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!

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