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Sextant... any recommendations?

Old 08-08-19, 09:07 PM
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Seattle Forrest
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Sextant... any recommendations?

I want to make sure I don't get lost when I ride.

I know there are Garmins out there, but screw that. The sky is free. And GPS can go dark.

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Old 08-08-19, 09:11 PM
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Did you read up on how a sextant works? and what other 'things' you'll need to get a proper reading? and the only times of day it can be used to get an accurate reading?
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Old 08-08-19, 10:05 PM
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Oh come on, you make it sound hard. Shackleton made it all the way to South Georgia Island with a sextant, and they barely used it.
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Old 08-08-19, 10:26 PM
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Stay east of the Cascades. Clouds affect sextants even more than GPS units. (When we sailed across the Atlantic, 12 days, we could use our sextant on three of them. One in the middle of the ocean where our exact location just wasn't that important, the day we made landfall and thankfully the day before landfall. We made our last course change based on our three running fixes. And hit our target spot on. Quite satisfying. (Our Loran gave great fixes until we were with 200 miles of Ireland - GPS was very expensive, huge and heavy and not very accurate then. In other words, the Loran worked well until it mattered.)

You'll also need either a good navigation calculator or some serious schooling and tables or that sextant will not tell you more than your latitude. Get one with an artificial horizon because in your neck of the woods, the actual isn't always there to be found. Pack it carefully. They do not like bike vibration.
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Old 08-09-19, 07:57 AM
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Sextant? Wow, you are getting all fancy. I use a stem mounted sundial and some bar end dowsing rods.
Occasionally I bring my homing pigeon and just follow it.
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Old 08-09-19, 08:18 AM
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I have an old Davis plastic sextant. It doesn’t have turn-by-turn.
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Old 08-09-19, 08:23 AM
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In order to use it you will need a very accurate chronograph device.

Likely the most accurate might be a GPS as it's getting the atomic time off the satellites.
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Old 08-09-19, 08:58 AM
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Originally Posted by 79pmooney View Post
Get one with an artificial horizon because in your neck of the woods, the actual isn't always there to be found.
I thought an artificial horizon was only for training? How do you set it properly when you don't have one to start with?
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Old 08-09-19, 08:59 AM
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Originally Posted by Seattle Forrest View Post
And GPS can go dark.

Try getting a fix when you have no sun or no stars.
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Old 08-09-19, 09:07 AM
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Sextants are nowhere near as fun as the name leads you to believe.
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Old 08-09-19, 09:32 AM
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Originally Posted by hazetguy View Post
Sextant? Wow, you are getting all fancy. I use a stem mounted sundial and some bar end dowsing rods.
Occasionally I bring my homing pigeon and just follow it.
Oh man, I should get some dowsing rods for when I get thirsty!
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Old 08-10-19, 04:40 AM
  #12  
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Originally Posted by Steve B. View Post
In order to use it you will need a very accurate chronograph device.

Likely the most accurate might be a GPS as it's getting the atomic time off the satellites.
A good digital timex is more accurate than what Shackleton carried.
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Old 08-10-19, 04:47 AM
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Good starter...
https://www.davisinstruments.com/pro...rk-15-sextant/

Something to leave on the office desk...
https://www.harborfreight.com/vintag...BoCvakQAvD_BwE


After you've learned how to use one... and plan on crossing oceans... keep your first one as a backup, then look at upgrading...
https://www.celestaire.com/selecting-a-marine-sextant/
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Old 08-10-19, 04:50 AM
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Old 08-10-19, 08:51 PM
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You live on the coast.

I'd be asking somebody who has done lots of this in small vessels . . . offshore.

And that's a 28 ft Herreshoff canoe yawl: "Rozinante"
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Old 08-12-19, 07:12 AM
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Now that's a yar looking vessel!
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Old 08-12-19, 04:51 PM
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You can use an analog watch as a compass. Point the hour hand at the sun, and read the direction from 12:00. At noon, 12:00 points south. At sunrise, 12:00 points West(ish). At sunset, 12:00 points East(ish). There's an old boy scout rule, I forget, with a multiplier that makes it a bit more accurate. Probably depends on latitude, actually.
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Old 09-28-19, 09:53 AM
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They're pretty, displayed in a curio cabinet. Surveyor's vintage transits also look good.
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Old 10-07-19, 02:29 PM
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I have my grandfather's ship captain sextant which is huge and bolted into a wooden box. I think for cycling use a plastic one is more practical.

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Old 10-09-19, 08:58 AM
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Originally Posted by Seattle Forrest View Post
I want to make sure I don't get lost when I ride.

I know there are Garmins out there, but screw that. The sky is free. And GPS can go dark.

Sextant: A Young Man's Daring Sea Voyage and the Men Who Mapped the World's Oceans, by David Barrie. Kindle version is available for free from Overdrive which is available from many public libraries.
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Old 10-09-19, 10:05 AM
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We sailed the Atlantic in 1986 with LORAN, an RDF, VHF and shortwave radios, compasses, hand bearing compass and sextant. St. John's, Newfoundland to Baltimore, Ireland. Fastnet Rock was our waypoint. GPS at that time was "fuzzy", ie good to around a 1/4 mile, plus cost ~$5000 and the units were huge and heavy so we passed on it.

LORAN worked very well until we were about 200 miles from Ireland. Then it started giving us two fixes 10 miles apart. Pretty useless for navigating the very jagged Irish coast. (We had only seen the sun one day mid-Atlantic and in the eye of the first storm.) On our last day at sea, sun, finally! We bathed in solar heated warm water, put on fresh clean clothes kept in sealed plastic bags - for 9-days, everything anywhere else was saturated with water. 100%+ humidity, gallons of water coming in every time someone came in from on deck and condensation on everything metal or glass. That day we took 3 sun sights, morning, noon and afternoon, plotted those and made our last course correction. At midnight, we got an RDF bearing on the big radio transmitter in SW Ireland for shipping traffic. Right where it should be. 4am, the flash of the one of Ireland's great west coast lighthouses could be seen though the lighthouse itself was well below the horizon. Likewise, right where it should be.

10am the next morning, we sighted Fastnet Rock, directly ahead. Rounded it an hour later and headed for the harbor at Baltimore.

Yes, we still had electronics and had that been 30 years later, handheld GPS would have been a no-brainer. But in a longer, wetter and rougher voyage, it isn't hard to imagine most electronics being soaked with salt water and not working. We were only out for 12 days, never saw more than ~60 nmh winds and 25' seas. Going around Cape Horn, that could be 90+ nmh winds and 60+' seas. If the final destination was an island after that wetting, a sextant might be VERY usefull! Even now.

Ben
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