Copper, the most noble of the metals in common use, has excellent resistance to corrosion in the atmosphere and in fresh water. In seawater, copper nickel alloy has superior corrosion resistance, coupled with excellent anti-fouling properties.
Copper cladding of wooden-hulled warships, introduced by the Royal Navy in the 18th century to prevent damage by wood-boring insects and worms such as the teredo, was discovered to prevent biofouling by weed and molluscs. This meant that ships could stay at sea for long periods without cleaning. Nelson's successful blockade tactics, and subsequent victory at Trafalgar, was partly due to the superior speed of his clean-hulled ships.
The addition of nickel to copper improves its strength and durability, and also the resistance to corrosion and erosion in natural waters, including seawater, brackish and treated water. These copper alloys also show excellent mechanical properties - resistance to stress-corrosion cracking and corrosion fatigue. The added advantage of high resistance to macro-fouling means copper alloy is an ideal material for use in marine and saltwater environments for commercial and naval shipping, desalination plants, heat exchangers and equipment, sea water and hydraulic pipelines, oil rigs and platforms, fish farming cages, seawater intake screens, offshore renewables, ship and boat hulls and more.