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Northstar Explorer 657 Installation and Operation Manual62
Press twice, then select Chart:
Rotation
The options for chart rotation are:
North up: North is always at the top of the
chart window.
Track up: The chart is rotated so that the
boat direction is to the top of the display.
This option is useful for navigating narrow
harbours or rivers. The 657 asks for a course
deviation resolution; this is how much the
boat direction needs to change to make the
chart redraw.
Tip: If the chart redraws too
frequently, increase the course deviation
setting.
17-2 Setup > Chart
Course up: This option is only available
if the boat is navigating to a destination. The
chart is rotated so that the plotted course to
the destination is vertical.
Palette
Select the color scheme for the LCD display.
The options are:
Normal
Sunlight: Brighter colors, more visible in
sunlight.
Night: Reversed colors for night, to preserve
night vision.
Map datum
657 GPS positions are based on a worldwide
reference (datum) known as WGS 84. Most paper
charts are based on WGS 84. However, some
paper charts are based on other datums In these
cases, the latitude and longitude coordinates of
objects on the 657 chart window are different
to the latitude and longitude coordinates of
these objects on the paper chart. This applies to
all objects, such as the boat, waypoints, tracks,
lines of latitude and longitude and cartographic
features such as land, rocks, buoys and depth
contours.
Use Map datum to select the 657 map datum
to match the datum of the paper chart. Then, the
latitude and longitude coordinates of objects
displayed on the 657 will change to match the
corresponding coordinates on the paper chart.
Setting map datum
1 In the Chart setup menu, select Map
datum.
2 Select the map datum for the paper chart you
are using.
3 If you select a datum other than WGS 84
the 657 asks if you want to apply the NMEA
datum offset (see below).
!
WARNING
When you change to a chart with a different
datum, change the 657 map datum again.