Method of making surf fin including injection molded pre-impregnated composite fiber matrix inserts

A method of forming a fin configured for use with a water sports board, the method comprising the steps of:

• providing:
• a mold having a mold cavity at least partially defined by a pair of opposed mold cavity faces;
• a first insert pre-preg sheet including a plurality of first structural strands bonded by a first resin material;
• and
• a second insert pre-preg sheet including a plurality of second structural strands bonded by a second resin material;
• placing the first insert pre-preg sheet and the second insert pre-preg sheet within the mold cavity;
• injecting a third resin material under pressure into the mold cavity between the first insert pre-preg sheet and the second insert pre-preg sheet to:
• urge the first insert pre-preg sheet and the second insert pre-preg sheet away from each other and towards respective ones of the pair of mold cavity faces;
• and
• dispose the third resin material between the first insert pre-preg sheet and the second insert pre-preg sheet to space at least a portion of the first insert pre-preg sheet from the second insert pre-preg sheet;
• and
• injecting a core substance only in the form of a gaseous material into the third resin material to form a unitary hollow volume completely enclosed within the third resin material.