Westward yacht with Hall Sensors - Part 1

Detect if the Westward yacht is sailing on Port or Starboard tack or heading too much into the wind.
Hall Sensors detect the strength of a magnet. I have aligned two and can estimate the location of a magnet as it passes over them (in a straight line) with a clearance of, say, 3 cm. The sensors are under a plastic cover. Hall sensors are an upgrade from using reed switches which only tell if the magnet is close.
More information at www.roboticboat.uk/Microcontr...
Proboat Westward 18
Chad Valley 4ft Ocean Fill 'N' Fun Kids Paddling Pool - 219L. Size L122, W122, D25cm.