Which samples go into the heel curves and the speed-by-angle chart, and what they can and cannot tell you.
Heel
Upwind samples faster than 2.5 kn and at least 20 s clear of turns are compared with the fleet’s median VMG in the same race minute, then grouped by heel. A fleet bin needs 30 samples and a boat’s 150, so a few gusty minutes cannot draw a curve.
More breeze brings more heel and more VMG at once, so the curve describes how this regatta went at each heel angle. It is not a target to sail to.
Speed by angle
The polar uses samples faster than 1 kn and at least 15 s clear of turns on every leg, binned by the angle to the course axis. A fleet bin needs 400 samples and a boat’s 100. Speeds are over the ground, so current and leeway are in them.
The figures, one by one
VMG by heel
Upwind samples faster than 2.5 kn and at least 20 s clear of turns, each against the fleet’s median in the same minute (a minute needs 20 fleet samples). A bin is drawn with 30 samples for the fleet and 150 for a boat. Wind strength drives both heel and VMG, so this is a description of the regatta, not a heel target.
Unit
% of the fleet’s median VMG in the same race minute, by heel bin
Reading it
Above 100 is better VMG than the fleet in that minute.
Scope
Pooled over the selected races; upwind steady samples only.
Rules this figure depends on, read from the analysis code
Speed over the ground by the angle between course and the course axis, from samples faster than 1 kn and at least 15 s clear of turns. A bin is drawn with 400 samples for the fleet and 100 for a boat. It includes current and leeway and is not a wind-referenced polar.
Unit
knots over the ground by angle to the course axis
Scope
Pooled over the selected races; median and 90th percentile per bin.
Rules this figure depends on, read from the analysis code