At certification, when the difference between the QBL dimensions is found to be outside the class rule limit, what is the correct action?

A 
Question Details

At certification, when the difference between the QBL dimensions is found to be outside the class rule limit, what is the correct action?
Answer

Large differences in the QBL lengths will occur due to one or a combination of the following:

  • lack of symmetry of the hull
  • placement of the hull off the centreline of the measurement equipment
  • lack of alignment of the hull with the centreline of the measurement equipment

As the permitted sail area can be increased (where there will be a QBL penalty) by enhancing the difference in port and starboard QBL measurements, the class rules specify a limit to that difference.

There is no requirement in the class rules for the centreline of the hull to be on the centreline of the measurement equipment. Moving the hull laterally on the measurement equipment can restore equality in the measurements. A rule of thumb that can help here is to move the hull one fourteenth (1/14) of the difference between the QBL measurements towards the side of the shorter measurement.

Alternatively, if the owner is prepared to lose some permitted sail area, the lower QBL dimension can be raised artificially to within the specified difference from the larger QBL dimension before recording.