All fins are loaded on a test bench where bend and twist is measured to ensure the fin has the proper deformation values. Afterwards the fins are blind tested by (semi-)professional windsurfers to couple a feeling to the actual deformation of the fin. A “blind test” is a method of testing in which the participants have no idea about what they’re getting. Applying this method is very important to avoid errors arising from bias. Without this feedback there is no starting point for a new layup calculation / design.