Patent ID: 7451547

Claim:
A device for marking a line on horizontal surface surrounding and following a curved perimeter edge of a swimming pool, the device comprising: two guide wheels having a common horizontal plane and having respective vertical axes of rotation; a horizontal centerline passing between the guide wheels; two support wheels having respective horizontal rotation axes located on opposite sides of the guide wheel horizontal centerline; two secondary wheels having respective secondary horizontal rotation axes located on opposite sides of the guide wheel horizontal centerline; a rigid frame having a first end and a second end; the support wheels secured to the first end; the second end having a downwardly extending neck portion; the guide wheels secured to the neck portion; the secondary wheels secured to the frame between the guide wheels and the support wheels such that the secondary wheels and the support wheels have a common contact plane; a rigid handle extending generally upward from the frame to a grip configured to be grasped by a user standing on the contact plane; a marker extending downward from the frame, and having a horizontal marker distance dimension from the guide wheels; an adjustment means for altering the marker dimension over the range of three to twelve inches; a biasing means for biasing the marker against a horizontal surface on the contact plane; such that the support wheels and secondary wheels may be placed on a horizontal working surface while maintaining the guide wheels in contact with a vertical wall below the support wheels and between the support wheels and the guide wheels, while the marker is biased against the working surface.