There are two kinds of polars...those calculated by the naval architect as target boat speeds, and those developed off of real-world data. For the most part, the delta
between the two is a function of lading, sail condition, sea state blah blah blah.
One line is for one set of sails
. Polars usually have a different set of data points and line for the kite.
And yeah, that bump at 100 degrees is weird. All I can think is that it's where enough of a hull
came up that there was a jump up in speed.
If you want to create polars for your existing boat, there is an app for that
You input TWS and course off the wind
and app logs
the data through GPS
and creates the diagram.
Honestly, most polars for a given type of boat look pretty much the same, and unless you're racing
are kinda more trouble than they are worth other than eyeballing them and going "yep, it's as I suspected."
It's worth pointing out that the greatest value in them is in determining your best point of sail for VMG beating to windward. It's the highest point of arc
of plot line, so in the case of the FP 46, it's 50 degrees.