a. performance specification for this material and the three manufacturers 

 available will then give some real competition and it is hoped 'iith con- 

 sequent reduction in cost. 



As for cathodic protection, in the author's o/m field, it is emphasized 

 here also that this is an experimental field. There have been some strong 

 efforts lately by enthusiasts to try and convince maintenance engineers 

 that cathodic protection is a complete method. This is definitely not 

 true, Cathodic protection has its uses and for some conditions it is 

 definitely pood. For instance, on the 120-mile \fater supply line run- 

 ning from Florida City to Key ;est, Florida, it has been successful in 

 helping to combat leaks, but in a large sense othenirise and elsewhere it 

 has yet to definitely prove itself. The present status of the Biireau's 

 work along this line as regards floating dry docks is briefly as follows: 



The Bureau has under way two test installations on cathodic protection of 

 floating dry docks. One of these is installed on the AFDL-12 at Long 

 Beach, This is an inactive dock and the cathodic protection is on the 

 exterior of the hull only. The system used is the graphite anode- impressed 

 current type and reports to date indicate that satisfactory protection is 

 being obtained. This dock vras nev/ly scraped and painted just before in- 

 stallation of the cathodic protection system. Tiiis installation has been 

 in operation about 15 months. The other installation is on the AFDL-28, 

 an active dock at Key i/est. This also is the praphite anode-impressed 

 current system and installation has been made on the exterior hull 

 and the interior ballast coiupartraents, ■, One report has been received 

 to date and it indicates that the exterior installation is satisfactory 

 and adequate protection is bein^ obtained, but the interior installation 

 is not satisfactory as of this time and the protection beint^ obtained is 

 not adequate. It appears that the inadequacy of the interior protection 

 is due at least in part to a poor arrangement of the anodes. The systems 

 on this dock have been in operation for about 9 months. This dock also 

 had been nevdy painted just prior to installation of the cathodic pro- 

 tection system. No test installations have yet been made^ making use of 

 magnesium anodes, chiefly because satisfactory arrangements have not yet 

 been completed with the magnesium people. 



As for other cooperating groups, the Bureau of Ships is making test instal- 

 lation on some of their ships, both active and inactive, and their exper- 

 ience has been in t^eneral about the same as that of the Bureau. 



The Maritime Commission has had test installations of both the graphite 

 and magnesium systems on their ships for several years and it is under- 

 stood that they feel that the protection being obtained is adequate. 

 However, it is understood that this is based upon the potential readings 

 which are taken from time to time and is not based upon actual observa- 

 tions by docking ships after the installation has been in effect for 

 several months. 



The Canadian Navy has been studying cathodic protection for several years 



D - 7 



