IODA Publishes Class Rule Clarification on Rudder Angle Measurement

The International Optimist Dinghy Association (IODA) has published Class Rule Clarification 2026-001, providing guidance on the correct measurement of the Rudder Leading Edge Angle Alfa, as defined in Optimist Class Rule 3.4.2.1.

The clarification has been issued to ensure a consistent and repeatable measurement method for sailors, measurers and manufacturers when using a digital angle meter.

Class Rule 3.4.2.1 specifies an Alfa angle of 165° ± 1°, meaning that the acceptable range is 164° to 166°. The clarification explains where the measurement should be taken, how the digital angle meter should be positioned and zeroed, and how the resulting Alfa angle should be calculated. 

The document also provides guidance on measurement locations, acceptance criteria and the procedure to follow when a rudder is found outside the permitted range. A rudder measuring outside the permitted range should be considered non-compliant until further assessment, and advice should be sought from the manufacturer regarding any necessary correction. 

IODA encourages National Class Associations, sailors, coaches, measurers and Optimist manufacturers to review the clarification and apply this measurement method when checking compliance with Rule 3.4.2.1.

Download the file with the Class Rulle Clarification

Issued: 3 October 2026