NavList:

This is a once in a lifetime chance for most amateur sailors. Don't waste it on "ordinary" sextant shots.

There is enough info on line to construct a Mercator chart of your wider area, combining lat/long numeration with 2nd and 3rd contact times scales in GMT.

Make sure you grab a place where you can squat and see the sun, without sails blocking the view. Have at hand a way of reading GMT in daylight and darkness, and to note it down, eg backlit 24hr format watch, lit clipboard, ball pen, eye-glasses, piece of welder's mask screen.

It is easy to see the gradual approach of totality, but the change from normal light to total darkness (2nd contact) is almost instantaneous. Note the time! Same with the reappearance of the Sun (3rd contact.) It's a flash.

Use the period of totality to look around! Observe the symmetry of the aurora, any nearby planets, and maybe the all round horizon brightness. Enjoy!

The timing of 2nd and 3rd contacts gives instantaneous dynamic longitude on your chart.  If the aurora wasn't symmetrical, you're not quite on the eclipse path, and may have to do a sextant sight to get lat. 

I once planned to do this in my boat, but with cloud inevitably forecast, switched to an open biplane. Perfect view. Real lunars without a sextant. Enjoy!