Note:  Do not rely on this information. It is very old.


Copper-bottomed, or Coppered. A vessel is said to be coppered when her bottom is sheathed with thin sheets of copper to protect it, if of wood, from the ravages of worms and the accumulation of vegetation, and, if of iron or steel, from corrosion. In iron or steel vessels, in order to preclude galvanic action, wood is interposed between the fabric and the copper; and even in wooden vessels, for the same reason, all the bolts and fastenings of the hull beneath the water-line should be of copper and not of iron. Vessels thus built are said to be "copper-fastened." The first ship in the navy to be copper-bottomed was the frigate Alarm in 1758. By 1783 the practice had become general. Modern iron and steel vessels, if they can be frequently docked for cleaning, are not coppered. Their bottoms are merely protected with one of the numerous preservative paints, or anti-fouling compositions, But ships that cannot, for any reason, be often docked, are still coppered, or sheathed with zinc, over wood.