52 



thick asphalt may be applied, to prevent the penetration of moisture; 

 below water line the access of borers can be prevented by covering 

 tightly with sheet copper. 



Bracing, Ribbing, etc. The only safe way is to have all bracing, 

 ribbing and other construction attachments well above high water 

 (Plate 11, Fig. 2). Where this cannot be done, dapping the piles, which 

 exposes untreated wood, should be prohibited, (Plate 12, Fig. 2), ex- 

 cept where it is absolutely unavoidable, letting necessary cutting or 

 framing be done, as far as possible, on the pieces to be attached to 

 the pile, since they are cheaper to renew. The braces, ribbing and 

 other attachment members should be creosoted if they will be exposed 

 to borer attack, and all boring and framing which can possibly be 

 done in advance should be made before the members are creosoted. 

 Otherwise all such holes or framing cuttings should be well swabbed 

 with hot creosote before putting the parts into the construction. All 

 holes for bolts or pins should be bored not larger in diameter than the 

 bolt or pin, to insure a driving fit. This will prevent borers from en- 

 tering the bolt holes, so far as it is possible to provide against it. 

 (Plate 12, Fig. 1; Plate 13; Plate 14.) 



Fender Lines. Fender lines are always constructed of wooden 

 piling, usually untreated in this region but sometimes treated. Con- 

 nections to treated piling below the water line, where such connec- 

 tions expose untreated material, are dangerous. Bolt and spike holes 

 provide a ready means for borers to enter. Where it is necessary to 

 bore holes in creosoted fender piling the holes should be bored for a 

 driving fit, as above indicated for bracing. 



Repairing Damaged Piles 



When a treated pile is damaged it should be immediately repaired. 

 Holes should be plugged with creosoted material, and where repairs 

 cannot be made in this way the damaged place should be covered with 

 sheet copper. The Board of State Harbor Commissioners have re- 

 cently been filling such holes, as well as those of the initial attacks 

 of Limnoria working in them, with cement mortar. It is too early to 

 judge the effectiveness of the method, but it looks promising. 



\ 

 Removing lireeding Grounds 



As a means of removing the breeding grounds of marine borers, 

 not only should the use be avoided, so far as practicable, of untreated 

 wood in waters infected by marine borers, but shores should be kepi, 

 clean of drift-wdbtf or other wooden debris, and pile stumps and similar 

 debris removed thoroughly from the sites of dismantled or. abandoned 

 structures. This seems to be a practical way of reducing progressively 

 the severity of the annual attacks which follow the breeding season, 

 in the fall of each year, in this harbor. This matter was emphasized 



