(Contribution from the Yale School of i'orestry) 



TROPICAL AivERIC/N iOODS VOR TimABlJ-: WAT;rtFRONT STRUC 

 by Frederick F. .-'angaard 



TURES^ 



Unless ';:iven a preservative treatment, only a limited number of domestic 

 TiToods are adapted to uses that involve conditions favorable to the develop- 

 ment of wood-rotting fungi or to marine borer activity. Through effective 

 methods of preservative treatment, the life of domestic vroods under these 

 conditions can be effectively increased. A number of tropical woods, how- 

 ever, have been employed without treatment for such purposes over prolonged 

 periods and the question is raised as to the possibilities for making wider 

 use of these and other naturally resistant species. 



Under the sponsorship of the Office of Naval Research and the Bureau of 

 Ships of the De^-'artraent of the Kav/, the Yale School of Forestry has been 

 engaged since 19h7 in a study of the properties and i.b es of woods from the 

 American tropics. The scope of the over-all study includes determination 

 of mechanical properties, densit;'-, shrinkage, decay resistance, rate of 

 moisture absorption., resistance to vreathering, and the characteristics 

 of the wood in relation to seasoning, paint holding, machining, gluing, 

 and steam bending. Through arrangement with the 1?J'illiam F, Clapp Labora- 

 tories at Duxbury, llassachusetts, certain of these woods are being subjected 

 to exposure in infested waters to determine their resistance to marine borer 

 attack. Other tests are conducted on. selected woods at the Nevir York Naval 

 Shipyai'd to determine resistance to lire and abrasion and at the Institute 

 of Paper Chemistry, Appleton, Vifisconsin, to determine the chemical composi- 

 tion of certain of th'esewoods. : . 



The successful use of wood for durable water front structures involves, 

 first of all, the selection of species combining the requisite mechanical 

 properties to sustain applied loads with resistarxe to deterioration. 

 Decay is the principal agency of deterioration above the water line, whereas 

 sub-surface structural members are subjected to attack by marine borers in 

 infested waters. - Other forms of deterioration to vAich certain parts of 

 water front structures are exposed include weathering and mechanical wear. 

 In addition to the qualities of strength and resistance to deterioration 

 a v:ood showing low slirinkage would generally be preferred to another 

 characterized by high shrinkage values, not only from the standpoint of 

 dimensional stability of the structure, but also from the lesser warp 

 that would ordinarily accompany lower shrinkage. 



U-Ihe data presented in this paper were gathered as a part of a general^ 

 study of the properties of tropical woods being conducted in cooperation 

 with the Office of Naval Research and Bureau of Ships, U. S. Navy Depart- 

 ment, under Contract N6ori-Uh, Task Order XV, Project No. NR-330-001. 



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