Raymarine Marine GPS System - Manual (Page 150)

Advanced Navigator Functions
5-59
How to Graph and Read a Polar Plot
This section lists the basic steps you must perform to graph and read a
Polar Plot screen (Figures 5-14 and 5-18). The Polar Plot screen
graphs the theoretical headings your boat should take toward specified
targets (both upwind and down) when encountering various wind
conditions. As discussed earlier, the accuracy of these graphs depends
primarily on the volume and accuracy of the boat- and weather-
specific information you’ve entered into the Polar Parameters and
Data Tests screens. After you have entered your data, that information
is displayed as a polar graph in the Polar Plot screen. Placing the
cursor anywhere along the Polar plot yields a small pop-up window
that displays the wind angle/boat speed correlation at that point.
To graph a Polar plot, do the following:
1. Enter all requisite data into the Polar Parameters and Data
Test screens as described in the previous subsections.
2. Click the Polar tab to display the Polar Plot Screen.
3. As shown in Figure 5-18, select the boat speed scale (bottom
axis) you want displayed by clicking on the Boatspeed (kts)
up/down arrows or by entering numbers directly.
4. Select the range of True Wind Speeds to be plotted by
clicking on the Tws (kts) up/down arrows or by entering
numbers directly.