Furuno BACK GP-80 - Manual (Page 43)

5 – 7
Calculation Procedure
You can find the range and bearing between
two points by two waypoints or two latitude
and longitude positions.
1) Press [MENU ESC] and [5]. The
MANUAL CALCULATION menu ap-
pears.
Figure 5-20 MANUAL
CALCULATION menu
2) Choose two points by one of the methods
below.
Latitude and longitude positions
1) Press ▼.
2) If necessary press to switch from
North latitude and to South latitude
vice versa.
3) Key in latitude.
4) If necessary press to switch from West
longitude to East longitude and vice
versa.
5) Key in longitude.
6) Press ▼.
7) Repeat 2-5 to enter other point.
Waypoints
1) Key in first waypoint number (001-
999). (000 is reserved for own ship
position.)
2) Press ▼ twice.
3) Key in other waypoint number (001-
999).
(Continued on next page)
5.4 Finding Range and
Bearing Between Two Points
Selecting Course Sailing Method
The range and bearing to a destination are cal-
culated by two ways: Great Circle or Rhumb
Line. However, cross track error is calculated
by rhumb line only.
Great Circle: The great circle courseline is
the shortest course between two points on the
surface of the earth. (Imagine stretching a
piece of yarn between two points on the earth.)
However, this course requires frequent change
of heading to follow course faithfully.
Rhumb Line: The rhumb line courseline is
the straight line drawn between two points on
a nautical chart. This course does not require
frequent changes of heading however it is not
the shortest since it follows the earth's curva-
ture.
1) Press [MENU ESC] [9] and [1] to dis-
play the PLOTTER SETUP menu.
Figure 5-19 PLOTTER SETUP menu
2) Press ▲ or ▼ to selection Calculation.
3) Press t or s to select R.L (Rhumb Line)
or G.C (Great Circle).
4) Press the [NU/CU ENT] key.
5) Press the [MENU ESC] key.
MANUAL CALCULATION
: N/S, E/W ENT : Calculation
: Cursor MENU : Escape
From Waypoint No.
. ’N . ’E
To Waypoint No.
. ’N . ’E
Trial speed : Auto Man
( . kt)
Rng : . m Brg : .
TTG : D H M
PLOTTER SETUP
Bearing Ref.
Auto
(07° W)
Man
(00° E)
ENT:Enter MENU:Escape
Memory Apportion
Mag Variation
True
Trk = 1000 / 2000Pt
Mag
R.L G.C Calculation
User defined #1 SPD
User defined #2 CRS
User defined #3 RNG
User defined #4 BRG