great lakes navigation
 

No. I don't buy that. The "height above water" correction is to bring the horizon up to
the height of the observer. The horizon (assuming you're no so high the you're seeing
land) will need exactly the same correction whether you're 10 feet above sea level or 10
feet above lake level. Unless the lake is "tilted" the horizon is approximately level.

Now I can believe that there's some minor correction needed for lake level that I don't
know about, and I'd be curious if you knew why such a correction is needed, but it clearly
isn't a simple "height of observer" correction.




"Jim D." wrote in message
. com...
Jeff,
You have to correct to sea level. Not the level of the lake. Lake
Michigan is (or was when I was doing my navigation class, I believe it is a
couple of feet lower now) 579 feet above sea level. You need to add that to
your height off the water to due your calcs.
Hope this helps.

Jim D.