362 



LOGGING 



wise of the boom, or by short poles fastened to the logs by means 

 of wooden plugs, chains or withes. Booms of this character are 

 stronger than single booms and are used on the upstream side 

 of splash dams for converging logs toward the sluiceway, and are 

 also used around storage areas and sorting gaps as runways 

 for men. 



The fin boom is often employed to change the course of logs 

 from one side of a stream to the other, or to guide them past 

 obstructions. It is especially serviceable on a navigable stream 



Fig. 107. — A Fin Boom. a. A movable fin boom both open and closed, b. The 

 arrangement of boom and fins for a i)crmanent fin boom. 



where permanent booms cannot be maintained, and in places 

 where it is not feasible to moor the outer end of the boom to a 

 crib or pile. The shore end must always be upstream. The 

 fin boom may be either limber or stiff, preferably the latter, and 

 may be permanent or temporary. It consists of a main boom to 

 which the ends of pole or plank fins are attached by chains at 

 regular intervals. When the boom must be opened and closed 

 at frequent intervals the outer ends of the fins, which act as 

 rudders, are connected by a rope or cable which passes around 

 a drum or power-winch located on shore, while on stationary 

 booms the fins are weighted at the ends to give them rigidity, 



