According to the Class Rules Section 2.4, all boats must have a valid measurement certificate.
Here is the link to find the AIODA form and information you need to register your new Opti and get a sail number or change ownership details in your measurement book.
and don’t forget How to position sail numbers
Sail Number Style/Colour – Racing Rules of Sailing Appendix G
(a) National letters and sail numbers shall be in capital letters and Arabic numerals, clearly legible and of the same colour. Commercially available typefaces giving the same or better legibility than Helvetica are acceptable.
YA Equipment Regulation 4 – Boat Identification
In accordance with Yachting Australia Equipment Regulation 4 all boats are required to have clearly marked externally on their transom or on both outboard sides of the hull the following information:
a) The name of the boat in letters/figures at least 50mm high and 8mm thickness;
b) The registered sail number;
c) Name of the owner’s YA affiliated Club. Note: while the name of the Club may be abbreviated it is recommended the name be in full where possible as another club may also use the same abbreviation.
IODA Class Rules Addendum – ISAF Advertising Code
IODA replacement forms for measuring Optimist equipment
Sail Measurement form – nusailform082013
Official IODA sail labels available – $12 each plus $2 postage. Contact the AIODA Registrar
Sail buttons/labels are required on all measured Optimist sails.