the deck and bottom halves a polyurethane pre foam strip 61 is placed on the upper inwardly facing surface 36 of bottom 59 before it rises completely the bottom mold and deck mold are joined as shown in fig9 after joining the polyurethane pre foam strip 61 completes rising and forms a bond between the lower surface 18 of stringer 14 and the upper inwardly facing surface 36 this area between the stringer 14 and the surface 32 is referred to as a contact area where the stringer 14 is adhered to the deck piece the outer peripheral flaps 57 and 58 are joined with an epoxy or other appropriate adhesive the assembly of fig9 is cured the mold has separated and the finished product appropriately finished in place of the urethane prefoam other adhesives may be used a cross sectional view showing the bottom of surfboard 10 is shown in fig1 surfboard 10 has a longitudinal axis 62 along which stringer 14 is aligned for a surfboard having a 9 u2032 1 u2033 length a stringer having a length of 4 u2032 has been found to provide an appropriate amount of flexibility in this embodiment prototypes having a space of 3 u2153 u2032 between forward end 15 and nose 43 and a space of 1 u2154 u2032 between rear end 16 and tail 44 utilizing a 4 u2032 stringer has proved a very satisfactory board of course it is to be understood that the length of stringer 14 is variable depending upon the requirement of the end user while.