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Old 02-23-2018, 03:33 PM   #1
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When I began my love affair with boats and the sea, navigation was a totally different animal than it now is. In some respects, that's a good thing.

Anyone wanting to push off from the shore needed an array of geometric skills, parallel rulers, calipers, protractors, lots of paper, a hundred pencils, a good india rubber and paper charts, which at the time, were not produced in color.

To venture further afield, one needed a radio direction finder (either a cheap, pocket sized transistor radio, or a Lokata-one of which I still have). One also needed a towable log, although they were being replaced by newer technology: As was the case with depth sounders which had evolved from the knotted, leather flagged rope, to a wildly spinning neon light, which I could watch for hours. I was transfixed by the new; but not yet fully convinced to let go of the old.

I also had a VHF radio and, when I could eventually afford it, I bought a second hand Codan 8121 HF radio with both a whip and triatic stay antenna.

Of course, central to the rather important concept of knowing where one was, was the sextant. I had managed to buy a Tamaya brass sextant and learned to use it along with sight reduction tables. The problem with the Tamaya was its weight. With one arm slung around the cap shroud, balancing against wind and waves, while trying to get the blasted sun to sit on the horizon, and to then mark the exact second, it was always a trial to get a decent fix...sometimes an error of 20 or 30 miles was almost unbelievably accurate.

Then I bought a Davis MK25, 'plastic' sextant. Light, sturdy, accurate and, for the time, astoundingly inexpensive. I remember the first time I ever bought a GPS. It was a brand new Magellan which referenced 3 satellites and was on special at the boat show for AU$3000 (US$2100). It was a better bet that a SatNav which I never bothered with, and it allowed me to get a Lat/Long to transfer to my charts which, as far as I was concerned, was the ant's pants. (I still have the Magellan, but it's a bit buggered these days).

For a long time I only used my sextant to view solar eclipses. But then, I recognized people were losing the talent to shoot a sight and I regained my interest...especially when an Aussie mariner developed what is now called an 'app' for a small Sharp pocket calculator. The calculator was renamed the 'Merlin' and essentially removed the need for sight reduction tables and complex mathematics. I began using the sextant again to prove the accuracy of the GPS and to test myself for accuracy. Five miles was brilliant, 10 miles was fair. I also began to use the sextant when travelling coastlines. Triangulating one's position from known coastal marks (using the sextant on it's side) was a fun, seamanlike thing to do, and it gave the hand bearing compass a rest.

Nowadays, I still like paper charts, and use them to plot my course, but chart plotters are just the best thing ever. The downside? Some people go to sea who may not have the full set of seaman's skills. There is, after all, a big difference between someone who merely sails, and a mariner.

But I have recently dusted off the Davis. I bought some new foam inserts from Davis Instruments for the old box and the sextant itself looks almost new, as it was something which always had to be treated with respect and great care.

Oddly enough, after almost half a century of involvement in boats, from casual sailing, to permanent life aboard, to crossing oceans single handed, and now to sailing a few months of the year, I am an old salt...and nothing says it so well as when I see my shadow, short along the side deck, of a man, me, arm slung around the shroud, shooting the sun.

And while I don't eschew the modern, I still occasionally embrace the past. And it made me chuckle recently when I was using my sextant, just for fun, while anchored. On a nearby boat a young teen asked of her parent, "Mum, what's that old man doing"? The response was priceless. "He's using a sextant...it's what real sailors used to use in the olden days, to tell them their position".

Thanks 'Mum'. A real sailor.
I feel like I've earned it.
I belong. But despite my years...'Old Man'...Really?
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Old 02-27-2018, 07:41 PM   #2
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When I joined the Navy, in the olden days, using a sextant and taking sights was considered a very necessary skill and as a Cadet we practiced long and hard. As a result I still have the skill, although very rusty. Once we stop coastal cruising and possibly start ocean passages then it will be time to dust off that skill, buy a cheap sextant and practice once again.
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Old 03-05-2018, 11:56 PM   #3
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I hear navies are re-introducing celestial navigation to recruits, having realized just how easily satellites can be hacked out of commission.
When I began crossing oceans, GPS meant "Gray plastic sextant." I get peace of mind knowing I can figure it out again, any time I may need it.
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Old 03-06-2018, 01:43 AM   #4
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There are currently many Mk15 and MK20 Davis sextants for sale on ebay (USA) for less than $100. Several Mk25s for not much more. Very good deals! Also, check Google Play for celestial navigation apps and this program which is not dependent on phone or internet connectivity. StarPilot TI-89: Celestial Navigation Software
Buy a Mk20 or Mk15 sextant + software + text on celestial nav = >$200. Confound all the bad guys who can hack satellites and impress the heck out of the youngsters.
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Old 03-06-2018, 10:06 PM   #5
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Love my Ebco micrometer plastic sextant. Much easier to use than a vernier model.
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Old 03-07-2018, 01:06 AM   #6
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Have not seen one before. From $29 on eBay.
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Old 03-07-2018, 01:38 AM   #7
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I too became involved with learning how to shoot a site. Had a couple of sextants, engineer by profession so the math was easy enough, downloaded the site tables and practiced. The best I ever got was within 25 miles of my actual position.
You fail to mention that getting an accurate horizon from the deck of a sailboat is near impossible, a small measurement error results in many miles of error in position. Further sextants are only accurate when they have been recently factory calibrated. Then there's dip error, center of sun or moon error, refraction error (atmosphere), and parallax error. I had a wwv receiver for time but I can't imagine how the old timers did it with clocks. GPS, GPS, GPS!!!!!
Great topic though. Thanks Auzzee
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Old 03-07-2018, 02:01 PM   #8
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Cheers Spike. I agree. Sextant vs GPS, is horse vs motor car...but there are times when an'orse could be helpful. Sailing in northern Australia, Indonesia and mainland Asia, the sextant was of less use than on the open ocean, except as a pelorus. But even that use sort-of fell by the wayside when a friend bought me one of the brilliant Autohelm personal electronic compasses in the'80s. Between that and an RDF, I was high-tech personified.

I do think though, that plotting a noon sight on the chart, while out of sight of land, and discovering one's position to be within shouting distance of the DR position was one of the great feelings of sailing. Conversely, I remember the awful feeling of dread after calculating a plot following a week long overcast sky, to find my suspected position was well over 150nm away from my DR. And there was no computer error to blame.

The thought went through my head to 'just keep heading west and bone up on Africaans'.
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