4.10.1 Alternative Toxins 



Copper is the oldest and best-known biocide for ant i fouling vise. Research 

 is being directed to developing a controlled release structure by 

 incorporating copper powder in a matrix of either epoxy resins or of 

 polyester resins (Miller, 1985) . These would provide essentially a hard 

 finish paint which is not self polishing. Capper phosphate glass is also 

 being investigated for antifouling use. By encapsulating the copper as 

 much as possible the problems with galvanic corrosion are reduced (Rascio 

 et al. , 1978) . Currently this is a major problem with the increasing use 

 of aluminum in the marine environment (Mor et al., 1984). Muminum is 

 used for propellers, outboard motor and inboard/outboard lower units as 

 well as entire hulls (Lennox et al., 1966). The Coast Guard, law 

 enforcement agencies and the offshore oil industry are major users of 

 aluminum hulled boats for their high speed capabilities and ability to 

 take abuse. 



Copper when alloyed with nickel is extremely resistant to corrosion and 

 less galvanically active (Strange, 1986) . The alloy also has antifouling 

 properties. The use of a thin metallic cladding over steel hulls is being 

 investigated by the Newport News Shipbuilding Company. The cladding will 

 serve as a corrosion and antifouling barrier (Chenchrom, 1968; Cziramek, 

 1985) . The Cu-Ni alloy has been added to chloroprene rubber to produce a 

 resilient antifouling surface which has also good sound attenuating 

 properties (Miller, 1985) . At least one vessel has been built in England 

 employing a 90/10 Copper-Nickel alloy to form the hull (Anon. , 1979) . 

 Such a vessel may be able to avoid the use of antifouling paints 

 altogether. However, periodic scrubbing of the hull to remove algae may 

 be required (Griffith, 1985) . 



Other metal-based antifouling formulations include thin films of titanium- 

 palladium alloy, fluorinated organolead compounds, a refinery waste con- 

 taining a melange of Copper, Zinc, Lead, Antimony, Cadmium, Iron, Arsenic 

 and Chlorine (Budon et al., 1985) . In a variation of the same approach, 

 the inclusion of a metals complexing agent, Chitosan, can be combined with 

 cellulose triacetate to produce a membrane which over time accumulates 

 naturally occurring metal ions from seawater to impart an increasing 

 antifouling capability to the film. 



Organic molecules which do not include a metal atom are also being tested 

 for antifouling properties. These include Obtusaquinone, (Goodwin, 1974; 

 Miller et al., 1980 and 1982) Sodlumpentachlorophenate (Anon, 1949) 

 combined with chlorine, and chlorinated rubber coatings. The rubber based 

 compounds offer abrasion resistance as well as good sound attenuation and 

 are galvanically inert. A coating for aluminum hulls which claims both 

 antifouling and anticorrosive properties has been developed from tar, 

 chlorinated rubber, plasticizer and hydrocarbon resin. 



IV-52 



