Usually wedge-shaped wooden, metal (1) or bone hand tool (approx. 20-25 cm long) with rounded edges and a straight handle, sometimes sculpted in the shape of a piece of rope (2). It is used by the sailmaker to flatten the seams of the sail. The sailmaker sometimes uses the back of his knife for this purpose.
See also the closer's hammer and the furrier's rubber. [MOT]
(1) NOORDRAVEN & DE BOER: 101.
(2) ASHLEY: 20.