Racing in southerly winds gusting to 20-knots, poor visibility on Dublin Bay kept crews on their toes in the ten-boat fleet.
Second overall, and with a first race victory, is Pat Kelly's Storm II from Howth Yacht Club on seven points. Third, on the same points as Kelly is Maybury's clubmate Andrew Craig, the Scottish Series champion sailing Chimaera.
Maybury who sailed to his fourth consecutive ICRA national title back in June on the same race track looks set on adding the J109 national title too, winning two of today's three windward-leeward races.
But expect Storm to put up a fight in the second half of the championship tomorrow as Storms' tactician is Rob O'Leary, who was tactician on Andrew Algeo's "Juggerknot I" last year when they won both East Coast and National Championships.
Maybury has a new tactician this weekend with champion team racer Nicky Smyth replacing Cork Harbour Olympian Killian Collins.
Ryan Glynn, the current J24 National Champion, is tactician on Craig's "Chimaera", where the nucleus of his Scottish Series-winning team are still onboard.