SLSJ- -f p^ C ° PP f ^ h6at transfer surfaces with pure iron is a distinct 

 possibility. Electroplating of the copper surfaces with pure iron with 

 a maximum protection of the remainder of the steel with a dense epoxy 

 or similar protective treatment would be relatively inexpensive. Some 

 for. of cathodic protection would be desirable. The fact that the RTG 



er aC ion°oF 3 °T inU ° US S ° UrCe ° f X «*«***«* P°™ suggests consid- 

 eration of an active impressed current cathodic protection system. Such 

 systems require continuous, active voltage control to ensure protection 

 and since the RTG will be unavailable for service of such control! ££ 

 appears to be an unsatisfactory solution. 



NOTES ON MARINE FOULING 



It is a useful rule-of -thumb that the effectiveness of anti-foulins 

 surface treatments in seawater is in proportion to their copper content! 

 With pure copper heat transfer surfaces, no fouling would be expected 

 nor was it observed. Neither was it observed on the parted steel parts- 

 it can be assumed that the immersion period was too short 

 rnn .J. the " Pper and steel surfaces, there was a loose gelatinous scum 

 consisting of microscopic organisms; it is referred to in the literature 



iLl, ? ?nt Ty t lm i ™ S f Um W3S ° Ver the entire hul1 «i- was approx- 

 fould IV J nch / hick - There was no strongly adhering ^croscopJc 



foulding, as for instance, barnacles (Figure 23). This is consistent 

 with what was observed in similar but longer tests by Braun (1965), 

 Figure 24. With slightly warmer surfaces there is apparently an enhance- 

 ment of aarine growth which would eventually cause some increase in the 

 filn coefficient of heat transfer and a slight elevation of the surface 



T^L ?erat - reS ' The . BraUn Wrk ClMrlV She ed that * fc « perhaps 5 or 

 6 weeks, a maximum growth would be attained, and no further degradation in 

 heat transfer would be expected. There are no observable inconsistencies 

 in the present work with the earlier, more definitive experimental results 

 as reported by Braun (1965). " 



46 



