After 5 months exposure, concrete containing a methoxychlor/TPTH/Cu,0 
mixture exhibits excellent antifouling properties. The exposure of 
these specimens will continue, and the efficacy of this concrete should 
be determined after a longer exposure. 
The two proprietary coatings exhibit excellent antifouling properties, 
but these also have been under test for only 5 months. Because the 
organotin polysiloxane coating is the least expensive of any of the 
antifouling systems investigated, exposure should continue. 
Alternatives to the use of any antifouling chemicals in the concrete 
exist. The hull could be scraped periodically by divers. Cold water 
pipes could be constructed of relatively inexpensive polymeric materials. 
They could be replaced as necessary, and the fouled pipes brought to a 
convenient place for scraping. These alternatives should be investigated 
to determine the most manpower- and cost-effective methods of controlling 
fouling of an OTEC facility. 
ACKNOWLEDGMENTS 
Until his death in 1978, Dr. Harold Vind, who originally worked on 
this project at CEL, inspired and continued to aid the author; his help 
is gratefully acknowledged. 
Dr. Shirley Pomponi-Taylor, now of the University of Maryland, 
exposed test specimens and accumulated weight data at the Key Biscayne 
exposure site. Mr. John Keeton and Mr. John Crahan of CEL were respon- 
sible for the mix design and preparation of the concrete test specimens. 
REFERENCES 
1. Lunn, Iver. Antifouling. London, England, BCA Publications, 1974. 
2. Woods Hole Oceanographic Institution. Marine fouling and its pre- 
vention. Menasha, Wis., Geo. Banta Co., 1952. 
3. Naval Civil Engineering Laboratory. Technical Note N-1211: Anti- 
fouling concrete--Preliminary report, by J. S. Muraoka. Port Hueneme, 
Caillite Jans O72: 
4. Civil Engineering Laboratory. Technical Note N-1392: Antifouling 
marine concrete, by J. S. Muraoka and H. P. Vind. Port Hueneme, Calif., 
May 1975. 
5. U. S. Patent 3,784,357: Protective surfaces or liners for sub-aqueous 
structures, by J. S. Muraoka, Jan 8, 1974. 
6. American Society for Testing and Materials. ASTM C143-78: "Standard 
test method for slump of portland cement concrete," 1979 Annual Book of 
ASTM Standards, Part 14. Philadelphia, Pa., 1979, pp 97 and 98. 
7. Civil Engineering Laboratory. Technical Memorandum M-52-77-8: 
Preliminary investigation of methods to increase the strength of anti- 
fouling marine concrete, by H. P. Vind and J. R. Keeton. Port Hueneme, 
Calif., May 1977. 
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