CANTCant is the angle a fin makes relative to the bottom of the board. When a board is upside down with the fins pointing up, if the fins point straight up (90 degrees) they have no cant. Canted fins point slightly outward, so the tip of the fin is farther away from the stringer (toward the rail) than the base of the fin. See also, Toe In. Comment from tomatdaum: However, a number of shapers I've worked with will take their cant relative to an imaginary plane perpendicular to the stringer at the center of the side fins. If you make your cant relative to the bottom of the board, boards with vee will have a greater angle of cant relative to horizontal and a board with concave will have less. And, a blank with twist is just a fricken nightmare.