2 longitude error table (on 96 nm range scale) – Furuno RP-250 User Manual
Page 34
6. OTHER PLOTTER FUNCTIONS
28
6.2
Longitude Error Table (on 96 nm range 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 error,
represented from 0
°
to 90
°
at 96 nm from the radar center (own ship).
62
°
N
°
N
60
°
N
135
°
E
139
°
E
Real cursor position
Cursor position
indicated
LAT
E
Real cursor position
Cursor position
indicated
96 nm
θ
OS position
R: Error
Distance error in direction of longitude due to latitude