Surfboard fin retainer

A water riding board comprising:

• a board core of rigid plastic foam having front and rear end portions and upper and lower surfaces, said core having a groove in its rear end portion, said groove extending through the entire thickness of said core between its upper and lower surfaces;
• a retainer and fin box assembly which includes a fin box and a retainer bonded thereto;
• said fin box having upper and lower surfaces and opposite sides and a groove in its lower surface for holding a fin;
• said retainer comprising a part of rigid plastic foam having a lower surface bonded to said fin box upper surface, a lower portion bonded to said opposite sides of said fin box, and a bottom surface lying at least as low as the lower surface of said fin box, said retainer with said fin box bonded thereto being disposed in said groove in said board with the upper and bottom surfaces of said foam part lying substantially even with said board core upper and lower surfaces respectively;
• a surface layer with upper and lower portions lying over said board core upper and lower surfaces, said upper and bottom surfaces of said foam part lying against and bonded respectively to said upper and lower portions of said surface layer.

A method for holding a fin box with upper and lower surfaces, in a foam core of a water riding board, the core having forward and rearward portions and upper and lower surfaces, comprising:

• forming a through groove in said core rearward portion, so the groove extends through the entire thickness of the core between its upper and lower surfaces;
• placing the fin box in a mold having a height at least equal to said thickness of said core at said groove therein, placing a foamable liquid in said mold, closing said mold, and allowing said liquid to foam and expand to fill the mold under pressure and bond to said fin box, to form an assembly which includes a foam retainer bonded to the fin box;
• placing said assembly of said retainer and fin box in said groove, with the fin box lowermost, so the assembly has upper and lower portions;
• applying a surface layer to the upper and lower surfaces of the core including allowing said surface layer to bond to the core and to the upper and lower portions of the assembly.