The use of tributyltin paints on commercial ships, fishing vessels, and 

 private boats could add another $300 to $400 million in fuel savings 

 annually. Hence, the stakes riding on tributyltin paints amount to almost 

 2 billion gallons of fuel lost forever, or saved for future use, each 

 year. These figures do not include the sums that would be saved from the 

 decreased wear on propulsion machinery and the decreased down time for 

 hull scraping, cleaning, and painting that would result from the use of 

 TBT paints. 



1.1.1 Fouling Organisms 



"Bottom fouling has been the mariner's curse ever since man first set 

 sail" (Russell, 1987) . The growth of marine organisms on boat bottoms has 

 been a war between man and organism; typical examples of fouling organisms 

 are shown in Figure 1.1. 



The growth of barnacles, seaweeds, or tubeworms on a boat's bottom is 

 referred to as "fouling" (Figure 1.2). This fouling produces roughness 

 that increases turbulent flow, acoustic noise and drag. A 10 micron 

 (0.0001 mm) increase in average hull roughness can result in a 0.3 to 1.0 

 percent increase in fuel consumption. For large vessels (bulk carriers) , 

 fuel costs can amount to as much as 50 percent of the total operating 

 costs. For example, the 1985-86 fuel bill of the O.E. II (one of the 

 world's largest ships) was $17 million (US dollars) . 



1-2 



