Specification Of A Pair Of Waypoints ("From'' & "To") (Nav Mode); Range And Bearing Calculations (R/B And Clc Modes) - Furuno LC-90 Owner's Manual

If you would like to confirm the coordinates of each waypoint, call up the
WPT Mode and enter the waypoint number desired. If the waypoint has
been specified by TD's you may hit the I TD <-> L/L I key to see the TD's.
Make sure that you hit the | TD «-»L/L I key again to get back into the L/L
format.
Specification of a Pair of Waypoints ("From"/"To" Waypoints) (NAV Mode):
Now let's try selecting a pair of waypoints. This is done whenever you
want to use Cross-Track Error or go between two waypoints. This is also
needed when you wish to specify a line defining the Border of a particular
zone whieh you want to avoid. Both Cross-Track Error (XTE) and Border
alarms will be described in detail later on in this section.
Let' s say that you want to set up a voyage between waypoints 55 and 56.
You would make sure that you are in the NAV mode by moving the left or
right arrow key s to line up the Mode indicator dir eetly over the "NAV"
label on the front panel under the display. .As usual, the cursor will have
automatically placed itself at the first point at which data may be entered,
on the third line. You would key in:
1 CLR I PT| [Ud]® fENT | From waypoint 55 To waypoint 56.
The display will show the starting waypoint "55" on the left-hand side,
with an arrow pointing to the right towards the destination waypoint "56."
You can now go to another funetion which uses waypoints, since you have
specified the waypoints of interest.
RANGE AND BEARING CALCULATIONS (R/B and CLC Modes)
To steer to a waypoint, you would like to have two pieces of information:
the direction in which to steer, and the distance to the waypoint. The
LC-90 provides two forms of Range/Bearing calculations to aid you in
navigating to a waypbint or in navigating from waypoint to waypoint:
a. Simple Range/Bearing from Present Position to a waypoint (R/B Mode).
b. Range/Bearing from waypoint to waypoint (CLC Mode).
Simple Range and Bearing from Present Position to a Waypoint (R/B Mode):
The range and the bearing from present position is the most basic
information you can use to navigate to a waypoint. You have learned how to
select a destination waypoint in the NAV mode in the section above. Now,
solect the R/B Mode by moving the Mode indicator with the left or right
arrow keys until is it lined up direetly over the "R/B" Mode label. The
range and bearing from your present position to the waypoint selected in
the NAV Mode (calculated on the basis of a Great Circle course) will be
displayed on the bottom two lines in the R/B display. The range is in
nautical miles and the bearing is normally Magnetic. If the indication
"MAGV" doesn't appear at the top right of the display, this indicates that
you have manually set "60" as a variation, and that the bearing is thus
relative to True North.
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Fig. 21 shows a typical R/B display.
.In the process of planning a voyage, a series of waypoints is usually selected
in advance, and a Range/Bearing calc ula tion is made to get the heading to
use for the first leg of the voyage. As you approach the first waypoint, you
then will want to calculate in advance the next heading to take in order to
get to the second waypoint after you round the first one. To do this you
will need to use the CLC Mode in the LC-90.
The procedure is straightforward. In this Mode you needn't respecify the
waypoints presently being used by using the NAV Mode. Instead, you may
make this calculation "offline" (to use some computer jargon) without affeeting
normal operations of the LC-90, which may have been navigating between two
waypoints already previously selected in the NAV Mode. You wouldnTt want
to change the present voyage parameters in order to do a planning
calculation. Let's say that you are presently traveling from waypoint 56 to
57 (selected in the NAV Mode), and that you want to determine in advance
the heading to set into your autopilot after you round waypoint 57 on the
way to the next waypoint 58.
1. First, get into the CLC Mode, using as usual the left or right arrow keys
to line up the Mode indicator arrow over the "CLC" label. The cursor will
automatically place itself on the third line.
2. Now key in the following:
LCLR 1 Em®® I ENT | From waypoint 57 to 58.
You will now see the Range and Bearing for the voyage from waypoint 57
to waypoint 58 displayed on the fourth and fifth lines respectively.
See the figure below for a typical display screen.
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