Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 28-07-2012, 09:25   #1
Registered User
 
Tom Stormcrowe's Avatar

Join Date: Jul 2012
Location: Indiana
Boat: 1984 Johnson Boatworks Inland Scow, 20' and a 1975 sailMFG Bandit 19 Pocket Cruiser
Posts: 204
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.
__________________

__________________
"Dum vivimus, vivamus! -- 'While we live, let us live!"-Heinlein (Among others)
My Refit and Travel Blog
Tom Stormcrowe is offline   Reply With Quote
Old 28-07-2012, 09:31   #2
Moderator
 
nigel1's Avatar

Cruisers Forum Supporter

Join Date: Oct 2009
Location: Manchester, UK
Boat: Beneteau 473
Posts: 5,183
Re: Recommended Sources to Lear To Use a Sextant, etc

This should get you started
Celestial Navigation
__________________

__________________
Nigel
Beneteau 473
Manchester, UK
nigel1 is offline   Reply With Quote
Old 28-07-2012, 09:36   #3
Registered User
 
Tom Stormcrowe's Avatar

Join Date: Jul 2012
Location: Indiana
Boat: 1984 Johnson Boatworks Inland Scow, 20' and a 1975 sailMFG Bandit 19 Pocket Cruiser
Posts: 204
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!
__________________
"Dum vivimus, vivamus! -- 'While we live, let us live!"-Heinlein (Among others)
My Refit and Travel Blog
Tom Stormcrowe is offline   Reply With Quote
Old 28-07-2012, 09:46   #4
Moderator
 
nigel1's Avatar

Cruisers Forum Supporter

Join Date: Oct 2009
Location: Manchester, UK
Boat: Beneteau 473
Posts: 5,183
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
__________________
Nigel
Beneteau 473
Manchester, UK
nigel1 is offline   Reply With Quote
Old 28-07-2012, 10:06   #5
Registered User

Join Date: Dec 2010
Location: W Carib
Boat: Wildcat 35, Hobie 33
Posts: 7,925
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.
__________________
belizesailor is online now   Reply With Quote
Old 28-07-2012, 10:40   #6
Registered User
 
callmecrazy's Avatar

Join Date: Jun 2010
Boat: Tartan 30
Posts: 1,548
Images: 1
Re: Recommended Sources to Lear To Use a Sextant, etc

This sextant users guide from Andy Evens is a great help.
__________________
My Blog
callmecrazy is offline   Reply With Quote
Old 28-07-2012, 10:43   #7
Registered User

Join Date: Oct 2010
Location: Abaco, Bahamas/ Western NC
Boat: Nothing large at the moment
Posts: 820
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.
__________________
Tingum is offline   Reply With Quote
Old 28-07-2012, 11:03   #8
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 12,374
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.
__________________
The water is always bluer on the other side of the ocean.
skipmac is online now   Reply With Quote
Old 28-07-2012, 11:42   #9
Registered User

Join Date: Nov 2011
Location: Montegut LA.
Boat: Now we need to get her to Louisiana !! she's ours
Posts: 3,421
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 !!
__________________
Bob and Connie
bobconnie is offline   Reply With Quote
Old 28-07-2012, 12:07   #10
Registered User
 
Capt.Don's Avatar

Join Date: Aug 2010
Location: Altadena, CA
Boat: Tartan 3500
Posts: 611
Images: 1
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,
Don
__________________
Capt.Don is offline   Reply With Quote
Old 28-07-2012, 12:15   #11
Registered User
 
S/V Alchemy's Avatar

Join Date: May 2008
Location: Toronto
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,576
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.
__________________
Can't sleep? Read www.alchemy2009.blogspot.com for fast relief. Can't read? Avoid www.volumesofsalt.blogspot.com, because it's just personal reviews of sea books.
S/V Alchemy is offline   Reply With Quote
Old 28-07-2012, 14:19   #12
Moderator
 
Adelie's Avatar

Join Date: Feb 2010
Location: La Ciudad de la Misión Didacus de Alcalá en Alta California, Virreinato de Nueva España
Boat: Cal 20
Posts: 4,599
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.
__________________
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
SailboatData
Adelie is online now   Reply With Quote
Old 28-07-2012, 18:57   #13
Registered User
 
Tom Stormcrowe's Avatar

Join Date: Jul 2012
Location: Indiana
Boat: 1984 Johnson Boatworks Inland Scow, 20' and a 1975 sailMFG Bandit 19 Pocket Cruiser
Posts: 204
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.
__________________
"Dum vivimus, vivamus! -- 'While we live, let us live!"-Heinlein (Among others)
My Refit and Travel Blog
Tom Stormcrowe is offline   Reply With Quote
Old 28-07-2012, 20:35   #14
Moderator
 
Adelie's Avatar

Join Date: Feb 2010
Location: La Ciudad de la Misión Didacus de Alcalá en Alta California, Virreinato de Nueva España
Boat: Cal 20
Posts: 4,599
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
__________________
A house is but a boat so poorly built and so firmly run aground no one would think to try and refloat it.
SailboatData
Adelie is online now   Reply With Quote
Old 28-07-2012, 23:29   #15
Registered User
 
Tom Stormcrowe's Avatar

Join Date: Jul 2012
Location: Indiana
Boat: 1984 Johnson Boatworks Inland Scow, 20' and a 1975 sailMFG Bandit 19 Pocket Cruiser
Posts: 204
Re: Recommended Sources to Lear To Use a Sextant, etc

Thanks, Adelie! Very much appreciated.
__________________

__________________
"Dum vivimus, vivamus! -- 'While we live, let us live!"-Heinlein (Among others)
My Refit and Travel Blog
Tom Stormcrowe is offline   Reply With Quote
Reply

Tags
sextant

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 11:55.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.