Displaying historical layline data
As True Wind Direction (TWD) is constantly
changing, the position of the Laylines change over
time. These changes are shown as lighter colored
shaded triangles which represent the minimum and
maximum TWD over the a specied time period.
Tip In the Diagram below:
• With TWD holding at its Maximum value the vessel
can Tack to starboard and will lay the waypoint as
it enters the shaded area. However if TWD shifts
back towards its Minimum value the vessel will fall
short of the layline and may have to perform extra
Tacks to reach the waypoint.
• With TWD holding at its Minimum value the
vessel can Tack to starboard and will only lay the
waypoint when it reaches the end of the shaded
area. However if TWD shifts back towards its
Maximum value the vessel will overlay and may
travel farther to reach the waypoint.
• Depending on the situation , the normal course of
action would be to Tack when the vessel is halfway
through the shaded area. However this may not
be the shortest or quickest method.
To display historical layline data:
1. Select Laylines Set-up from the Laylines menu.
2. Select Min & Max Laylines:.
3. Select the time period that you want the historical
data to cover.
Historical Laylines can be reset at any time by
selecting Reset Min & Max Laylines from the
Laylines Set-up menu.
14.19 Polar tables
Polar coordinate tables for your vessel can be
imported in .csv format. The layout of the .csv le
must adhere to the layout detailed below.
Spreadsheet programs such as Microsoft Excel can
be used to .csv les.
The following table layout constraints apply:
Column 1
• The rst cell is ignored
• Column 1 must contain the relevant TWA angles
• A minimum of 3 TWA angles are required
Rows
• The rst cell is ignored
• Row 1 must contain the relevant TWS values in
knots
• A minimum of 3 TWS values are required
Example table layout
1. Increasing TWS values in knots
2. Increasing TWA values in degrees
3. Target vessel speed values in knots
Importing a polar table
Once the polar table has been created and saved as
a .csv le it can be imported into the MFD using a
MicroSD card.
With the MicroSD card containing the .csv le
inserted into your MFDs card reader:
From the Chart application’s Laylines set-up menu:
Menu > Presentation > Vectors > Laylines Set-up.
1. Select Import Polar Table.
2. Browse to the location of the .csv le on your
MicroSD card and select it.
The polar table has now been imported and the
Polars option will be available from the Laylines
Type menu.
Note: The Polar table can be deleted from the
system at any time by selecting Delete Polar table
from the Laylines Set-up menu.
Chart application
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