98 



UNITED STATES COAST GUARD 



What is the purpose of the copper 

 wire frequently fitted to stay turn- 

 buckles? 



Sketched is a pressure-vacuum valve 

 such as is found on many tank vessels. 

 Describe briefly the care and inspection 

 such a valve requires. 



COPPER VIRE 



WP7777/7 



What is the purpose of a thrust 

 block? 



What type bearings are usually em- 

 ployed for thrust blocks? 



How are the foundations for thrust 

 blocks constructed? 



Would you expect "hogging" or "sag- 

 ging" stresses to be more severe on a 

 vessel with machinery aft in the full 

 load condition? 



Where wooden doors are permitted in 

 a superstructure, how must the doors 

 be constructed to meet the strength re- 

 quirements? 



On the illustration shown, identify 

 "A," "B," "C," and "D." 



If, in heavy weather, you notice 

 buckling in the midship deck plating of 

 your vessel, 



(a) what would it indicate? 



(b) What measures could you 

 take? 



What type of stress do the deck beam 

 brackets of a transversely framed 

 vessel resist? 



