their character, which are exposed to severe water front conditions. 

 For instance, a radio tovrer exposed to salt spray and wind-blovm sand 

 might give just as much if not more trouble than, let iis say, a moor- - 

 ing buoy with its ground tackle which is actually in the water all the 

 time except when it is lifted and taken ashore for overhaul. BuDocks 

 has had actual examples of just such cases. There are paint coatings 

 which are readily applied to moorings and which will hold them in 

 reasonably good condition for quite some time but these same coatings 

 are not practicable for application to radio towers and probably would 

 not hold up even if they could be applied. Incidentally, it has been 

 found that the only thing to do with towers so exposed is to paint them 

 more frequently with our standard structviral steel paint coatings with 

 a higher content of zinc oxide to harden the siorface of the paint. 

 Typical locations where this has been necessary are Portsmouth, N, H,, 

 and Key j'est, Florida. This same tower problem occurs in buildings, 

 vehicles, cranes, railroad stock, etc. 



Getting r ight down to structures directly exposed to wind and waves, 

 however, and with particulai' reference to s alt water exposure, there 

 are many problems running from the attacks of marine organisms on treated 

 and untreated timber structures, both fixed and floating, with which this 

 body is probably most concerned, to those having to do vfith corrosion of 

 steel and deterioration of concrete and again, strange to say, in both 

 fixed and floating structures. 



Taking up the first of these subjects, long personal experience in Navy 

 construction work has amply testified to the terrible damage done by 

 marine borers. These pests are to be combatted all the time, but it 

 is when they invade new areas as they are apt to do at any time, that 

 they probably give us the most trouble. There are cases like the sud- 

 den attack on the timber structures at the Mare Island Naval Shipyard 

 in the 1920 's xirhen prolonged up-country dry spells changed the salinity 

 of the upstream waters thus permitting the borers to invade and live 

 in waters not formerly suitaisle for their existance. Such an attack 

 could and does literally put a Navy Yard water front out of commission 

 and if it should come during a period of emergency a very serious situa- 

 tion would result, Sometirres too, like at New York, where the harbor 

 vraters are so polluted by sewage and industrial wastes as to eliminate 

 the action of borers when and if anti-pollution measures are. put into 

 effect and are effective, it is necessary to watch out for timber water- 

 front troubles of all kinds. These examples point to the need for 

 continuous study of new construction and applications to existing 

 structures to render them immune to borer action v/hich will be virell 

 covered later. At the same time, studies on marine borers must con- 

 tinue to seek the best means of limiting their depredations where it 

 is not practicable or economical to build such applications into the 

 structure originally, A typical problem of this type is the protection 

 of the intei'iors of timber floating dry docks. The permanently exposed 

 exterior salt v^ater surfaces can be and are protected in the conven- 

 tional manner, i.e., by the application of tar, Irish felt and creosoted 

 sheathing, Itiese measures are not very practicable internally, of course. 



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