Appendix 2 Longitude Error Table (96 Nm Scale - Furuno FAR-2218-BB Operator's Manual

APPENDIX 2 LONGITUDE ERROR TA-
BLE (96 NM SCALE)
The longitude lines concentrate on the north pole and south pole, namely, 1 nm is equivalent to 1
minute at 0 degree latitude, 2 minutes at 60 degrees latitude, 3 minutes at 70 degrees latitude and
so on. For this reason, a longitude error occurs on the radar display.
For example, when own ship is at 60°N and 135°E, even if the cursor indication is 62°N and 139°E,
the real cursor position is deviated to the left (west) side. The table below shows the longitude er-
ror, represented from 0° to 90° at 96 nm from the radar center (own ship).
Real cursor position
62°N
60°N
135°E
q
°
5 10
LAT
75° 0.2256 0.4444
0.21980213 0.43290201 0.632803
70°
0.21229339 0.41810678 0.61115946 0.78556318 0.93600295 1.05790007 1.14755221 1.20224625 1.22034042
65°
60° 0.20316898 0.40012949 0.58486463 0.75173456 0.89565021 1.0122297
0.19249832 0.37910698 0.55411863 0.71218478 0.84848102 0.95885565 1.03998717 1.08933651 1.10552105
55°
0.18036264 0.35519924 0.51915545 0.66721485 0.79485438 0.89818413 0.97406698 1.02021439 1.03525547
50°
45° 0.16685429 0.32858822 0.48024119 0.61716701 0.73517843 0.83067689 0.90076355 0.94332783 0.95711098
40° 0.15207608 0.29947644 0.437672
35° 0.13614047 0.26808546 0.39177186 0.53339693 0.59953781 0.67725844 0.73420069 0.76865661 0.77961957
30° 0.11916876 0.2346542
25° 0.10129001 0.19943707 0.29139874 0.37433139 0.44568053 0.50326182 0.54532952 0.57063015 0.57843983
20° 0.08264056 0.16270211 0.23768966 0.30527334 0.36336372 0.41017869 0.44429984 0.46471615 0.47085389
15° 0.06336208 0.12472888 0.18217162 0.23389198 0.27828148 0.31397386 0.33988878 0.35526538 0.35968447
10°
0.04360137 0.0858064
5° 0.02350833 0.04623087 0.0674093
0° 0.00323737 0.0063035
AP-8
Cursor position
indicated
139°E
° ° °
15 20
0.6496 0.8350
0.8134132
0.56242216 0.66990732 0.7568477
0.3428901 0.44054055 0.52460545 0.59251483 0.6422089
0.12526714 0.16073056 0.19108136 0.21537949 0.23289096 0.24311083 0.24577764
0.08634588 0.10242699 0.11514595 0.1241207
0.00903844 0.01130406 0.01299309 0.01403609 0.0144058
Real cursor position
°N
96 nm
q
LAT
OS position
° °
25 30
0.9950 1.1248 1.2202
0.96923215 1.09551918 1.1884382
1.09793265 1.15016811 1.16737294
0.82060477 0.85926197 0.87168229
R: Error
Cursor position
indicated
°E
° °
35 40 45
1.2786 1.2980
1.24517456 1.26402037
0.67220131 0.68162348
0.12910605 0.13000029
0.0141187 0.01323356
(nm)
°