VERTICAL SEXTANT ANGLES SHORT OF THE HORIZON

W. C. Marlow

Peer Reviewed

Abstract: A proof is given that the effects of the height of the eye, earth curvature, and atmospheric refraction can be safely ignored when vertical sextant angle measurements short of the horizon are used in practical navigation problems. The expression D tan(hs) = H, relating the distance-off, sextant altitude, and navigation aid height, is shown to provide satisfactory accuracy for safe navigation where dip short of the horizon techniques are applicable. The double table entry procedure suggested in Bowditch for vertical sextant angle calculations is shown to be unnecessary and is incorrect with respect to the prediction of the effects of both earth curvature and atmospheric refraction.
Published in: NAVIGATION, Journal of the Institute of Navigation, Volume 28, Number 1
Pages: 55 - 64
Cite this article: Marlow, W. C., "VERTICAL SEXTANT ANGLES SHORT OF THE HORIZON", NAVIGATION, Journal of The Institute of Navigation, Vol. 28, No. 1, Spring 1981, pp. 55-64.
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