B&G Deckman - Manual (Page 100)

Understanding Polars
6.1
Chapter 6 : Polars
Understanding Polars
Below is an example of the polars window (Figure 6.1). On the left is
the table where the values are entered, on the right is the polar plot—the
distance from the centre shows the boat speed at a wind angle specified
relative to the vertical. Imagine the wind blowing down from the top of
the page—the boat speed in 12 knots of wind for each of the five wind
angles is indicated by the small solid squares.
Polars in Deckman are described in a special way: at several wind
speeds (which are adjustable) the curve of boat speed versus true wind
angle is defined by just five points. Although this may be thought to be
too few to be accurate the mathematical functions work very well in
practice. It is important when sailing that the polars can be adjusted
quickly and easily and still remain fair—with so few points this is
Figure 6.1