Human had encountered the underwater fouling phenomenon since the times when the first ships and the first primitive waterworks had been built. At first this phenomenon appeared not to have any serious practical meaning, but in the course of time it turned to a real problem.
Any object standing in salt or fresh water is exposed to fouling by algae, barnacles, mollusks, corals and shells. Painting and other activities slow down the corrosion process, but even the toxic anti-fouling paints cannot help against the fouling. The fouling process is accompanied with destruction of expensive paint and varnish coating, which results in the corrosion process increase and biological contamination of the surface manufactured of any material.
All the objects, regardless to their destination, shape and material are equally exposed to fouling. The biological contamination makes a significant adverse effect on economic rates of the river and naval transport operation. Hulls, vanes, keels and backbones, Kingston valves, heat exchangers, thrusters, and even marine propellers of all types of the ships like tankers, bulk-carriers, containerships, bulkers, passenger and war ships, towboats, trawlers, cruisers, pleasure boats and yachts, when getting fouled with algae, barnacles and shells significantly worsen their performance.
The annual biological contamination of the ship decreases its cruising speed 30-50%, and, as a result, resources of the engines and other machinery equipment, at that significantly increasing fueling and maintenance expenses, being the basic operational charge for the water transport.
The stationary waterworks – the offshore gas and oil producing platforms and their bearing constructions, oil-loading and fuelling terminals, pipelines, underwater parts of the power stations, pound nets, nautical barriers and echolocation equipment, and also bridges, buoys, piers, terminals, jetties and other facilities of the fresh and salt water space are much more exposed to the fouling, which results in their proneness to accident, and in some cases in complete impossibility to operate.
Currently, the annual losses of the shipping companies in USA due to the fouling exceed 1 billion of USD, and the total losses all over the world only of the sea fouling exceeds 60 billions of USD, 30% of them being due to the ships fouling.
In practice of underwater hull cleaning, there are 4 underwater fouling stages (FS) distinguished: