fin hum

High, piercing sound made by a rapidly vibrating surfboard fin as it moves through water, usually caused by a thin bead of resin along the fin's perimeter, or by a nick or dent near the fin's tip. Fin hum is annoying and can marginally reduce board speed. Repairing a humming fin isn't difficult, and can usually be done with sandpaper, but it can be hard to pinpoint the hum source, especially with ...