Polar Data for Beneteau 35.7
How to read the polar chart:
The radial lines represent the angles of the boat with respect to the True Wind. The heavy lines labeled ‘4n’, ‘8n’, … are constant
True Wind Speeds. The arcs of increasing radius represent the target boat speeds.
For Example: If the wind is coming from 270 and the boat is headed 150 then the True Wind angle is 120. Ignore the sign of the
True Wind angle since the plot is symmetric. If the True Wind Speed is 8 knots read the point where the ‘8n’ line crosses the 120
radial and read off the target speed. It is approximately 6 ½ knots.
The optimal velocity downwind for a given True Wind Speed is the lowest point on the Wind Speed curve. For example, in 8 knots
of wind, the fastest downwind sailing angle is a True Wind Angle of 143. This means we should jibe though 74 (2x(180-143)=74).
The target speed at this condition is about 5.5 knots. The effective velocity to the downwind mark is 4.4 knots (5.5xcos(180-
143)=4.4) which is faster than the 4.0 knots we would achieve going dead downwind. The Apparent Wind Angle (which can be read
off the Downwind Jibing Angle chart) at this point will be much smaller (wind coming closer to the front of the boat) than the 143 of
the True Wind Angle.