Thin boards formerly placed between the ship's body and the sheets of copper, to protect the planks from the pernicious effects of the worm. Tar and hair, or brown paper dipped in tar and oil, is laid between the sheathing and the bottom. In 1613 a junk of 800 or 1000 tons was seen in Japan all sheeted with iron; and yet it was not attempted in Europe till more than a hundred years afterwards. But by 1783 ships of every class were coppered.