Structural Engineering Design

Surfboard as a beam

A surfboard is subject to bending, shear and torsion forces when in use and in transport (strapped to the top of a moving car the board wants to bend up from the air pressure).

The proposed hollow timber surfboard internal structure has a plywood stringer running the length of the board and a series of plywood ribs running crosswise. The top and bottom plywood decks are glued to the internal frame so that it acts as one composite section making it strong and stiff.

Foamboard prototype

Having seen a few hollow timber surfboards on the internet I was surprised by how much of the internal structure had been cut away and wanted to apply structural engineering principles to see what kind of design worked.

The structure is designed to be similar to a 'H' section in bending. The stringer acts as the beam web and the top and bottom plywood skins act as the flanges. The plywood cross plies increase the allowable effective width of the top and bottom flanges producing a strong board.

Surfboard as a beam