Furuno DD-80 - Manual (Page 45)

5 – 7
5.4 Finding Range and
Bearing Between Two Points
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.
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
Figure 5-19 MANUAL
CALCULATION menu
2) Choose two points by one 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 (000-
999). (000 is reserved for own ship
position.)
2) Press ▼ twice.
3) Key in other waypoint number (000-
999).
3) Press ▼ to shift the cursor to the Trial
Speed line.
4) Press t or s to select Auto or Man.
Auto uses ship's average speed to calcu-
late time-to-go.
5) If you selected Man, enter speed.
6) Press the [NU/CU ENT] key.
The range, bearing and time-to-go between
two points appear on the display. If data en-
tered is wrong or insufficient the buzzer
sounds and the message "INCOMPLETE
DATA" appears. If the data contains error, "*"
and all nines appear as the calculation results.
7) Press the [MENU ESC] key.
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.