At the 2019 World Sailing meetings their Racing Rules Committee approved changes to the rules relating to sail numbers. The changes introduce a requirement that numbers be of a contrasting colour to the body of the sail.
The changes approved apply to rules G1.2, 1.3 and 1.4 and can be seen in submission 216-19 at https://www.sailing.org/tools/documents/21619RacingRulesofSailingRulesG1.2G1.3andG5-.pdf.
The main thing that officials and boat owners need to know is that sail numbers will have to be of a contrasting colour. Boat owners who have sail numbers in a dark colour on a dark sail will need to have their sail numbers changed to something more contrasting by 1 January 2021. This problem is typically seen on ‘carbon’ coloured or dark grey sails.
Sail makers building new sails or doing repairs should also check the sail numbers and offer advice on whether the numbers need to be replaced with some of a contrasting colour.
Race officials serving on race, technical and protest committees may have to exercise some judgement when educating boat owners and crews on the upcoming rule change, and how to address it after 1 January 2021. Attention is drawn to G4 which guides a protest committee to warn and provide time to comply before penalising a boat.
– Australian Sailing