A surfer balancing on a surfboard
Image credit: Joakim Lloyd Raboff / Shutterstock.com
Surfboards are elongated platforms used by surfers to ride waves. They were originally invented in Hawaii, where they were referred to as "papa he’e nalu", and made of heavy local wood. Since then, surfboard innovation has turned them into the sleek, modern boards we see today.
There are generally three different types of surfboards, each targeting a specific level of rider. Each level of surfboard is composed of different materials. The composition of these materials is directly affected by how the surfboard will be used. A beginning rider, for instance, needs a board that can handle getting beat up, while an advanced board will need to have very specific torsional requirements.
Foam and Fiberglass
Foam surfboards use multiple different types of foam in their construction. It is important to note that all surfboards, whether novice, intermediate, or advanced use some type of foam. The specific type and application of the foam is what differentiates the boards.
The first foam surfboards were constructed from polyurethane foam and encased within a polyester resin. Unfortunately, this set-up provided a "soft ride" which resulted in a large degree of twisting and flexing. As intermediate and advanced boards began to utilize superior technologies, novice boards were forced to follow.
Surfboard Construction Time-Lapse
Video credit: Berta River / YouTube
More modern novice surfboards now use an epoxy resin and prolapse polystyrene (PPS) foam, rather than polyurethane and polyester. Epoxy resins come with various advantages over their predecessors, such as emitting less than half of the volatile organic compounds (VOCs) that polyester resins emit during manufacturing.
All surfboards will typically use fiberglass cloth, and the type of construction is determined by the type of resin and foam used in the core. Epoxy and expanded polystyrene (EPS) boards use resin, and PU boards use foam. Both of these methods also use fiberglass cloth.
Polyurethane foam blanks are used in traditional fiberglass boards. These types of boards are hand-, or machine-, shaped out of a polyurethane foam core. The core is then lined with fiberglass cloth and laminated with polyurethane resin. Finally, the board is cured and sanded to give a smooth surface finish.
Open and Closed Epoxy
The first type of epoxy surfboard is called an EPS board. In these boards, the EPS is a beaded foam. This beaded foam is analogous to that which you might find in a car bumper. Due to its open cell nature, this type of foam maintains its structure, but also readily absorbs water.
There are limitations to EPS, however. The material has low tensile and compressive strength, and is has low formability due to its beaded shape. This is why lower-priced beginner boards are typically expanded polystyrene at their core. While these epoxy boards hold up well when compared to epoxy resin boards, if an EPS board cracks, it must be immediately repaired before returning to service.
Closed cell, or extruded polystyrene core surfboards, are much better at repelling water and are far more resistant to damage and compression. One of the main differences between expanded and extruded styrene cores is the flex pattern. Because extruded cores have a closed cell structure, they respond much better under pressure, which is the reason why most advanced boards are constructed in this fashion.
Advanced surfboards use a highly technical combination of materials
Image credit: Pavel Ilyukhin / Shutterstock.com Hand-Shaped and Molded
Hand-shaped epoxy surfboards are quite similar to fiberglass surfboards, with the main difference being that the polyester resin has been replaced with epoxy resin and an EPS core replaces the polyurethane core. In this configuration the EPS is hand-shaped and then laminated with epoxy resin and fiberglass cloth. Hand-shaped boards are quite common amongst well-known manufacturers due to the high availability of EPS foam cores.
Molded epoxy surfboards are created based on the dimensions of a traditional, hollow fiberglass mold. The mold is then injected with EPS foam and covered with multiple layers of fiberglass cloth and epoxy resin. In some cases, a layer of high density foam is added to reinforce the structure. The board is then placed into a vacuum chamber to ensure all of the materials are properly compressed.
A heating element is sometimes built into the mold so that the epoxy resin can cure at a higher temperature. This final step greatly increases the torsional strength of the board. In rare cases a strong, lightweight, composite PVC layer is compressed into the EPS and then glassed over with an epoxy resin. This step adds a tremendous amount of extra strength, is highly technical, and represents the pinnacle of surfboard types, used mainly by the most advanced surfers.