Fouling prevention will be unnecessary for the exterior surface of 

 the cold water pipe. The master design^ '° indicates that the OTEC plant 

 should accommodate the increased weight (and decrease in buoyancy) due to 

 fouling. Current plans are to tow the main platform to shore for refur- 

 bishment only after long periods of service. 



With respect to the choice of materials for the cold water pipe, it 

 should be noted that ordinary neoprene sheet fabricated over a steel frame 

 design will not be protected from fouling, although No-Foul laminated over 

 the structural neeprene sheet would prevent fouling for 3 to 5 yr. Sea 

 animals have been known to damage rubber structures, such as surface ship 

 sonar domes . 



Pumps . If refurbishment on a 3-yr schedule is possible, the pumps can use 

 antifouling materials that do not release copper ions downstream into an 

 aluminum heat exchanger. Local flows in excess of 10 knots will prevent 

 attachment of macrofouling organisms. 



The stationary and slow-moving (less than 10 knots) parts of the 

 pumps can utilize organotin coatings. This should be an absolute require- 

 ment of the warm water pumps and is recommended for the cold water pump. 



Housing . One design' includes power modules that are separable from the 

 platform proper. These modules, according to this plan, will be inter- 

 changeable and will be towed into a repair station for refurbishment. In 

 this scenario, conventional paints which are very reliable for 2-yr periods 



can be renewed. Standard maintenance procedures for Navy and commercial 



55 5fi 

 ships can be adopted for these modules. ' The platform stationed in 



the ocean for 10 yr would require a longer-life coating than any presently 



available. 



Commercially Available Antifouling Coatings 



Coatings for Metal, Concrete, Plastic (GRP) , and Other Rigid Surfaces . 

 There are several types of antifouling paints which are recommended for 

 rigid surfaces (Table 8). The cuprous oxide paint, such as Navy Formula 

 121, MIL-P-15931, can be applied over any rigid primed surface. ^6 



37 



