Nordic Stars
Blog
Notes from building Nordic Stars: how the numbers are computed, and how a crew uses them on the water.
Instruments to the tablet without a laptop
What each of the three telemetry sources needs from you, which one has to be told the tablet’s own address, how a received channel becomes a standard name, and what the status strip says when a feed works and when it does not.
The boat’s clock: why every sample carries GPS time
Which clock stamps a reading and which one only annotates, why the tablet carries the difference between the two rather than a copy of the boat’s timestamp, and what happens on import when a file’s own clock is in doubt.
A sail’s life measured with intervals
How a tap on the tablet becomes an interval a sail was flying, how those intervals accumulate into hours and wind bands, and why a comparison between two sails is reported as an interval rather than as a single number.
Race Control is in the Exocet user manual
What the Exocet user manual now documents in its chapter on third-party software: the prerequisites, the configuration at each end, the variables Race Control sends under the group name NordicStars, and the variables it reads from the Exocet.
The start report: what the gun measures
How the line is built from the pings, what distance and time to the line are at the gun, how a race with no recorded gun still gets a start, and which numbers the report prints as recorded rather than recomputed.
Weather offshore: corridors, bundles and the routed path
Why a forecast is clipped to a corridor around the route, what comes down the button at the dock, how the tablet reads it with the antenna down, and what PATH AHEAD does with two models aboard.
What a tack costs: manoeuvre loss measured against the boat’s own polar
Where a manoeuvre window begins and ends, what the metres it costs are measured against, how the ranking and the season reference in the manoeuvres report are built, and what the printed sheet says it was all measured against.
Pre-start with four values: CURRENT, TARGET, ROUTED and SPEED
What each of the four answers on Race Control’s TIME TO LINE card is computed from, what the burn above them measures, and what AIM, PERF and KILL change in the last minutes before the gun.
How to calibrate the instruments, and how the upwash table is computed
Why a boat is calibrated compass first, boat speed second and wind last, what Guided Calibration measures and what it declines to do, and how a measured step across the tack becomes a wind-angle correction table.
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