The math

Every number this platform shows you came from somewhere. These pages say where.

What this section is

Nordic Stars measures things: how far you were from the line, how much of your target you were sailing, how many hours the A2 has flown, how far out the masthead vane is mounted. Each of those is a calculation, and a calculation you cannot see is a calculation you have to take on trust.

So here is the working. Each page takes one thing the platform computes and explains it the way you would explain it to a navigator on the dock: the physics first, then the formula, then what the formula does at the edges — and then, where it exists, the evidence that it comes out right.

Who it is for

Anyone who wants to know before they trust. Navigators and coaches checking whether a number means what they think it means; owners deciding whether a suggestion is worth acting on; a crew reviewing a start on Sunday night. The mathematics goes no further than averages and angles, and every formula is written out and then said again in a sentence.

It is not a reference manual. What each screen does and where to find it lives in the documentation; what each part of the platform is for lives on its own section page — Navigation, Race Control, Debrief Player and Data Analytics. These pages answer the narrower, harder question: how.

What these pages commit to

A formula on a page looks authoritative whether or not it is the one the platform runs, and a stated limit is the first thing an edit for length removes. Four commitments, which every page here is written to keep:

We show the working. Where a page states a formula, that is the formula the platform runs, with the same constants. Not a simplified illustration of one.
Where a number has limits, the page says so. On the page, in the same size type as the claim — not in a footnote. A measurement that cannot separate two causes says which two. A trend that is not a verdict is called a trend.
Nothing here describes something we have not built. Every page describes shipped behaviour. When the platform does not do something a reader would reasonably expect — recompute a derived channel, detect that you have stopped racing, model sea state — the page names the gap rather than leaving it to be discovered.
Evidence, not verdicts. The platform measures and offers; you decide. Where a page cites validation numbers, they are what the tests measured, and the page says what was being measured.

Found something here that does not match what the platform does? That is a bug in one of the two, and we want to know which: support@nordicstars.ai.

The pages

Performance analytics

Guided calibration

Measuring a wind instrument’s constant angle error from your own sailing — the physics, the algebra, what that constant contains (the mounting offset and the day’s wind shear), and the cross-checks that keep a suggestion accurate.

The upwash correction table

Correcting a wind-angle error that changes with the breeze: fixed 2-knot bands, half the measured step and never the step, and interpolation that clamps rather than invents.

The calibration lens

Why a correction is applied when data is read rather than written into it, and the commutation that lets it apply to a whole season instantly.

How a race derives itself

Turning a day of guns, warnings, recalls and one finish press into races, days and regattas — with every window named.

Rollups and series

How a season of one-hertz telemetry stays instant: incremental summaries at ingest, circular statistics for angles, and what happens to a summary when data is deleted.

Targets and interpolation

Reading the tuning sheet at the wind you actually had: interpolation that clamps rather than extrapolates, settings that step, and how a number is graded.

The sail log

How minutes per sail compute themselves from snapshots, why a missed tap costs one boundary rather than a day, and what the performance trend does and does not claim.

Performance trends

How a sailing day becomes a report: steady segments, the three delta-to-target metrics, the smoother and the gate a curve has to pass, the fastest and slowest quartile bands, the season window and the uncertainty band.

Manoeuvre loss

What a tack or a gybe costs and how that is measured: where t = 0 sits, the loss integral over the turn, the distance sailed through it, and the boat’s own best in the same wind as the reference.

Measuring sail degradation

Whether a sail has slowed down, and how sure the platform is: VMG against the polar’s best VMG rather than boat speed alone, steady segments conditioned by mode and wind band, day-clustered bootstrap intervals, two sails compared on the same day, and the sixteen limits the method carries.

The start line

The geometry both the tablet and the debrief run: distance to the line, line bias in degrees, the favoured end, and what makes a boat over early.