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Marc St Hilaire Method: For Finding A Ship's Position at Sea (1919)
Fritz E. Uttmark
No preview available - 2009
24 hours 50 Uttmark's A. M. Chron altitude of sun's Answer.—Lat Arcturus Astr azimuth line bearing East bearing West Bowditch Chro Chronom Chronometer slow lm compass diagram compass rose Corr creasing D. R. position Dead Reckoning Diamond Shoal Diff draw the second draw the Sumner Equation eye 40 feet Finding a Ship's G. M. T. Noon heavenly bodies Height of eye Hilaire Method intercept and draw intersection June 28 lines on Uttmark's Long Marc St meridian Nautical Almanac North P. M. Chronometer slow point draw Pole star Position at Sea position at second position by D. R. position of ship Problem Required position right ascension Rules for plotting second observation second sight sextant ship in Lat ship then sailed ship's true SIMULTANEOUS OBSERVATIONS slow lm 19s Sun's decl sun's lower limb take out log True azimuth U. S. Hydrographic Office Uttmark's Plotting Chart Vega westerly hour angle
Page 4 - This enables obtaining latitude by the meridian observation and the ship's position by intersection of the Sumner lines. When the sun alone is visible it is necessary to make two observations with an interval of time. The point of intersection of two Sumner lines may be found by computation or by plotting on the chart, the latter being by far the more simple. Specially designed charts for plotting have the inconvenience, however, of being bulky; for example, to cover the latitude from the equator...
Page 4 - ... the former charts, and is therefore 50 per cent more efficient than the scale on the plotting chart published by the US Hydrographic Office. Captain Uttmark's chart may be used for plotting ship's position by any method using the Sumner lines.
Page 7 - ... Find the longitude at the time of taking the first observation using the latitude by account, and take from the tables the Azimuth corresponding to the hour angle found in the computation. On the chart lay down the position of the point given by the latitude by account and the longitude found. From this point draw a line in the direction of the Azimuth, then a line drawn through the point at right angles to the direction of the Azimuth is the first line of position. Find the longitude at the...