If you want to stiffen your fins, but do not want to go down the Wonderbonding route, you can purchase a set of "Finserts" (Fin and Inserts = Finserts) and move them from one set of fins to anther set.
Finserts were created from a need associated with the fins manufactured by Technisub, the Alas. These fins were a very popular design for UWH players worldwide and still are, for those that stll have a set of them. However, these fins suffered from a design drawback where the footpocket was very flexible and these bending forces applied a load to the bottom of the user's foot when kicking. In addition to this odd and sometimes painful effect, it effectively reduced the amount of force that could be imparted to the fin to propel the swimmer forward.
The Wstik R/D team tried several materials before finally selecting polyproplene for the material to make finserts out of. Original designs employed aluminum, stainless steel and polycarbonate. During initial tests, the metallic finserts were too stiff and hurt the user's foot. Polycarbonate was found to be very durable and provided plenty of stiffness, however, the constant flexing of the finsert during use caused polycarbonate to crack due to the stresses involved. However, when the finsert material was changed to polyproplene, it provided the right amount of stiffness, yet was able to withstand extensive flexure without breaking.
Today, finserts are available in polyproplene as shown below. They come in 4 different sizes, so please specify the length and width of your foot when ordering.
