to figure it would be to divide 13.41/14.7 which gives you .912 If you are going to dive with tables correct depths by multiplying the depth on your table by this number. You also need to modify your ascent rate by the same amount. At sea level you ascend at 30 fpm maximum. At 2500 ft 30*.912 gives you 27.36 fpm max.

If you have a computer there should be instructions on how to set it up for an altitude dive. At 2500 ft this all is not too much of a concern, but it IS something that you should be aware of.

Another consideration is after the dive, when you have elevated levels of nitrogen in you tissues. The hike out of castle lake would be considered strenuous physical activity. This is not recommended soon after diving. It's kind of like shaking a bottle of pop. It would be best if you planned a good surface interval into the trip before your hike out. A couple of hours maybe. The fishing's good. Enjoy.

 

[nwbobber]

I'm sorry that ascent rate would be 30 fpm at sea level and 30*.912 , 27.36 at 2500 ft.