How to Find Where You Are from the Sun: the basic principle.

David Ryan

David Ryan is a boat builder and USCG licensed master captain. He is the owner of Sailing Montauk and skipper of Montauk''s charter sailing catamaran MON TIKI You can follow him on Twitter @CaptDavidRyan

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13 Responses

  1. BlaiseP says:

    The ideal gift for an amateur astronomer (or the guy who has everything, including a seagoing vessel and a sextant) is the Nautical Almanac.

    I was consulting for a rather secretive executive placement firm. The CFO found me working late at night and advised me to double or triple my billing rate, though he wouldn’t do it for appearances’ sake and ethical reasons. Said clients wouldn’t take me seriously if I didn’t. Quite a guy. We became friends thereafter. Found out he was both an amateur astronomer and a sailor. So I gave him the next year’s Nautical Almanac as a Christmas present: it was then a simple matter of walking over to the book store in the Dirksen Federal Building in Chicago.

    In return, he gave me a hand-built 8″ Dobsonian mount telescope.

    I’ve always had a fascination for time and timepieces. There was once a magnificent collection in Rockford, Illinois, including a reproduction Harrison H-1 Clock, the first seagoing clock for the measurement of longitude. Captain Cook took a Harrison clock on his voyage.Report

    • Adam M in reply to BlaiseP says:

      Have you ever been to the Royal Observatory at Greenwich? They have H1 – H4 there, but I don’t recall which ones were actually working when I visited back in 2010Report

      • BlaiseP in reply to Adam M says:

        I have been to the Royal Observatory as a little boy. There’s a picture of me somewhere with one foot on each side of the meridian line. I remember the clocks but they didn’t register as very significant until much later in life.Report

  2. Chris says:

    I’m not from the sun at all.Report

  3. DRS says:

    David, did you ever read Dava Sobel’s Longitude, about the competition to find the best way to determine longitude? It was a most excellent read, and shows how recent was the discovery.Report

  4. Burt Likko says:

    I’ve always thought solar navigation was one of the most ingenious and clever things humans have created.

    I’m also struck by how much your sextant looks like a slide rule.Report

  5. Jack says:

    You are right that you never know. Few years back, admittedly before the proliferation of GPS (but well after beacon based and other electronic navigation had become ubiquitous) my navy frigate experienced a boiler explosion, leaving us without power or communications of any electronic sort. For two days we monitored our drift via solar and celestial navigation only. Didn’t exactly solve our larger problem, but it gave us sufficient warning should we need to drop anchor if we neared shoal water.Report

    • David Ryan in reply to Jack says:

      Just in the last week or so we had a mishap with one of the local long-liners. She lost all power and had no navs or comms.

      Fired off her EPIRB and the Coast Guard couldn’t find her.

      Finally she came within cellphone range and was able to make contact. Nothing damaged, no one hurt or killed.

      I don’t think a sextant would have helped them, but it goes to show, shit does happen, and sooner or later it will happen to you.Report

  6. Jack says:

    Haha yeah. When we had our unpleasantness, it was only some very imaginative Electronic Technicians that managed to take the batteries from our laser ring gyro and rig them up to the MARS station (essentially, a ham radio) long enough to get hold of a civilian that lived near a Navy base, and have them deliver a hand written note to the security guards informing them of our, er, status. Then add the humiliation of having a Coast Guard cutter come and take our big bad warship under tow.Report

  7. Ken says:

    In the longitude calculation, you should apply the equation of time. Without it your result could be off by as much as 16 minutes of clock time, or nearly four degrees.Report

  8. Tel says:

    Did anyone hear about the woman who went to a camping shop and asked to buy a sextant?

    The man behind the counter said, “Madam, we will sell you a tent, and what you do in it is your business.”Report