The purpose of bulge is to start the ball further to the right on toe shots and further to the left on heel shots to compensate for the unwanted slicing or hooking sidespin created by off-centre shots. When a shot is hit off the toe, the head rotates around its centre of gravity and hook spin is imparted to the ball. A shot hit off the heel rotates the opposite way around its centre of gravity and slicing spin is imparted to the ball. Bulge starts the off-centre shot further to the right or left and encourages the ball to spin back towards the target line.
