The subject of coatings should not be left ■ 'ithout pointing out the need 

 for further stiidy and e:;cperiments on methods of api^lication. Many coat- 

 in'^s can be brushed or sprayed and vfherever the latter method can be 

 safely applied, preat economies are possible. With heavy coatings like 

 the hot and cold coal tar base ones vrhich incidentally are among the 

 very best, however, spray application is still in a rather e:;qDerimental 

 stage and if anj^thing can be done to further the development of such 

 methods of application it virill be most helpful. 



Significant of efforts to maintain our steel water front structures at 

 this time are experiments and trial runs with self-applying coatings and 

 cathodic protection. Both of these methods are only practicable in the 

 particular field of floating dry docks in their possible application to 

 parts of the structures which are in the water all or most of tho time. 

 From this point of view, it is suggested that cat'-'odic protection is 

 somewhat more limited in its possiisilities. 



Self-applying coatings refers to materials which are poured on the sur- 

 faces of enclosed areas such as a ballast tank of a floating dry dock 

 or derrick pontoon. The expected action here is that the material will 

 float on the surface of the contained vjater and attach itself to the 

 exposed surfaces of bulkheads, structural members, etc. by the action 

 of the ^irater going up and down due to pumping or flooding or to the 

 structure's changing its position otherwise, i.e., listing and trimming, 

 S\;rfaces to be treated v;ith these materials do not have to be cleaned 

 down thoroughly but, of course, some cleaning of the v^'orst rust and debris 

 derjosits will facilitate the finally desired action. 'hen attached to 

 the surface in question, the material is supposed to first soften up and 

 remove existing rust and then continue to coat the clean surfaces so 

 that no further rusting will occur. As ^rith every nevf protective method 

 used or experimented with, this method has its good and bad points. In 

 the first place, the material is not cheap. It costs about ,5o,000 to 

 ,,60,000 to start off an 18,0C0 ton dock and, of course, it coste something 

 for additions to keep the coating going, probably about 10^ of the ori- 

 ginal cost per year. It is also possible, as unhappy experience shov/s, 

 to pump the solution overboard with the ballast water if care is hot used 

 in pumping operations. The solution is also blo'em out of the vent stacks 

 in filling operations on some type docks and attempts have been made to 

 develop baffles to stop this action. Finally, the material does not pro- 

 tect the lower 18" or so of the tanks. The overhead surfaces are also 

 a problem but some effect is obtained here by occasionally listing the 

 structure being protected. Experience on this type of material has been 

 gained by using it experimentally in a rather large way of necessity and 

 some encouraging results are beginning to appear. It is still considered 

 an experimental coating, howeverj it is hoped that it v;ill be successful, 

 but bitter past experience forces a skeptical outlook. The composition 

 of this coating is not available because it is a proprietary compound. 

 Some of the ingredients are know, however, like pine oil and lanolin 

 because the manufacturers ask for help in obtaining them inasmuch as 

 they are on the critical list. There is hope of soon developing at least 



D - 6 



