Anti-fouling paint 1

Anti-fouling paint or bottom paint is a specialized coating applied to the hull of a ship or boat in order to slow the growth of organisms that attach to the hull and can affect a vessel's performance and durability.
Hull coatings may have other functions in addition to their anti-fouling properties, such as acting as a barrier against corrosion on metal hulls, or improving the flow of water past the hull of a fishing vessel[1] or high-performance racing yacht...
In the Age of Sail, sailing vessels suffered severely from the growth of barnacles and weed on the hull, called "fouling." Thin sheets of copper or Muntz metal were nailed onto the hull in an attempt to prevent marine growth. One famous example of the traditional use of metal sheathing is the clipper Cutty Sark, which is preserved as a museum ship in dry-dock at Greenwich in England. Marine growth affected performance (and profitability) in many ways.
The maximum speed of a ship decreases as its hull becomes fouled with marine growth.
Fouling hampers a ship's ability to sail upwind.
Some marine growth, such as shipworms, would bore into the hull causing severe damage over time.
The ship may transport harmful marine organisms to other areas.[2]

The inventor of the anti-fouling paint was Captain Ferdinand Gravert, born in 1847 in Glückstadt (Schleswig-Holstein, now in Germany but then Danish), who sold his chemical formula in 1913 at Taltal, Chile.
Captain Alex Gravert has valuable documentation about this.

Modern anti-fouling paints
In modern times, anti-fouling paints are formulated with toxic copper, organotin compounds, or other biocides—special chemicals which impede growth of barnacles, algae, and marine organisms.

"Hard" bottom paints, or "non-sloughing" bottom paints, come in several types. "Contact leaching" paints "create a porous film on the surface. Biocides are held in the pores, and released slowly."[3] Hard bottom paints also include Teflon and silicone coatings, which are too slippery for growth to stick. SealCoat systems, which must be professionally applied, dry with small fibers sticking out from the coating surface. These small fibers move in the water, preventing bottom growth from adhering.[3]

following this link
http://en.wikipedia.org/wiki/Anti-fouling_paint

the manner in which a boat's hull is affected by fouling 

Cleaning the hull by fouling takes money, time, labour and euipment, maily used water pressured, the process precedes the following steps for applying the bottom paint or the antifouling coating., and thsi should be done only after the ship is being docked in the shipyard. Despite the standards procedures each cleaning project is unique and should be treated likewise organizing the operations, organizind human resouces, sincronising thei efforts with suppliers and time availble for each stage.

Hull coating in shipyard on a docked vessel