IRC ratings are produced as a Time on Time (ToT) number, but you can easily convert an IRC rating (TCC) to Time on Distance (ToD) if preferred:

ToD = 600 / TCC

TCC = 1.100.  ToD = 600 / 1.1 = 545.5 seconds per mile.
TCC = 0.900.  ToD = 600 / 0.900 = 666.7 seconds per mile.

Race organisers running events using the IRC rating system are encouraged to use the IRC logo on paperwork and webpages relating to the event, with the following conditions:

1. The logo shall not be modified, other than re-sizing.

2. RORC or UNCL reserve the right to ask that the logo be removed from any inappropriate paperwork or web pages.

To download:

Click on the small image below, this will show a larger version of the logo (jpg format)
'Right click' on the image and select 'Save picture as...' 
30th Anniversary logo - please use this one in 2014
IRC 30 years logo 2014 no spinlock s

How much time does boat A 'give' boat B?
Approximately:   Divide higher TCC by lower TCC. Multiply by 3600.   Deduct 3600.  Answer is in seconds per hour.
eg.  Boat A rates 1.010, Boat B rates 1.000.
1.010 / 1.000 = 1.010
1.010 x 3600 = 3636
3636 - 3600 = approximately 36 seconds per hour.
The following are ourtesy of Luiz Kahl at Yacht Scoring
Real time calculator:

For Owners: Ever wonder how you are doing against your competition while on the course during the race? Yacht Scoring has created spreadsheet tools to help you easily calculate and answer the usual "How are we doing?" question at any time on the course! Download the appropriate IRC Real Time Calculator linked below and simply enter your class with respective ratings, the race starting date and time and the spreadsheet will do the rest for you. Simple instructions are available in the file. Any suggestions and feedback can be sent to . Let us know how you use it and how it works for you! 

Pursuit race calculator:

For Organizing Authorities: Want to make some races more interesting? Ever thought about a Pursuit Race under IRC? Yes, it can be done! We have developed a spreadsheet to help you organize the starting times for different boats under IRC and provided some instructions on how/where to set the finish line. Download the spreadsheet and give it a try!

We have noted that a significant number of Notices of Race invoke IRC by simply requiring a ‘valid IRC certificate'. With an increasing number of boats now travelling around the world to regattas, this has created problems where a boat from the southern hemisphere (whose certificate remains valid in her own country until May of the following year) attends a northern hemisphere regatta in the first 5 months of a year. A similar issue can arise when a ‘north' boat travels to an event in a ‘south' country.

Organising Authorities are strongly recommended to specifically state the year when invoking IRC, eg: The IRC Rules 2018 Parts 1, 2, and 3 shall apply."

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John Crawley (CAN IRC)  
Jinno (c/o JPN IRC)
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