Bill,

A minute is a nautical mile at the equator. At 30N, it's about 1/3 of a mile.

I think we can both agree finding true north using the north star is elementary. Lay a piece of 550 cord on the ground NS. Tie it so it's straight under tension.

Then hang another piece of 550 cord vertically at the South end of that line. When the shadow is aligned on the cord, that's local noon. It will only last for a few seconds. The longer the cord the better. No reason you can't use a 30 foot cord hung from a tree.

Now it's simply a matter of knowing offset from an assumed position. If I assume I'm at 90W and it arrives an hour later, I'm at 105W. Each degree is 4 minutes on the watch. It's quite hard to be off even a mile.

This can't be done without practice, and it's not necessary to know. It's just something I played with once.