THE PROBLEM 



Investigate methods for protecting materials used in naval equipments from 

 damaging effects of underwater environment. 



RESULTS 



1. Test specimens of several construction materials, with and without protective 

 coatings, were submerged in both shallow (10 fathoms) and open-ocean (35 fathoms) 

 environments. Some open-ocean specimens were recovered after 21 months; the 

 remainder were left for continued exposure and evaluation over a longer period. 

 Those from the shallow water were recovered after 18 months. Effects of the 

 submergence and the effectiveness of the various coatings were compared. 



2. Fouling in the shallower environment was much more severe than in the 

 open ocean. 



3. Corrosion-resistant steel was found to be more subject to corrosion and 

 fouling than is generally believed. 



4. The specimens protected with cuprous materials exhibited the least fouling. 



5. Shallow water (depths to 15 fathoms) yields satisfactory results in testing 

 materials for underwater construction, with the least expenditure of time, effort, 

 and money. 



RECOMMENDATIONS 



1. Continue to investigate the corrosive and fouling effects of the marine environ- 

 ment on material used in underwater constructions, and the protective coatings 

 which will inhibit such effects. 



2. Make further studies of the tri-butyl-tin oxide compounds for protective coatings. 



ADMINISTRATIVE INFORMATION 



Work was performed by members of the Materials Sciences Group. 

 The report covers work from December 1965 to September 1967 and was approved 

 for publication 14 November 1968. 



The authors wish to express their appreciation to Dr. Eric Barham and 

 W. Farmer, who identified the fouling organisms; and to W.J. Bunton and 

 J.R. Houchen, who performed the necessary diving to submerge and retrieve the 

 test assemblies. 



REVERSE SIDE BLANK 



