RORC has produced some simplified instructions for owners who wish to measure their own rig or sails for a non-Endorsed certificate. (Although note that we usually recommend obtaining the sail measurements from the sailmaker who made them, to avoid the necessity and inconvenience of measuring them yourself!)
“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!
Louay Habib has interviewed Mike Urwin, joint Chairman of the IRC Technical Committee, with some technical questions about IRC.
Click on this link to see how around 7400 IRC rated boats are distributed worldwide., based on boats holding a valid 2011 certificate.
Following confirmation of general policy, the IRC Technical Committee has issued guidance on measuring x and h at the bow., including explanatory drawings.
You can find this on the Measurement Drawings page.