Bonzer Theory

It is amazing to think that in 1970 a couple of teenage kids came up with such an advanced surfboard design as the Bonzer.The Campbell brothers have refined the design over the years but the essence of the Bonzer is a fin and bottom system that works to capture and put to use the energy created by water passing through the tail area of the board. The double concaves in the tail are substantial and the fins act as an extension of the concaves. The side fins, whether a 3 fin or 5 fin model, come in and out of the water with very little resistance due to their angle and shallow depth. This allows for easier rail-to-rail transition and while turning the side fins on the inside rail are almost vertical and allow for more precise edge control.

“The Bonzer” Jim Neece, Surfer Magazine vol.14 no.3, September 1973

When executing a turn water travels diagonally across the bottom of the board. With traditional bottom designs the water that flows off the outside rail escapes as unused energy. The outside fins on the Bonzer deflect the water down and out through the tail. The combination of the long based side fins and the Bonzer concaves redirect more water through the tail than other designs. The Bonzer accelerates out of turns as the water jets through the tail. The larger center fin helps the board hold in the wave and drive through the turn.

Bonzer-5-fin-layout