NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Equal altitudes at noon
From: Mal Misuraca
Date: 1997 Feb 14, 10:03 EST
From: Mal Misuraca
Date: 1997 Feb 14, 10:03 EST
position seems beside the point. When the great majority of sailors are abandoning celestial for GPS, and thus risking themselves without a non-electronic means to navigate, we are unwise to devote so much time to whether precise fixes can be obtained with celestial. That plays the GPS game, and GPS accuracy is irrelevant in most cases to sea navigation. Landfall is the spot in the ocean where the navigator can switch back to coastal navigation. It may be as much as 30 or more miles off land, depending on when the terrain features allow coastal to be substituted for celestial. At 30 miles off, some rate of error is obviously permissible, more than enough to be covered by the debate we have had here. (Low-lying terrain calls for closer landfalls, and these demand more vigilance and assume a crew well attuned to the needs of safety.) In this context, the argument over equal altitudes versus lines of position seems to me entirely academic. Sights taken close enough together to yield equal altitudes will not satisfy the navigator who tries to use them to establish intersecting lines of position; the "cuts" will not be good. The same room for error based on erroneous courses, distances, leeway, and so on will infect equal altitudes and running fixes. The simple fact is, from my experience teaching many modern sailors, that many will not take time to master the use of sight reduction tables, assumed positions, and local hour angles, whereas they will take avidly to equal altitudes and the symmetry of the rise and fall of the sun around local apparent noon. If that gets them safely to landfall when their GPS goes south on them, why are we spending so much time being shocked, shocked to learn that equal altitudes are being resorted to in this establishment? Mal Misuraca "Celestial in a Day" celestial_mam@XXX.XXX KO6KR, "Passage East" Sausalito