In-water cleaning, also known as in-water surface cleaning, is a collection of methods for removing unwanted material in-situ from the underwater surface of a structure. This often refers to removing marine fouling growth from ship hulls, but also has applications on civil engineering structures, pipeline intakes and similar components which are impossible or inconvenient to remove from the water for maintenance. It does not generally refer to cleaning the inside of underwater or other pipelines, a process known as pigging. Many applications require the intervention of a diver, either to provide the power, or to direct a powered tool.
Applications
Removal of marine fouling for ship performance improvement. Removal of marine organisms to prevent infestation by alien species. Fouling of ships' bottoms by marine organisms is recognised as a major vector for the introduction of invasive alien species, which can have significant economic and environmental impacts. The risk can be mitigated by maintenance of the immersed surfaces to kill or remove fouling organisms before entry into the protected areas. The usual primary method is the use of anti-fouling coatings, which are themselves an environmental hazard due to toxicity. In-water cleaning is an adjunct to anti-fouling in cases where the coating has not been completely effective, and also carries a biosecurity risk due to the potential release of the removed organisms and toxins from the coatings. Removal of fouling and contaminants in preparation for inspection, maintenance or repair work.
Ship bottom cleaning
Methods
Manual methods: Removal of organisms by hand Cleaning using scrapers, hand brushes and scouring pads Mechanical methods: Brushing – the use of a tool with bristles to scrape off the contaminants. Brush cart – a device which transports powered brushes along the surface to be cleaned. Brush carts do not usually include a system for removal or treatment of waste, but it can be done if there is sufficient demand. Brushes that do not directly contact the surface coating can remove fouling without damaging the coating itself. The standoff can be controlled when the cart rolls over the surface on wheels. Some removal of the surface of some anti-fouling coatings may actually improve the performance by exposing a fresh layer with more concentrated active materials.