The Douglas fir panels differed in their ability to resist biological borers. 

 The shallow-water panel maintained its entire outline, while the deep-water sample 

 was almost destroyed. It may be that the fouling elements at the shallower location, 

 finding lodgement and rapid growth possible on the bare wood, grew so rapidly that 

 they made penetration by the borers more difficult. A corresponding effect was 

 noted on the aluminum plates; the deep-water panel was severely corroded over 

 its entire surface, while that from the shallow water had apparently been protected 

 by the heavy growth of fouling organisms. 



The "corrosion resistant" steel proved to be more subject to corrosion and 

 fouling than is generally believed. The more severe corrosion of the sample from 

 the SQUAW might indicate the effect of pressure at greater depth or, possibly, as 

 in the case of the wood and aluminum panels, the heavier biological fouling in the 

 shallower environment protected the sample there from corrosion. 



The panels showing the least fouling were those protected with coatings 

 containing cuprous oxide. Steel panel #6 was the cleanest of all tested, with 

 #3 second best; panels #11 and #1 were slightly more fouled. Steel panels #9 and 

 #10, coated with tri-butyl-tin oxide compound, were considerably fouled by the 

 shallow ocean water, but only #9 was fouled in the deep water. The absence of 

 fouling on #10 in the SQUAW installation cannot be explained. The tin compounds 

 should be investigated further, as they are relatively new, whereas the copper 

 materials have an extensive history as antifoulants. 



The anticorrosion coatings functioned as expected, except for panel #11 

 from the SQUAW. There are several possible causes for this failure, none of which 

 can be accepted definitely until the remaining samples have been retrieved and 

 inspected. 



The expense and effort involved in deep-water testing are not justified, 

 since the more rapid fouling of materials in shallow water expedites evaluation of 

 corrosion-resistant and antifoulant coatings. 



