Sextants in general

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
diver dave said:
Consider, if you will, the issue of navigation to mars. GPS, of course, is not in the cards. BUT, they (JPL) are talking about 1km accuracy in "radio/celestial" nav. Impressive, indeed.
Click to expand...


It is my plan to immigrate to Mars in 2097. But I dont think I will need my Sex Tent (portable house of ill repute).
 
There is little need for a sextant. If you were crossing an ocean and lost all electronics, then a sextant would be handy. Realistically, for coastal cruising this is unnecessary.

On the east coast, you simply point the compass West and go until the land is in sight. If you're on the west coast, head east.
 
Shrew said:
There is little need for a sextant. If you were crossing an ocean and lost all electronics, then a sextant would be handy. Realistically, for coastal cruising this is unnecessary.

On the east coast, you simply point the compass West and go until the land is in sight. If you're on the west coast, head east.
Click to expand...




We are still here...LOL On the south coast you head north
 
A sextant wont keep you from hitting a rock, just an island.
 
power squadron

Celestial Nav is worth doing just for the experience and insight on how it was done in the old days. The Astra is an excellent instrument and by far the best quality for the money if you are buying new. The Davis plastic sextants are perfectly satisfactory for learning and have a nice bright viewfinder. To learn, I recommend the US Power Squadron JN class.

Dan
 
So is making soap.... :)

And when you are done, you have something more and it will last longer than a fix....:thumb:
 
Based on these comments on the value of experiencing it for old times sake, I would rather learn to navigate the old Tahitian way where the navigator stood spread legged in the bow and mapped the wave patterns by the swing of his balls. Much cheaper to pursue, easier to do and much more fun. I have done the sextant thing and it is none of these.
 
jimisbell said:
Based on these comments on the value of experiencing it for old times sake, I would rather learn to navigate the old Tahitian way where the navigator stood spread legged in the bow and mapped the wave patterns by the swing of his balls. Much cheaper to pursue, easier to do and much more fun. I have done the sextant thing and it is none of these.
Click to expand...

and the lady navigators, they had to bring a friend?

Sorry, that was too obvious and I couldn't pass it up.
 
Last edited:
So Columbus coined the phrase "swing and a miss" long before baseball was invented?
 
The Tahitian society was patriarchal. So probably no women navigators. And lacking the physical attributes, any one who sailed with a female navigator probably never returned.....LOL
 
jimisbell said:
The Tahitian society was patriarchal. So probably no women navigators. And lacking the physical attributes, any one who sailed with a female navigator probably never returned.....LOL
Click to expand...

No wonder we have never heard of female navigators.
 
There are at least three systems up there. Only in the US do we think we are dependent on the US GPS system.
 
The most likely terror attack on the West or USA will be a cyber attack.

A small nuke over the East coast would end GPS , banking and a lot of communications and electric service.

There are many ways to navigate that do not require GPS , how many are onboard your boat, , and when is the last time you used them?
 
FF said:
..
There are many ways to navigate that do not require GPS , how many are onboard your boat, ,..
Click to expand...

True, but vanishingly few that are a result of pushing buttons. :thumb:

The radio aids are quite limited. Not even sure I can name all the obsolete ones. Only the ones I know: Omega, Decca, Loran A, loran B, transit, LF beacons. Still a lot of broadcast AM stations out there that can be triangulated with. and, quite a number of aircraft NDB's still there with ranges maybe up to a hundred miles. But, middle of an ocean, you are pretty much stuck with celestial, inertial (ha!) and compass/dead reckoning/speed log or asking a passing vessel (this one I've seen). There are a variety of LEO sats that transmit; so, I suppose you could set up, in advance, some tables using ephemerous info to find them and maybe find you. For instance, AMSATs and wx sats. With a suitably large ship, one could envision some highly directional, gyro stab. arrays to determine Az and El. Basically, get LOP using orbiting sats. Difficult to do on a 17 boston whaler looking for an inlet in fog.
 
Last edited:
Consolan was great , in the 1960's although the chart of the Atlantic was only a foot wide , so a thin pencil LOP could be 25 miles wide.

There are still books that explain "double the angle off the bow", but few folks these days have tried it .

How many even have a lead line with 100ft of line aboard?
 
I am currently reading the book about Ed Gillets solo Pacific Ocean crossing on a kayak in 1987. He did this on a shoe string budget, and shear willpower. Sixty something days paddling non stop, and trying to sleep periodically in a fiberglass tube two feet wide. I thought of this thread when I read the following passage regarding what he used for Nav..
 

Attachments

  • C17EA099-DD87-4B14-AF70-96C3CF018424.jpg
    C17EA099-DD87-4B14-AF70-96C3CF018424.jpg
    128.7 KB · Views: 58
FF said:
There are still books that explain "double the angle off the bow", but few folks these days have tried it .
Click to expand...
I use doubling the angle all the time and have a copy of Bowditch's American Practical Navigator on board. Lots of info in that. It was one of the manuals when I was taught navigation in the USN. I shoot bearings and radar ranges partly because it gives me something to do on a long coastal trip and old habits. I run a manual plot because I don't trust GPS, Just like my dad re-added the results of an adding machine because he didn't trust the machine.
 
“Doubling the angle”. Is this where you are headed to a radio beacon and there is a cross current? So, if the vessel is not reducing the cross track error, you double the heading difference, wait 10 minutes and recheck the LOP?
 
You must log in or register to reply here.

Similar threads

J
Books for a ground floor novice
Replies
10
Views
399
Mac2
Mac2
J
Mariners Skipper Course
Replies
7
Views
1K
Symphony
Symphony
J
This Dog Don't Hunt-Sabreline 36 Aft Cabin
Replies
14
Views
771
jtdums
J
Harborseal
Living on a Grand Banks 42 Classic for the Summer
Replies
13
Views
682
mvweebles
mvweebles
A
Aft deck side door mounting / just glue or screws from below?
Replies
0
Views
124
Andiamo2018
A

Latest posts

Back
Top Bottom