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Fleet research

Method notes

The rules behind each figure on the fleet pages, with the thresholds the analysis uses.

  • Whole-leg VMG and steady-sailing VMG

    How the pages separate what a boat gained over a whole leg from how it sailed when it was simply going in a straight line beside other boats.

    Whole-leg VMG index · Steady VMG index, local wind · Steady VMG index, course axis · Speed and direction efficiency · Matched coverage · Direction sensitivity · Wind-neighbourhood sensitivity · Speed and height

  • Local wind from the fleet’s own tracks

    How a ground-referenced wind direction is inferred from boats on opposite tacks, and why the boat being scored never contributes to its own estimate.

    Local wind direction · Gybe-based wind share

  • Time budget, leg gains and what decided it

    Where a boat’s seconds went in each race, how places changed leg by leg, which side of each beat paid, and which measures moved with finishing place.

    Time budget · Places gained on each leg · Which side paid · What moved with finishing place

  • Tacks and gybes

    How turns are found, which ones are clean, and how the metres lost are measured.

    Tack and gybe loss · Speed and heel through the turn

  • Ranks after the start

    What the start ranks measure and which checkpoint each figure uses.

    Rank after the start

  • Heel and the observed polar

    Which samples go into the heel curves and the speed-by-angle chart, and what they can and cannot tell you.

    VMG by heel · Observed polar

  • Missing and unreliable tracking

    Why some boats or races have holes in the tracking, and how the pages treat them.