Lee,
If I was marooned on a desert island with Evangeline Lilly and no one else, I wouldn't be in a hurry to tell her I knew where we were from the Sun, the stars and a watch. I am not that stupid.
I can definitely relate to this. In these circumstances I would contract instant amnesia and forget all that you have posted about navigation and might be tempted to dump the watch just in case my memory returned.
Lilly would be a useful lookout on your island as she has always been a bit of a tomboy. Indeed in several episodes of Lost she was filmed climbing easily up and down trees and for a time was nicknamed 'MonkeyGirl' on set.
If Evey is reading this we would welcome her views on weighing bins, Leica's latest and navigation.....
Lee