All boards are legal for all racing except the Olympics.
For the Olympics:
All boards built after October 1 are eligible
Boards built before October 1 and numbered greater than 30000 may be eligible if they are returned to either builder and are re-certified.
From May 1, all boards (with serial numbers greater than 30000) have been built to the same specifications with regard to shape and layup.
To ensure even tighter standards (particularly for the Rio 2016 Olympic Games) additional compliance testing was initiated on October 1.
If any sailor intends to use a board that was built prior to October 1, 2015 at the Rio 2016 Olympic Games then that board will require a builders re-certification to ensure it meets the tighter standards.
