FLOATING AND RAFTING 



361 



boom, "bracket" boom, "fin" boom and "barge" boom. The 

 first three are single-log limber booms, the names referring to 

 the manner of attachment one to the other; the bracket boom is 

 a stiff boom several logs wide, and the fin and barge booms are 

 either stiff or limber. 



Plug booms, also known as "plug and knock down" booms, 

 consist of logs fastened end to end with short pieces of rope or 

 withes whose ends are passed through holes bored in the ends of 

 the boom and securely fastened by plugs driven after them. 



Booms of this character are serviceable as a makeshift when 

 stronger fastenings are not available. 



DOG AND CHAIN 



CLEVIS AND RING 



Fig. 106. — The Methods of fastening Boom Sticks with Chains. 



Sheep-shank booms are temporary booms fastened together by 

 rope, a half hitch being made around the ends of the logs. They 

 are used for repairing breaks in other booms where rope is the 

 only equipment available. 



Chain booms are the common form of limber boom in use to- 

 day. Short chains are used to connect the logs, and are fastened 

 in several different ways: (i) by a chain and dogs; (2) by a ring 

 and toggle; (3) by a clevis, making an endless chain. The latter 

 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- 



