Marine Biology (2+1)

Prevention of fouling

Prevention of fouling was done by using copper sheathing in the case of wooden hulls of boats. A great disadvantage of this practice is that copper is subjected to corrosion when exposed to sea water. Later, attention was directed towards a suitable anti-fouling paint. A satisfactory anti-fouling paint has a certain level of toxic substance as its ingredient. There are two types of modern anti-fouling paints.

In the first type, a very heavy load to toxic substance is held in an insoluble matrix and solution of this toxic substance progresses by continuous contact of the toxic particles, penetrating to deeper and deeper levels beneath the surface of the insoluble matrix. In the second type, a much lighter toxic load is bound by a soluble matrix, in which case the whole paint, both the toxic substance and the matrix, slowly dissolve. The most extensively used anti-fouling toxic substance even today is copper. This is incorporated as the red cuprous oxide in the antifouling paint. Mercuric oxide and arsenic compounds as well as organic poisons are also employed for the prevention of fouling. The toxic substance present in the anti-fouling paints, leaches out at a sufficient rate either to repel or even to poison is slowed down making the paint less effective. Further, the poisonous component leaches out completely in course of time leaving the surface non-toxic and safe for the settlement of the larvae of fouling organisms. Chlorination is the best treatment for condenser system in view of the fact that painting inside narrow pipes is difficult and expensive after initial erection. This method is effective against fouling as well as slime film formation in the tubes.

Use of electric currents have also been suggested by the researchers by applying either DC or AC current to the hull at intermittent intervals, which may prevent primary attachment of larval foulers.