FLOATING AND RAFTING 
401 
form is used very commonly for towing purposes and for storage 
areas because the booms can be readily uncoupled. 
The bracket boom is a stiff boom made three or four logs wide. 
The logs are fastened together by short boards nailed cross- 
wise on the boom, or by short poles fastened to the logs by means 
of wooden plugs, chains or withes. They also are bound together 
with chains which encircle the boom. They are stronger than 
single booms and are used on the upstream side of splash dams 
Fig. 141. — A Fin Boom. a. A movable fin boom both open and closed. 
h. The arrangement of boom and fins for a permanent fin boom. 
for converging logs toward the sluiceway, and are also used 
around storage areas and assorting 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 obstruc- 
tions. It is especially serviceable on a navigable stream 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 has 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 fre- 
quent intervals the outer ends of the fins, which act as rudders, 
