NavList:

   

Reply

On Thu, 15 Jan 2009 01:04:44 -0700, Nicol�s de Hilster  
 wrote:

> These circle charts were made on the job by the surveyor and showed only
> what the navigator needed, in most cases that were a few known points, a
> bit of coast line, an outline of the working area and of course the
> circles. The charts were used for small area's of only a few kilometres
> in diameter and usually made of paper (A1 or A0 size).

As a practical method, did you calculate the centers of the circles (on  
the perpendicular bisectors of each line joining pairs of shore stations)  
for drawing the chart of current interest?  Or did you use an adjustable  
triangle, set to the double angle of the "observation angle", and find the  
center for the circle of that observation angle graphically?   Or  
possibly, put pins in your beacon positions, set an adjustable triangle  
(made of two pivoting straight edges) and use a (mechanical) pencil in the  
vertex to trace out a circle.  Also, what would be the average degree  
spacing of the chart's circles?

It seems as though there is a fair amount of work to set up a chart like  
that without modern aids such as a computer, and you would have to make a  
large number of observations to make it worth while.  I wish I were  
skilled enough to use something like Gnuplot for doing a circle chart of  
our river-bottom flats, using some reference points 200 to 300 feet above  
the somewhat uneven work area.

Easier to locate your position using a plane table or theodolite than with  
a sextant; and many software packages for total stations include the three  
point problem solutions.

-- 
Richard . . .

Using Opera 9.2.4 after the "Dog" died

--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---

   

Reply