New AMCAP II Rating System Explained

For the first time the Americap II handicap system will be used to determine Chicago Mackinac winners. This holds true for all divisions except the multi hull division which will use PHRF.

Americap II is a rating system combining multiple elements. Included are boat measurement(similar to IOR), Wind velocity and direction (familiar from IMS) and a combined time on time/time on distance scoring (both methods used in PHRF). Unlike PHRF there is are no subjective components that maybe finessed by boat owners.

For those racing, or spectating results are figured a little different with Americap II. A 2 part equation is used, infolding multiplication and subtraction.

The equation is as follows: CT= (A * ET) - (B * Distance)

Corrected time= Corrected Time
ET= Elapsed Time in seconds
Distance= Distance
A= Time on Time Co-efficient (seconds per mile)
B= Time on Distance Co-efficient (seconds/second)

The scratch boat has an A coefficient of 1 and a B coefficient of 0.

For instance the potential record breaker Alchemy has an A of 1.0657 and a B of -11.6.

 Rosebud which is a Transpac 52 has an A of .9335 and a B of 40.9. 

Bantu which is an older and slower boat has an A of .6698 and a B of 67.6. In other words a faster boat will have a higher A number and a lower B number.

To properly compare boats both coefficients and parts of the equation must be used.

The ratings displayed on the Chicago to Mackina official scratch sheets at http://www.chicagoyachtclub.org/racetomackinac/ScratchSheets/index.htm are the 10 knot rating.

It will be interesting to see how this new more sophisticated rating works compared to the one number fits all PHRF previously used.