NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sextant accuracies - coastal piloting
From: Rodney Myrvaagnes
Date: 2003 Mar 18, 09:07 -0500
From: Rodney Myrvaagnes
Date: 2003 Mar 18, 09:07 -0500
On Mon, 17 Mar 2003 23:05:20 -0500, Arthur Pearson wrote: > >I take this to mean I can measure the "altitude" of Mt. Desert Island >from the summit to the visible horizon while the bulk of the island is >still below the horizon and get a distance off. You don't need to see >the bottom of the object to get a distance off by vertical angle. >Bowditch provides the formula which I have plugged into my palm pilot >for quick use. > I stand corrected. The geometry is certainly correct. It does have the same problems of refraction that celestial sights at low altitudes exhibit. Without trying numbers, My intuition says that the first sight of Isle au Haut would give you a horizontal angle of much greater use. The charts do have contours that locate the summits pretty well. I appreciate Arthur's choice of MDI as example. It is a landfall I have made many times, and this gives me another thing to think about and try out in September. Rodney Myrvaagnes NYC J36 Gjo/a "Be careful. The toe you stepped on yesterday may be connected to the ass you have to kiss today." --Former mayor Ciancia
