What is IRC?

IRC is a rating system based on a time-on-time calculation (TCC) of a boat’s elapsed time. It is a simplified rule and works on the basic principle that the faster the boat, the higher the TCC. IRC is considered a “secret” rule, the intention of which is to prevent the development of design-optimised boats that can take advantage of their rating.

Further information and full explanation of the rule can be found in the the IRC Yearbook or from the IRC website:
One of the principle elements of the IRC rule is that it evolves from year to year, so please ensure that you always refer to the current version of the IRC Yearbook to bring you up to date with the latest changes.

Why use IRC?

IRC rates measured data such as a boat’s weight, length, draft, rig and sail area, as well as special features like water ballast, canting keels and bowsprits, to allow a wide range of keelboats to compete against each other on a similar playing field.

IRC has been adopted on a wide international scale and is the main handicap category used for several world-renowned regattas such as:

Cowes Week, Fastnet Race, Rolex Sydney Hobart Yacht Race, Hamilton Island Race Week, Key West Race Week, Phuket King’s Cup and China Sea Race.

Principles of IRC

IRC is generally considered a self-measurement rule; however, the practice of using Endorsed certificates is considered the norm in Australia. Endorsed certificates require that all rated information on the certificate has been audited by an accredited official and confirmed by measurement. Boats with an endorsed certificate must also be weighed on certified scales or obtain a weight from another verified source, such as a standard design weight or One-Design class weight. Sistership weight and designer's (factory) weight will not suffice for an endorsed IRC certificate.

Any changes made to a boat after its initial rating has been supplied must be declared by the owner so that the rating is still current and applicable.

IRC also applies an age allowance factor to a boat’s rating. This is automatically applied after 3 years and uses the average of the series and age date in its calculation. It should be noted, however, that a rating won't necessarily decrease each year as a result of age allowance.

Boats are individually rated so boats of the same or similar design will not necessarily have the same rating. Some standard measurements can be used for production boats of a standard design but all rig and sail measurements will always have to be provided. Class measurements and ratings are also available for valid One-Design classes. For a list of valid One-Design classes and standard production designs, please refer to the full listing on the IRC website: