Ships, antifouling

U.S. MiHtary Specification DOD-P-24647, Paint, Antifouling, Ship Hull, Mat. 22, 1985. 

Despite the attractions of economic forces driving environmental protection, some cautions and failures have been noted. Firstly, the export of hazardous waste to countries where costs for treatment are lower enhances environmental risks during transport and has the potential for transboundary export in the event of pollution. At the same time, the loss of raw material may deprive the home market of an adequate supply of feedstock for the home-based industry. Secondly, there is considerable scepticism that self-regulation of TBT-based antifoulants could be achieved in a timely manner by the shipping industry. This is an instance where the cost benehts to one industry are born by another commercial sector, notably aquaculture. Thus, protection of the marine environment is likely to be aided by economic factors but the role of government, via taxation and standard setting, is not likely to be usurped. Public education and, in turn, pressure, can promote and support corporate environmentalism. 

Cathodic protection of an uncoated ship is practically not possible or is uneconomic due to the protection current requirement and current distribution. In addition, there must be an electrically insulating layer between the steel wall and the antifouling coating in order to stifle the electrochemical reduction of toxic metal compounds. Products of cathodic electrolysis cannot prevent marine growths. On the contrary, in free corrosion, growths on inert copper can occur if cathodic protection is applied [23]. 

Dyckman, E. J. Montemarano, J. A. In Antifouling Organometallic Polymers Environmentally Compatible Materials, Report No. 4186, Naval Ship R D Center, Bethesda, MD, 1974. 

Recently, pollution by organotin compounds was extensive in the environment and its effects on human health are feared. Organotin compounds such as tributyltin and triphenyltin, which are widely used in antifouling paints for ships and fishing nets, are very toxic to aquatic organisms38. These compounds may be accumulated in various organisms through the food chain. 

The case study from chapter 7 is concerned with the design and improvement of chemically-active ship bottom paints known as antifouling paints. A hybrid experiment-model based approach is employed here. Experiments and use of expert knowledge are employed to identify product alternatives, whose evaluation in terms of performance as a marine biofouling protector is verified through a model-based approach. 

When ships are in dry dock, they are supported by wooden blocks. When antifouling is applied, these wooden blocks are sometimes moved in order to apply antifouling to the areas where the wooden blocks were. The blocks are... 

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