In the Marcq St Hilaire method, a calculated zenith distance or altitude is compared with the observed zenith distance or altitude to obtain an intercept which is plotted from a DR position in the direction of the body’s true bearing. In explaining this method, the altitude and not the zenith distance will be used. The…
During the discussion of the celestial sphere last year, we discussed the spherical triangle PZX which was formed by the projected positions of the celestial pole (P), the observer’s zenith (Z) and the celestial body (X), on the celestial sphere. It was stated that the solution of this triangle formed the basis of all astronomical…
This website has been compiled for the guidance of and use by grade 12 learners taking Nautical Science as one of their secondary school subjects. It follows the approved national curriculum for the subject and comprises three parts, namely Navigation, Seamanship and Communications Metereology is covered on Grades 10 & 11). Although it has been…
When we refer to plane sailing we mean sailing from one position to another where the latitude and longitude of each is different to the other. Because we are using a mean latitude, this method is not very accurate over long distances and should be confined to distances of 600 nautical miles or less. To…