Retractable hull appendages or those set outside of the symmetry plane are measured separately from the hull measurements to generate an OFF file.




Centerboard measurements include height of the exposed part of the centerboard when lowered (ECM), weight of the centerboard (WCBA) and vertical distance between centerboard centre of gravity positions when fully raised and when fully lowered (CBDA).

Three chords are measured at three heights with the centerboard lowered: at the top of centerboard and at heights of 0.50 and 0.85 of ECM.  The centerboard can be retractable form the hull or from a fixed keel.


Twin rudders


Twin rudder measurements include longitudinal distance from the stem (RCG), the rudder span (RSP), the transverse distance from centerline (RY) and the angle of the rudder axis measured to the vertical (RAN). Chord and thickness are measured at the root and at the tip profiles which completes the rudder geometry.

Twin rudder measurements can also be applied for a single transom-hung rudder on centerline with RY and RAN measurements set to 0.




Bilgeboard measurements are similar to those of twin rudders. BX and BY measurements define longitudinal and transverse position of the bilgeboard leading edge, while span (BS) and chord and thickness (BC and BT) are giving the main bilgeboard dimensions. Angle of the bilgeboard axis to the vertical is recorded as BA, while BF is the percentage of the bilgeboard remaining outside of the hull when the bilgeboard is fully raised.
Bilgeboard measurements can also be applied for a single bilgeboard on centerline with BY and BY measurements set to 0.


Dynamic Stability System (DSS)


The Dynamic Stability System is a horizontal foil that can be extended from the hull with the purpose of increasing stability.

DSS measurements include: a span of the extended wing measured along any curvature (DSS), a maximum chord and thickness (DSC and DST) as well as the angle of the wing to the horizontal axis DSA and distance from the root chord to the centerline of the boat.


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