90 



UNITED STATES COAST GUARD 



With the cross curves shown below, a displacement of 10,000 tons and a KG 

 draw the curve of statical stability for of 19 feet. Show all work. 



TABIE OP SIHE3 



15" - .25 

 30* - .50 

 45* - .71 

 60» - .87 

 75" - .97 

 SO" -1.00 



On a vessel at sea it is desired to 

 check the metacentric height by em- 

 ploying the empirical formula: 

 .44 B 



T = 



V GM 



.... where "B" is the vessel's beam of 

 50 feet and "T" is the full period of 

 the vessel's roll which was carefully 

 timed and an average value of 15 

 seconds obtained. 



Required: The GM as given by using 

 the formula. 



Note: Full period means starboard to port 

 then back to starboard (all included). 



Shown below is a statical stability 

 curve. Copy this curve and show the loss 

 of righting arm due to the center of 

 gravity being 2 feet off the center line. 

 Indicate the angle to which the vessel 



will list and the righting arm remaining 

 at 45° angle of inclination. 



A vessel of 6,000 tons displacement 

 carries two slack tanks of carbon 

 tetrachloride (sp. gr. 1.6). The tanks 

 are each 40 feet long and 25 feet wide. 

 What is the reduction in metacentric 

 height due to free surface with vessel 

 in sea water (sp. gr. 1.025) ? 



Note: The reduction in metacentric height due 

 to free surface may be determined by the for- 

 mula _rlb3_ where: r is the ratio of the specific 



12 V 

 gravity of the liquid in the tank to the specific 

 gravity of the liquid in which the vessel ia float- 

 ing. 



IbS is the moment of inertia of the tank. 



12 



V is the volume of displacement. 



What is the purpose of "blow-out 

 plugs" in the longitudinal bulkheads of 

 refrigerated spaces on vessels? 



ANOUS OP INCLINATION 



