Nav 4 – Compass Error Calculation

CAPT. MANALO , M.E BSMT NAV 4 – COMPASS ERROR CALCULATION GYRO ERROR by AMPLITITUDE of the Sun Example: Decl. = d corr = Decl = S 11° 50.5 0.5 S 11° 50.0’ 5. Solve for the value of Amplitude: On Feb. 17, 2025, @ 1735 Lt, in Position Latitude: 13° 45' 36'' N / Longitude: 121° 03' 00'' E, the ships on Gyro Course 315°, and Magnetic Compass heading of 318°, the OOW took a sunset observation of the sun Gyro bearing of the sun was 258 ᵒ T. Determine the gyro error by amplitude if the variation of the area is 1ᵒE. Sin Amplitude = Sin Dec Cos Lat Amplitude = Sin-1 ( sin 11° 50.0’/ Cos 13° 45' 36'') = Sin-1 (0.20507 / 0.97130) Amp = S 12.2° W To solve for Amplitude you will need: To get the Azimuth (ZN or True Bearing) do the operation as per the following quadrants: N UTC Gyro Bearing Latitude Declination + 270 -90 1.Solve for UTC W Local Time = 1735 ZD (-E) = 8 GMT = 0935H E -270 + 90 2.Get the value of declination from the nautical almanac corresponding to the date and the whole number of time of GMT. Take note also of the value of “d” at the bottom left of the table. Azimuth (Zn) (Zn) UT 09 HOW TO SOLVE GYRO ERROR: DECLINATION: S 11°50.5’ “d” 0.9’ 3. Get the value of the correction corresponding to “d” from the “Increments and correction table” of the nautical almanac. Locate first the minutes of GMT. At the column “v and d” correction, find the value corresponding to “d”. UT 0935 “d” 0.9’ v and d correction 0.5’ 4. Based on whether the declination is ascending or descending, add or subtract the v and d correction. (based on the given example, declination is descending, so we subtract.) NAVIGATION 4 = = 270 - 12.2° 257.8 T True Bearing Gyro Bearing Gyro Error Gyro Course True Course Magnetic Course Magnetic Error Variation Deviation CELESTIAL NAVIGATION CAPT. MANALO , M.E BSMT NAV 4 – COMPASS ERROR CALCULATION TB = GB = GE = GC = TC = MC = ME = 257.8 258 0.2 W 315 315.2 318 2.8 W Var = 1 E (W) Dev = 3.8 W Always Subtract the smaller value from the bigger value Name the gyro error by : compass Best error WEST / compass least error EAST Apply gyro error to the gyro course ( East plus(add) / West minus (subtract) to get the True Course. Always Subtract the smaller value from the bigger value (TC and MC) Name the compass error by : compass Best error WEST / compass least error EAST (Reverse the name of variation then: if same name with ME add Var, if different name with ME subtract Var Takes the name of the higher Value CHECKING C D M V T = = = = = 318 3.8 W 314.2 1E 315. 2 NAVIGATION 4 “C” = Magnetic Compass Course “D” = Deviation (East plus / West minus from “C”) “M” = Corrected compass heading “V” = Variation (Use the original name then EAST plus / WEST minus) “T” = True Course (This should be the same value with the TC (true course) above. If it is not the same, something wrong my frend.) CELESTIAL NAVIGATION CAPT. MANALO , M.E BSMT NAV 4 – COMPASS ERROR CALCULATION NAVIGATION 4 CELESTIAL NAVIGATION CAPT. MANALO , M.E BSMT NAV 4 – COMPASS ERROR CALCULATION NAVIGATION 4 CELESTIAL NAVIGATION CAPT. MANALO , M.E BSMT NAV 4 – COMPASS ERROR CALCULATION NAVIGATION 4 CELESTIAL NAVIGATION