Self Assessment 9
§ 32 – 36
This Self Assessment covers § 01 – 36, descriptive answers should be as full and detailed as possible. Where appropriate use the ANC Extracts from the N.A. and Sight Reduction Tables for Marine Navigation N.P. 401 (H.D.605) Vol. 4. Question 12 should be worked on the ANC Sight Form and Astro Plotting Sheet
115. List the day-to-day routine and responsibilities of a small-craft navigator when at sea on a long-distance passage, inc the navigational records for which he is responsible.
116. Outline the practical procedures involved in preparing for taking and timing sights, including the averaging of sights for reduction.
117. Differentiate between a blunder, a systematic error and a random error in Astro navigation and state how each may be avoided or detected.
118. The navigator of a craft proceeding up the English Channel out of sight of land on a Course of 050ºT. wishes to check her progress during the morning of Jul 04th 199X in D.R. Lat. 50º 03.0 N., Long. 002º 07.0 W. In both cases state the approximate Alt. of the observed body at the time given.
a. At what time should he observe the Moon for this purpose?
b. At what time should he observe the Sun for a track check?
119. A vessel voyaging in areas where she has difficulty obtaining radio time signals carries both a Chronometer and a Deck Watch as a safeguard. The Chronometer is 03m. 30s. fast on the Deck Watch on May 01st at 12:00 G.M.T., and on Jul 04th the Chronometer was 00m. 14s. fast on the Deck Watch at 12:00 G.M.T.. If the daily rate of the Chronometer was 1.5 seconds gaining., what was the daily rate of the Deck Watch?
120. A vessel in D. R. Lat. 00º 12.0 N., Long. 80º 29.0 W. obtained a meridian altitude of The Moon at 15:44 (Zone + 5) on Jan 21st 199X in which the Sext. Alt. of the Moon’s upper limb was found to be 65º 04.5 bearing S., I.E. + 0.5, H. of. E. 12ft. Find the G.M.T.. of Mer. Pass. and the vessel’s Lat., illustrating the problem with a figure on the equidistant projection.
121. Using the planetary information on page XXXX of Lesson 7, determine: –
a. The approximate S.H.A. and L.M.T. of Mer. Pass. of Venus ♀on Aug 10th 199X, and whether Venus ♀is observable at this time.
b. The position of Jupiter♃in the sky during morning twilight on Nov 01st 199X and the approximate L.M.T. of Jupiter’s Mer. Pass. on the same day.
c. The approximate L.M.T. of Mer. Pass. of Alpheratz on Jun 10th 199X.
122. Find the Zone Times of Civil twilight for the morning and evening of Jul 03rd 199X in Lat. 56º 42.0 N, Long. 19º 45.0 E.
123. On Jul 04th 199X in D.R. Lat. 34º 02.0 N., Long. 029º 57.0 E. the D.W.T. wasO2h.10m.05s. when the Sext. Alt. of ✴︎ Polaris was 34º 35.4. I.E. –0.5, H of E. 9ft. D.W.E.42s. slow on G.M.T.. Find the vessel’s Lat..
a. At the same time as the Sext. Alt. in (121.) above, the compass bearing of Polaris was observed to be 355º C.
b. Find the compass error and Dev. for the vessel’s heading if the Variation in this locality is 1¾º E.
124. At 04:47 (Zone -10) on Jan 02nd 199X in Lat. 45º 12.0 S., Long. 152º 21.0 E. a Compass bearing of Procyon gave 285º C, when the D.W.T read 18h. 46m. 55s (correct on G.M.T.). Find the compass error and Dev. for the vessel’s heading if the Variation in this locality is 15º E.
125. On Jan 20th 199X in Lat.13º 57.0 N., Long. 072º 08.0 W. the compass bearing of theSun at true sunrise was 113º C. Find the compass error and Dev. if the Var. is 5º W.
126. At 1708 (Zone +1) on Jul 04th 199X in D.R. Lat. 45º 57.0 N., Long. 014º 38.0 W. the Sext. Alt. of JUPITER ♃ was 45º 52.7 at D.W.T. 18h. 09m. 47s. The sextant used has an I.E. of 2.2 off the arc the Deck Watch was 01m. 05s. fast on G.M.T. and the observer’s H. of. E. was 13ft.
127. The vessel then made good a course of 030º T. at 8 knots until evening twilight when the following stellar observations were taken.
✴︎DENEBOLA D.W.T. 21h. 11m. 30s. Sext. Alt. 38º 38.1
✴︎RASALHAGUE D.W.T. 21h. 13m. 00s. Sext. Alt. 44º 03.1
Find the vessel’s D.R. Position. at 20:12 (Zone + l) & The vessel’s Observed Position at 20:12 (Zone + l)