We're on day three at the Puerto Los Gatos (The Cats) anchorage waiting for the winds to die down before we proceed northward. Tucked in behind a prominent point of land and protected from the north winds, we can peer out into the open water and be thankful we have a place to hide. The whitecaps look intimidating out there.
While we wait I thought I'd practice some celestial navigation and take a few noon sights with my sextant. The sun lifts itself from the horizon every morning and settles back down again every night. Somewhere in between those events, it passes the meridian, a point where it's at its maximum point above the horizon. It's the actual time of noon for that point on the planet. The time of the meridian tells you your longitude and the height at the meridian can tell you your latitude.
I used tables in the Nautical Almanac to predict the time of the meridian passage (12:38), then used my sextant to observe that the height of the sun above the horizon slowly increased before 12:38 and then decreased thereafter. I used the height measured at exactly 12:38 to calculate (with more tables and some arithmetic) our latitude: 25 deg 13' N. The GPS says our actual latitude is 25 deg 18' N, a difference of 5 minutes or about 5 miles. I'm happy with that, especially considering my horizon is actually a distant shoreline. Five miles is close enough to find an island in the Pacific if we lose our GPS. Next up: sighting stars and planets.
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Congratulations on the noon sight, Rod. 5 miles is definitely close enough. Standing on land at sea level, your horizon is about 5 miles away, so an island should poke above that, plus you're on an elevated deck.
ReplyDeleteSorry to hear about the continued travails on the watermaker. Fussy thing, isn't it? :/