Abstract: A carbon fiber spar is provided which comprises a layer of carbon fiber forming a one-piece circumference and having an integral sail-attaching groove formed by a plastic insert bonded together with the layer of carbon fiber during curing so that the fiber layer forms a hollow for receiving the plastic insert in interlocking engagement.

Abstract: A spar is provided comprising an inner layer of fiber, an outer layer of fiber, a hollow between the inner and outer layers of fiber with the inner fiber layer forming a surface of the hollow such that it is integral in one piece with the spar. The spar preferably includes a cut through the outer fiber layer into the hollow to form a groove for attaching a sail. The invention also provides a method of making spars including the steps of forming a first layer, pressing the layer inwardly along a line to form a groove, applying a second layer over the first, and combining the layers together except along the line. The method preferably also includes the step of cutting through the second layer along the line into the groove.