Anifouling paint schemes to minimize the risk of transmigration of invasive species

Abstract

Biocorrosion or biofouling on ships hull occurs to the attachment of barnacles, mollusks and Other aquatic organisms on the surface of ships which leads to increase in fuel consumption, reduction of the vessels speed, premature failure of the hull, etc. Recent developments in antifouling paints, in general, prevent fouling in about 95% percent of the vessels underwater surface, which ship operators find satisfactory as far as the routine vessel operation is concerned. However, this is not sufficient enough to prevent the transport or invasion of alien species which result in numerous environmental issues that include reduction and extinction of native species and thereby seriously disrupting the natural ecosystems. Virtually all ocean going vessels are coated with antifouling paints, predominant among them are “Self polishing coatings” and “Foul Release Coatings”. Both these coatings depend on hull shear forces caused by the motion of the vessel, by different mechanisms, to result in the hull to be essentially foul-free. Currently hulls are coated with a uniform layer of antifouling paints. However, CFD analysis conducted on various types of vessels have shown highly non-uniform wall stress distribution along the vessels hull. This results in premature paint failure for “Self polishing Coatings” and insufficient shear forces for “Foul release coatings” to release the attached fouling organisms. Both these factors contribute significantly to the transmigration of invasive species. Preliminary results of the current work indicate that certain areas of the vessel such as such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled thereby warranting special attention in such areas. Solutions to these issues include alternative paint schemes/formulations in the identified niche areas to account for non-uniform shear and polishing of paints. Such schemes would ultimately reduce the risk of transmigration of invasive species