A large square of very stout canvas roped and fitted with ropes at each corner. Known as hogging lines, these ropes enabled crew members to manoeuvre the mat into position under the ship's bottom where the hull was damaged. The canvas was thrummed with rope-yarn or oakum to act as a sealing agent. When drawn over the damaged part of a hull, the pressure of the sea water forced the mat tight against the ship's side and limited the water inflow. The mat was invented in the mid-19th century by Rear Admiral Cochrane of the Royal Navy. See also fothering.
Subjects: Maritime History.