We get a lot of emails from listeners of the Surf Simply Podcast, asking for our thoughts on certain surfboard construction methods; particularly epoxy vs polyurethane; plus we hear in the surf media about exciting new materials being used in surfboard design, like carbon fibre and kevlar. What can we take from this mix of science, pseudo science, fact and opinion? In this two part series, starting with the stringer, we’re going to navigate the material science of surfboard construction.
Firstly, lets go through some of the facts and fiction.
Ok, Epoxy vs Polyurethane, who would win? Now the problem with asking this question is simple; epoxy is a material used to make the skin of a surfboard, where as polyurethane is used to create the core in the middle. So they’re not mutually exclusive. You can commonly buy an epoxy skinned board with a polyurethane core.
So it’s more helpful to break the surfboard down into its component parts, then look at the different methods to manufacture them.
A surfboards core is typically made from some sort of foam, which is then covered by a skin, traditionally fibreglass. Running through the centre of the foam is the stringer; typically a single strip of wood that adds strength and rigidity.
When we look at traditional construction methods, different methods affect weight, strength, and flex pattern. Changes to the core and skin will affect all three, however a change in stringer will only affect the strength and flex, as the weight is almost negligible.
The core accounts for the majority of the weight in a traditional board, approximately 2/3 – 3/4 of the finished total. However the skin and the stringer are what provide most of the strength. There are many interesting ideas out there about how to build surfboards, here we will discuss the common ones.