Several Sailmakers have intentionally attempted to circumvent IRC rules 2.4 and 2.5 by developing headsail foot shelf profiles that artificially reduce the headsail measurements, reducing the IRC rating without a corresponding reduction in performance. To do this the curve of the foot is exaggerated to create a far larger foot shelf than required. This means that the measured tack point and clew point are not extended, and therefore move up the luff and leech, artificially reducing the sail’s dimensions.

IRC Rule Notice 2012/02 addresses this issue with the introduction of Headsail Foot Shelf

Previous IRC Notices and Interpretations

“What is headsail LLmax?”

We sometimes encounter some confusion about what LLmax is, and when it needs to be declared. One of the common misconceptions is that LLmax is the length of the longest possible headsail luff that would fit on the forestay; this is NOT the case!  

Please download this PDF for further explanation and a sketch

Have you looked at the IRC website?   Here you can see information on new designs, technical IRC information including advice for race organisers, and much more.

Concentric cIRCles contains periodic articles about IRC racing around the world, why not take a look?

Mike Greville, Commodore of the Royal Ocean Racing Club interview with Louay Habib.

“My primary aim during my tenure as Commodore is to ensure that the Club is left in at least as strong a position as it is today - in terms of its standing in the yacht racing world, its attractiveness to members and its financial stability. Those strengths should be sustainable for the future with the next succession of leadership and management in place.  

Louay Habib has recently interviewed Mike Urwin about various technical aspects of IRC.

Read the full interview on the IRC website

Following GBR's adoption of the In-House Certification for the Endorsement of sail data for IRC, the RORC Rating Office has written some guidelines in the form of Questions & Answers to help owners and sailmakers.

Click here to view the IHC Q & As.

If you have any further questions please contact us at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or call 01590 677030.