GRP in seawater will foul. Basil^^ found no damage to GRP panels 

 exposed 14 months in seawater. In quiet seawater, the panels were good 

 collectors of marine organisms. The fouling was removed easily by scraping, 

 and there was no evidence of attack by marine borers or other marine life. 

 Drilling platform operators report no fouling problems in 12-in. -diameter 

 seawater circulating lines operating continuously for approximately 5 yr at 

 maximum velocities of 5 ft/s, but fouling does occur when the lines are 

 shut down. Generally, the magnitude of fouling of GRP piping is less than 

 for some of the metallic piping materials. The reduced fouling has been 

 attributed to the smooth interior pipe walls which provide a poor surface 

 for firm attachment of marine life. Detailed analysis of fouling on GRP 

 is presented later. 



Summary 



GRP materials are inherently corrosion-resistant in the marine environ- 

 ment. Long-time exposure to seawater does not appreciably degrade the 

 physical properties of material. Marine fouling growth occurs but may be 

 removed. Maintenance problems are expected to be minimal. Problems may 

 arise during manufacture since nothing this large has ever been constructed 

 using GRP. Manufacturers are confident that such units are possible with 

 the current state of the art. 



FOULING - OUR REAL PROBLEM 

 Fouling is a general term which encompasses the attachment of soft- 

 bodied or hard-shelled marine organisms and the physical agglomeration of 

 organic and inorganic matter to a surface. However, in our context, foul- 

 ing generally refers to living plants and animals only. Any unprotected 

 marine structure will foul with the maximum accumulation occurring in the 

 photic zone which extends to about 500 to 600 ft deep. From 500 to 600 ft 

 to about 1500 ft, there is a dramatic decrease in fouling. Below 1500-ft 

 depths to the bottom, fouling is so scarce that often it cannot be 



measured. ^2~^^ Although this is true for gross fouling, microfouling 



^^s.^,-,-,, ,, .1 -J 63,66,67 



(slime) IS found all the way to the bottom m decreasing degree. 



Both micro- and macrofouling can be considered insignificant below 2500 ft 



(approximately 4000 ft in tropical waters) . 



26 



