|Main new feature of this version is a graph dedicated to apparent wind (force and direction).|
As you may know, the wind you feel on a boat is the vectorial sum (combination) of the speed wind and the real wind.
speed wind is what you feel when you're riding a bike (with no real
wind) : air going in your face, and which is facing you. It speeds is
equals to your speed.
In GpsarPro 4.18 and above, you can choose
a new "Apparent Wind" graph in one of the windows (click "change view"
to selected it in the top-right corner of the choosen window).
you see a diagram showing a boat oriented toward the top of the screen.
For each track, at any moment, comes a vector figuring apparent wind,
composed of the speed wind (vertically aligned, and finishing with a
dotted rectangle), and of the real wind.
To have correct values, you have to set :
the correct wind direction. In many case, it is automatically computed
at the correct value when loading a track. If not, you can click on the
weathervane to set it at the correct direction
- the (average) wind force, directly in the bottom-left of the apparent wind graph (via a slider)
Here are some examples of what we get :
speed run with deep downind angle, but still resulting in apparent wind
facing the windsurfer (note that in this case, the apparent wind force
is only about 20 knots instead of 25 knots real wind speed) :
The same with a different setting of the wind force (30 knots instead of 25) :
course, what is provided with this new feature is only as accurate as
wind direction and wind force are correctly adjusted. And as everybody
knows, wind changes through time, in force as well as in direction...
However, this provides a good idea of what happens, and is intersting
in a didactic point of view.