IRC Questions & Answers

Where did IRC come from?

The IRC is the most successful, mid-level measurement rule in the world. It was created six years ago by two offshore-racing clubs in Europe—the Royal Ocean Racing Club, in England, and the Union Course Au Large, in France—as an improvement on the Channel Handicap System, a rating rule the two clubs had operated for two decades previous. The rule is now used worldwide.

What kind of rule is IRC?

IRC rates your boat’s speed potential by taking relatively simple measurement data and entering it in a formula to predict speed. Correction factors may be appropriate depending on your boat’s type. The resulting single-number rating is in the form of a “Time Correction Factor.” A race is scored by multiplying each boat’s elapsed time by its TCF and comparing times. This is the same as the time-on-time scoring method used in some PHRF fleets.

What’s involved in the measurement process? 

IRC permits and encourages owner-declared measurement data, and there are relatively few and simple measurements to take. For clubs and organizers running major events using IRC, measurement data taken by an official US SAILING-certified measurer will likely be required. This type of certificate is called “Endorsed.”

Do all boats need to be measured for major events? 

Not necessarily. If your boat has a sistership that’s been measured or has an Americap or IMS certificate, that’s likely to eliminate the need for some measurements.

How does the rule combat design obsolescence? 

Jointly owned and administered by the RORC and UNCL, the IRC’s algorithms are known only in the two rating offices. This confidentiality prevents owners from having boats designed to precisely fit the rule and effectively prevents rapid obsolescence. This feature is central to IRC and will be maintained. While the rule measures each boat and objectively calculates ratings, it also includes limited subjective factors used to bring into line boats that may have a favorable rating..

How often do IRC ratings change? 

The rule is reviewed annually in light of new developments and past results, and ratings are revised accordingly when certificates are renewed. Only if a boat is found to have inaccurate data, would a rating certificate would be revised in mid-season.

What’s the bottom line? 

.Your cost as an owner depends on your boat’s length and type of certificate (Standard or Endorsed). Rating applications are available at and fees are scaled to length. Fill out your application and credit-card info online. Endorsed certificates carry an extra charge, plus measurer’s and boatyard fees if applicable. Certificates take up to three weeks, depending on the season and are valid Jan. 1 to Dec. 31.