- Surfboards split into two categories--longboards and shortboards. Both board types offer removable or permanent fins underneath. It is the fin's purpose to stabilize the surfboard and keep it from sliding to either side. Fins are removable on newer boards, allowing users to adjust the size for changes in board performance and stability--fins allow for stabilizing control of the board. Both longboards and shortboards have special bottoms that can curve to varying degrees, changing how much of the board is in the water.
- In addition to the fin, a surfboard consists of several other parts. There is the bottom, the deck, the concave, the bulb, the leash and the leash cup. The bottom is the side of the board which resides in the water. The concave is the collection of grooves and contours underneath the board. The concave directs water with the fins of the board and influences the speed and guidance of the board. The top of the board is called the deck. This is the area where surfers apply wax. The cord, which attaches the surfboard to a surfer, is called a leash. It attaches to a small bar on the board known as the leash cup. The front of the board is the nose and can be either round or pointed. The edges on the sides of the board are called the rails. The tail affects how the board responds to the surfer's movement. The rocker and stringer are the curve on the board's bottom and the thin wood running from tail to nose, respectively. The rocker assists the board's behavior when working with tight curving waves, and the stringer increases the board's strength.
- Surfboards use Newton's laws of motion to operate. They work with the scientific fact that the movement of matter contributes to maneuvering and staying afloat. Newton's first law relates to surfing in that an object in motion, like a water wave, will stay in motion. An object at rest like a floating surfboard, will continue resting. To gain motion, a surfer must paddle to catch waves. Now Newton's third law comes into effect. Every action has an equal and opposite reaction. When a surfer forces down one edge of the board, that same edge pushes into the water. The water then pushes back up against the board. Because of this effect, the board starts to turn and move.
- The surfer pushes down on the board, the board pushes the water and the water pushes back. The board provides stability and buoyancy for the surfer as he rides the waves underneath.
