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Old 28-07-2012, 08:25   #1
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Recommended Sources to Lear To Use a Sextant, etc

Anyone have the skinny on a site, or course, to learn how to use a sextant properly? Basic navigation without electronics is going to be a must, as far as I'm concerned, because if I'll be going out of sight of land and my GPS pukes, I'd like to do a bit better than guessing and hoping my guess is right, as far as finding safe harbor. I could get back with dead reckoning and compass course, but still not know where I am in relation to where I want to be, as far as finding the port entrance, and above all else, I don't want to be one of those idiots who has to call the Coasties because I'm just lost.
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Old 28-07-2012, 08:31   #2
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Re: Recommended Sources to Lear To Use a Sextant, etc

This should get you started
Celestial Navigation
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Old 28-07-2012, 08:36   #3
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Re: Recommended Sources to Lear To Use a Sextant, etc

Thanks for the fast response, Nigel. That's perfect for getting me started, and it just got loaded to our Kindles.

Fair winds!
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Old 28-07-2012, 08:46   #4
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Re: Recommended Sources to Lear To Use a Sextant, etc

Dont get too bogged down with all the formula in that book.
Here is a link to Sight Reduction Tables
Maritime Safety Information

If you google "using a sextant" you'll find some easier explanations, plus a couple on you tube
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Old 28-07-2012, 09:06   #5
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Re: Recommended Sources to Lear To Use a Sextant, etc

Star Path has an on-line celestial class. See Starpath School of Navigation Title Page.

Many books available too. One I like is "Practical Celestial Navigation" by Susan Howell. Not sure about current availability though.
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Old 28-07-2012, 09:40   #6
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Re: Recommended Sources to Lear To Use a Sextant, etc

This sextant users guide from Andy Evens is a great help.
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Old 28-07-2012, 09:43   #7
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Re: Recommended Sources to Lear To Use a Sextant, etc

Start with sunsights and advancing Lines of position. Once you master that, stars will be easier.
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Old 28-07-2012, 10:03   #8
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Re: Recommended Sources to Lear To Use a Sextant, etc

I learned from Celestial Navigation for Yachtsman by Mary Blewett. Skips all the complex math and gets straight to how to take a sight and get a position using the Nautical Almanac and HO249 tables. Includes just enough science and theory so you can understand what you're doing.
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Old 28-07-2012, 10:42   #9
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Re: Recommended Sources to Lear To Use a Sextant, etc

+1 for skipmac!!! thats the way to go forget all the heavy math ways to learn it!! just my 2 cents I keep her book handy all the time and read it thru a couple of times a year !! Works for me !!
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Old 28-07-2012, 11:07   #10
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Re: Recommended Sources to Lear To Use a Sextant, etc

You are going to need a nautical almanac. I found "The Online Nautical Almanac" to be a helpful resource. There are other website/PC applications that print the almanac pages too.

When learning, I found it helpful to double-check your site reductions using one of the many site reduction calculators.

Good luck/enjoy,
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Old 28-07-2012, 11:15   #11
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Re: Recommended Sources to Lear To Use a Sextant, etc

Just as a side note: sextants are useful for other purposes, such as determining heights of things when the distance is known, determining distance offshore when the heights of landmarks are known (you flip it on its side and work out the angles).

Or, as our family did recently, using the sun filters to observe the transit of Venus. That was fun.
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Old 28-07-2012, 13:19   #12
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Re: Recommended Sources to Lear To Use a Sextant, etc

Having sailed a 28' E-scow, where are you going to find storage 20' inland scow for a sextant and references in addition to the food and water needed to sail out of sight of land.
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Old 28-07-2012, 17:57   #13
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Re: Recommended Sources to Lear To Use a Sextant, etc

Quote:
Originally Posted by Adelie View Post
Having sailed a 28' E-scow, where are you going to find storage 20' inland scow for a sextant and references in addition to the food and water needed to sail out of sight of land.
I just bought another boat. I also have a sailMFG Bandit 19 keelboat. It's a little Pocket Cruiser, but seaworthy, and totally another world as compared to scows. My next boat will be something bigger than that, too.

The Bandit is primarily a coastal boat, but solid enough for some offshore stuff, like maybe the Bahamas or the Dry Tortugas, and if I'm going out of sight of land, I want to know where I am, etc, and have this horrible habit of the attitude, "While I enjoy the convenience of GPS, I want to be able to do without, too."

Now, I may be crazy, but I wouldn't take an inland scow anything close to offshore, or even Lake Michigan.
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Old 28-07-2012, 19:35   #14
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Re: Recommended Sources to Lear To Use a Sextant, etc

Here's what I would do, not for learning, but in actual use.

Get:
-a Davis Mark3
-the Long-term almanac by Geoff Kolbe.

The Mark3 is of limited accuracy, but sufficient for a landfall with limited outlying submerged dangers.

The almanac is good until 2050 for the sun and stars and it contains a compact sight reduction table.

If I were out cruising right now I would pull these out once a week, shoot a body and plot the line against a GPS reading taken at the same time (press the MOB button and ignore until you have finished the plot). This would keep me in practice with the method that was easiest to carry (not the easiest method to use) and give me on-going feedback on how well I was doing.

Also get:
3 cheap casio watches set to GMT/UTC/Zulu time & date.
a steel cash box
a Rite-in-the-Rain note pad
a really cheap really small GPS
Rechargable batteries
Solar battery charger for same.

All these are kept in the cash box, which could then be kept in a Pelican case for water and humidity protection. The cash box is for protection against lightning strikes.

Every week when I shoot practice line, I check each watch against an external time source, shortwave is best, but GPS time will do if you keep track of how much it has varied from UTC. UTC occasionally has leap seconds which GPS doesn't. Currently you subtract 16sec from GPS to get UTC (GPS, UTC, and TAI Clocks). I would not reset each watch weekly, I would log the error in the Rite-in-the-Rain so I knew what the error rate was. In the even that the watches survive whatever kills all the other electronics I know what the most recent error was for each watch, and can project forward what that error will be so as the error changes. Three watches is so that you can tell if one of the watches goes seriously off the rails, and so you can average all of them if there isn't one that is obviously wrong.

The rest of the items are an attempt to not need the sextant.

Altogether you are looking at $100-150 for sextant stuff plus pelican case,GPS,charger and batteries.

Davis Mark 3 Marine Sextant from Wholesale Marine
Amazon.com: Long Term Almanac (9780914025108): Geoffrey Kolbe: Books

First Alert Locking Steel Cash Box with Removabl... : Target
Amazon.com: Casio Men's W800H-1AV Classic Digital Sport Watch: CASIO: Watches
Amazon.com: Garmin Geko 201 Waterproof Hiking GPS (Yellow): GPS & Navigation
Amazon.com: AA and AAA Solar Battery Charger - Charge Your Batteries Via USB or Sun Power - Features Also Include a Battery Tester and USB Output for Charging Cell Phones, iPods/mp3s, and More: Electronics
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Old 28-07-2012, 22:29   #15
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Re: Recommended Sources to Lear To Use a Sextant, etc

Thanks, Adelie! Very much appreciated.
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