NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Station pointer London UK
From: Alexandre Eremenko
Date: 2012 Apr 4, 17:32 -0400
From: Alexandre Eremenko
Date: 2012 Apr 4, 17:32 -0400
Ken, Yes, it looks exactly as the Soviet model, as far as I can judge from those tiny pictures:-) I am still surprized: is there really any substantial demand for this heavy and expensive toy, I mean demand that is not covered by e-Bay? Why else would they make it? You can certainly solve the same problem will all precision needed for practical navigation with a simple plastic station pointer you always had, or with a simple computer program. Besides, there is no place to store this thing in a small boat:-) Alex. On Wed, 4 Apr 2012, Ken Gebhart wrote: > > Alex, > > Yes it is made by the same factory, and possibly is a copy of the > Russian model. Your comment is certainly correct, and we are > replacing "determine the direction" with "identifies". As for the > two solutions, we didn't want to confuse the reader, or start a new > dialog about the math. Thanks for your comments. > > Ken > On Apr 4, 2012, at 12:56 PM, Alexandre E Eremenko wrote: > >> >> Indeed! >> >> I am surprized. They do not say who makes them, >> Ken, is it by the Astra factory? >> The construction seems exactly the same as of the Soviet one >> that I have, except that the Soviet one is made entirely of bronze, >> and this one of an aluminium alloy. >> The box is of slightly different construction. >> (Soviet ones on e-bay usually cost a bit less). >> >> There are several imprecise points in the Celestaire description. >> >> a) You do not need to measure the DIRECTIONS (bearings) of 3 objects >> but only TWO HORIZONTAL ANGLES between them. This is done with >> a sextant. (A direction is measured with a compass, and it is >> hard, if not at all impossibe to measure with 1' accuracy). >> >> b) "There is only one solution". There are generally 2 solutions. >> The are usually far apart, if one takes the right objects to >> measure angles between them, and one of the solutions is usually on >> land. >> Geometrically, these solutions are the points of intersection >> of two circles (position lines). Two circles usually intersect at 2 >> points. >> >> Alex. >> >> >> > > > > > > : http://fer3.com/arc/m2.aspx?i=118702 > > >