Apparently the oldest known Mariner’s Astrolabe has been found!

Known as da Gama’s or Sodré’s astrolabe, it was found in the wreck of the Esmerelda, HERE.

The 3D photography indicated it had scribe marks for measuring the height of the sun, allowing the sailors to calculate their latitude.

This simple instrument was much less complicated than the ones used on land, because of ship movement, and these predate sextants by about 300 years.

When I was a navigator in the 80s and early 90s, we still did cel or celestial navigation as a backup to the inertial navigation systems on the airplane. We were happy to be within 5-10 miles of the actual position due to bouncing around and the time it took to take multiple measurements 2 minutes apart on different stars or the sun.

HERE is a nice article from Air and Space on a pilot’s use of a similar bubble sextant. With the advent of accurate clocks, good charts, The Nautical Almanac, and the training to plug and chug though the various pages, calculations, declination, etc. You could actually get close enough to home to get a TACAN lock on, where the early mariners were happy to get ‘close’ to what latitude they were on. I cannot imagine how frustrating that must have been to the navigators on those ships!!!



TBT… — 21 Comments

  1. Difficult, yet navigate they did. The risk of botched navigation is a concern to us today, but THEN in the era of da Gama (and others), it was far more than mere concern. I look at these discoveries of ancient instruments with a lot of humility. They set sail WITH THAT. Our reliance on technology is no guarantee – and as you point out, we return to the sextant and to basic navigation again and again. You were able to fly above the clouds to shoot stars or the Sun…but what of sailors who could not?

    There was a fortitude and a will then, that we have to find in ourselves from time to time and as with the innovative astrolabe, to overcome.

    • It wouldn’t be until the 18th century before John Harrison invented a chronometer accurate enough to make longitude determination fairly fast and convent. One wonders how those early navigator found room for their balls on those tiny ships.

    • I have read that the Norse had crystal devices that would allow them to see the location of the sun through overcast and that similar devices were used in the earliest aviation “over the pole” navigation. They also had devices to determine relative latitude. Lief Erickson had sailing directions from an earlier Norse mariner, who had been blown off course in a storm, when he sailed to Nova Scotia.

  2. That is so very cool. I agree with LL on the whole fortitude and will, but I think there may also have been a little tilt to their sanity as well.

    There’s a line in the Flash Gordon movie from the 80’s that jumped into my head. “Pathetic earthlings. Hurling your bodies out into the void, without the slightest inkling of who or what is out here. If you had known anything about the true nature of the universe, anything at all, you would’ve hidden from it in terror.”

    While it wasn’t space it was still a great unknown. Thankfully there are brave, adventurous souls who did it and still do.

  3. I was fascinated by the contents of my dad’s flight kit, which I first viewed around 1958. I am SURE that the contents changed over time, but the last time I looked inside his case was 1969, and he had who-knows how many navigating devices in there. I remember multiple mysterious circular slide rules, protractors, see-through rulers,grid sheets, and the exotic ‘V’ shaped devices, with a bit of lead on one end, and a sharp needle-like pin on the other, and you could adjust the angle, and spin it with the nubbin coming out of the base of the V. I learned, much later, that he called those ‘dividers.’ They were FASCINATING devices to play with for a five year old, but alas, I learned nothing from them at that age.
    I still have a set of his dividers. It’s a precision instrument, kept in a felt-lined case.

  4. LL- Agreed! The basics STILL work even with the advent of technology we have today. And USNA is teaching Cel Nav again!

    NRW- BROAD beams… 😉

    Tole- Agreed!

    Pat- I still have my nav kit too… 😀

  5. Sometime in the 1980’s, I think, there was a Sky & Telescope article about the lowly digital watch. Not the fancy do-everything ones, no, but the cheapest thing to be had at the time. And how, though it did not keep “perfect” time, the imperfection was *predictable* and *constant* [gain or loss of the SAME number of seconds every day/week]. Their conclusion: Navigators of old would have killed for such a wondrous device.

  6. There is something even weirder than that. Micronesian Stick Charts. Micronesians navigated all over the central Pacific by charting currents and ‘feeling’ the water, and made charts of small sticks showing the flows and motions of currents, using shells for various atolls.

    Obligatory Wiki reference: https://en.wikipedia.org/wiki/Marshall_Islands_stick_chart

    My family brought a few back from our stay out that way. Really beautiful, and if you know which atolls the shells are, you can get a high quality ocean chart and see the same motions as those marked in the chart.

    The genius of man is unbound, well, except when socialism is applied…

  7. Thanks to LL for the “above/below the clouds” cAnomment.
    Watching “The Curse of Oak Island” I’m amazed to learn the whole story of Cristobal Colombo “discovering the new world” is probably off by 200 years or so. And the idea of sailing out in a wooden ship to explore, knowing if you ground your vessel along the way somewhere there may be no chance to return?
    What was it someone said about carryin’ ’em around in a bushel basket?

    • The Norse made it in the 900-1000s range. Their sagas are full of savage, half naked Skraelings (which means ‘Stranger’ or ‘Barbarian.’) That whole first episode when the modern people were dealing with Viking-Age cold weather gear? Maybe, but considering that at the 900-1100AD range, the whole North was 5-10 degrees on average warmer than today, well, Greenland in the 1000’s was very green, lots of grass and low bushes. The last Norse/Viking settlement was lost due to the cooling trend and mini-iceage in the 1330’s to 1360’s or so.

      The Irish were also supposed to have made it, back in the 1300’s when it was much cooler. In a hide boat. But, well, Irish.

      Funny thing about Cristobal Colombo that most people don’t know is, though most people of the time, especially educated people, knew the world was round, they thought it was considerably larger than the 18,000+ circumference figure that Colombo used for his “Go West” expedition. His figures were wrong, and they’ve been teaching the wrong thing in public schools ever since. Go figure. Ah, rambling, must stop…

      • That would be, the whole first episode of “America’s Lost Vikings.” I really much cite my sources better, lest someone consider me a progressive…

        • Good Ol’ Chris Colombo was an assistant to his father, also a famous navigator. They had voyaged as far north and west Reykjavik, Iceland. When Chris sailed from Spain in 1492 he knew full well there was land to be found. Only his math was off, not the concept.

  8. Orvan- THAT is why chronographs are so expensive… sigh And yes they would have.

    Beans- Exactly! I’ve seen those and they are dead on, pardon the pun…

    GB- Agreed! 🙂

  9. Your 5-10 mile accuracy in a moving aircraft is amazing.
    Patrick Moore, the lunar astronomer, in his memoirs told of a time in WW2 of stellar navigation.
    He was standing on the end of a jetty on Canada’s Atlantic coast. Using his sextant he ‘shot’ the relevant stars. On calculating his position he was astonished to find he was 30 miles inland!

  10. My navigation skills are limited to land. Give me a topo map and a compass and I’m good. The thought of sailing out of sight of land … well, I’m glad there are people like you who can do it.

  11. Frank- We had excellent training, and practiced routinely! Our butts depending on us being able to actually get us home, and we took it seriously!

  12. Morning stars, evening stars, sun lines during the day. The latter only worked if you were on a steady course and speed so you could DR the later lines back to get a fix.

    Fun times.

  13. In the modern age, I remember a C-5A Nav bitching because he was 0.5 miles off when aligning for long straight final to Hickam (Hawaii) after coming from Travis (Frisco). Wrote up the inertial system. Yeah, well…

    I repaired sextants (mostly the timers) and remember C-141 crews hooking oxygen hoses up to the ceiling port and using the combo as a vacuum (Venturi) to clean the flight deck. I was always happy to report crews to HHQ when they ended up grounding aircraft because the port wouldn’t close due to debris jamming it (Chex and peanuts particularly nasty) — delayed crew, bird, and cargo waiting for my part from the mainland, change time, and sealant curing time. Funny how crews delayed in Hawaii didn’t seem to mind much and never seemed aware of what they caused.

  14. CM- Great point! Since we only flew 12 hours, and it was usually four hours out/back, we didn’t have those options.

    Bob- Sigh… Not surprised.