Not a war, just a sextant question. - SailNet Community
 36Likes
Reply
 
LinkBack Thread Tools
post #1 of 103 Old 01-19-2012 Thread Starter
Senior Member
 
PaulfromNWOnt's Avatar
 
Join Date: Aug 2010
Location: Fort Frances, ON, CA
Posts: 342
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 5
 
Not a war, just a sextant question.

Seriously, I'm just curious:

On E-bay I can buy a Davis plastic sextant for anywhere from 40 to 120 dollars depending more on model than condition.

Would I really be that much farther ahead to do that than to buy a metal replica that I could "tweak" for around 60 to 80?

At this point, a small consistent error is something I could live with as I'm not planning to dock my boat with it. To help with my point, I'm currently using a non WAAS enabled gps. The way I see it is that as long as I'm using the correct datum, my gps is still more accurate than a pencil dot on a 1:50,000 topo map, and I'm good with that. While unaware that I was using the wrong datum in one circumstance I still managed to extrapolate my actual position.
PaulfromNWOnt is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 103 Old 01-19-2012
Bristol 45.5 - AiniA
 
Join Date: May 2006
Posts: 3,851
Thanks: 5
Thanked 96 Times in 84 Posts
Rep Power: 10
 
I think that it can be fun to use a sextant but for positioning it is really very inaccurate. If you get within a mile have done well - and I know I will get rained on by all of the 'what if all the GPS satellite fall out of the sky crowd?' If you just want to know where you are, get a backup GPS. I have a Garmin 12 that works just fine after many years. I turn it on about once a month while cruising - sometimes I have to tell it which part of which ocean we are in to help it get started.
PaulfromNWOnt likes this.

Back home on Lake Ontario after something over 36,000 nm circumnavigator. Not surprisingly there is a lot of stuff I want to get done on Ainia both cosmetically and functionally. Getting an early start so it will be ready to go for next summer (Lake Superior?).
killarney_sailor is offline  
Quote Quick Reply Share with Facebook
post #3 of 103 Old 01-19-2012
Senior Member
 
Boasun's Avatar
 
Join Date: Feb 2007
Location: New Orleans, LA
Posts: 3,070
Thanks: 1
Thanked 0 Times in 0 Posts
Rep Power: 10
   
Sextants are great for finding your position, Especially when you are far out on the Ocean. When you come in sight of land you transition to coastal piloting.

The nasayers of "archatic" methods of Navigation really don't care or want to invest the time in learning those skills. Now I do enjoy the gps. But in my case I have a C-Plath sextant that I'm comfortable in using. Was using sextants before GPS came into being and never had any confusion as to were I was at on this big blue marble.

Recommend you acquire the best sextant you can afford and learn to use it. But it takes practice, lots of practice in building your skills. Remember that sextants were used for a few centuries before GPS came about.

And there have been many cases where mariners have run aground because they depended on the GPS far to many time.

1600 Ton Master, 2nd Mate Unlimited Tonnage

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Maritime Instructor
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

S/V Rapture

Last edited by Boasun; 01-19-2012 at 10:11 PM.
Boasun is offline  
Quote Quick Reply Share with Facebook
post #4 of 103 Old 01-19-2012
Sailors do like Heineken!
 
chrisncate's Avatar
 
Join Date: Jan 2010
Location: Maryland
Posts: 4,574
Thanks: 18
Thanked 34 Times in 34 Posts
Rep Power: 6
 
Quote:
Originally Posted by Boasun View Post
Sextants are great for finding your position, Especially when you are far out on the Ocean. When you come in sight of land you transition to coastal piloting.

The nasayers of "archatic" methods of Navigation really don't care or want to invest the time in learning those skills. Now I do enjoy the gps. But in my case I have a C-Plath sextant that I'm comfortable in using. Was using sextants before GPS came into being and never had any confusion as to were I was at on this big blue marble.

Recommend you acquire the best sextant you can afford and learn to use it. But it takes practice, lots of practice in building your skills. Remember that sextants were used for a few centuries before GPS came about.

And there have been many cases where mariners have run aground because they depended on the GPS far to many time.
I can't seem to get it (celestial nav) from fancy book lernin.. can you explain in simple human terms how you do the calculations after shooting the sight (the one thing I can do)?
chrisncate is offline  
Quote Quick Reply Share with Facebook
post #5 of 103 Old 01-19-2012
Senior Member
 
Boasun's Avatar
 
Join Date: Feb 2007
Location: New Orleans, LA
Posts: 3,070
Thanks: 1
Thanked 0 Times in 0 Posts
Rep Power: 10
   
There are formats that are easy to use. I have Weems & Plath (H.O. 229 Sight solver) that can ease your way into understanding the math involved. And there are a couple of books that simplify Celestrial navigation.

1600 Ton Master, 2nd Mate Unlimited Tonnage

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Maritime Instructor
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

S/V Rapture
Boasun is offline  
Quote Quick Reply Share with Facebook
post #6 of 103 Old 01-19-2012
Morgan 33 O.I. Perryville
 
travlineasy's Avatar
 
Join Date: Dec 2010
Location: Maryland
Posts: 3,476
Thanks: 3
Thanked 149 Times in 132 Posts
Rep Power: 5
 
I've only tried two sextants during the past decade, including the Davis plastic sextant sold by West Marine. The best accuracy I experienced was approximately +/- 6 miles, which would be fine in the middle of the ocean. So, if both of my GPS systems failed, and I was well offshore when the failures occurred, then the GPS would be a handy gadget to have onboard. However, I've used Loran-A, Loran-C and GPS, all since their inception, and never experienced a failure. Either I'm darned lucky, or electronic navigation systems are very reliable.

I guess from my perspective, having a good, electronic backup system is a far better investment, especially if you're not going to spend endless days and weeks offshore. However, if you are going offshore, maybe crossing the oceans, then as stated above, purchase the best sextant you can afford--it may end up being your only backup, navigational system.

Good luck on whatever you decide upon,

Gary
travlineasy is offline  
Quote Quick Reply Share with Facebook
post #7 of 103 Old 01-19-2012
Sailors do like Heineken!
 
chrisncate's Avatar
 
Join Date: Jan 2010
Location: Maryland
Posts: 4,574
Thanks: 18
Thanked 34 Times in 34 Posts
Rep Power: 6
 
::sigh::

Still nothing. What is it with the secret society of celestial..

Thanks anyway... I'll look at what you recommended.
chrisncate is offline  
Quote Quick Reply Share with Facebook
post #8 of 103 Old 01-19-2012
Morgan 33 O.I. Perryville
 
travlineasy's Avatar
 
Join Date: Dec 2010
Location: Maryland
Posts: 3,476
Thanks: 3
Thanked 149 Times in 132 Posts
Rep Power: 5
 
Chris,

If you wish, I can email you a great book on learning how to use a sextant. It's a down to earth book that puts things in plain, easy to understand language. Just email me and I'll send it via return email.

Cheers,

Gary
rgscpat likes this.
travlineasy is offline  
Quote Quick Reply Share with Facebook
post #9 of 103 Old 01-19-2012
Sailors do like Heineken!
 
chrisncate's Avatar
 
Join Date: Jan 2010
Location: Maryland
Posts: 4,574
Thanks: 18
Thanked 34 Times in 34 Posts
Rep Power: 6
 
Quote:
Originally Posted by travlineasy View Post
Chris,

If you wish, I can email you a great book on learning how to use a sextant. It's a down to earth book that puts things in plain, easy to understand language. Just email me and I'll send it via return email.

Cheers,

Gary
I will (and thank you), however I must warn you I have already bought a few books that billed themselves as easy to understand, and I couldn't understand them.. I am terrible at math, math theory, and anything to do with math...

I'll shoot you an email and give it a shot though...
chrisncate is offline  
Quote Quick Reply Share with Facebook
post #10 of 103 Old 01-19-2012
Morgan 33 O.I. Perryville
 
travlineasy's Avatar
 
Join Date: Dec 2010
Location: Maryland
Posts: 3,476
Thanks: 3
Thanked 149 Times in 132 Posts
Rep Power: 5
 
It's on its way.

Good Luck,

Gary
travlineasy is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
sextant muskyguide Gear & Maintenance 9 12-28-2010 02:45 PM
Sextant jerryrlitton General Discussion (sailing related) 17 09-13-2010 11:00 AM
christmas toy...sextant--need help QuickMick Gear & Maintenance 24 01-09-2010 11:24 PM
New guy - sextant question tonycondon Gear & Maintenance 6 08-04-2009 09:51 PM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome