I have seen racers use aerosol spray paint to paint numbers on sails using a stencil, but I don't know if the paints were water based or not. I am guessing not.
No apparent damage after a year or two of service.
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.