10.Longitudinal vibration of propulsion shafting systems is often excited by the variable thrust
developed by the propeller due to the non-uniform wake pattern in which it operates. The
predominant periodic component of the thrust developed by a propeller occurs at blade-rate
frequency, i.e., the number of propeller blades times the rotational frequency of the shaft. For a four-blade propeller running at 60 rev/min, what is the predominant periodic frequency that excites
the longitudinal vibration of the propulsion shafting systems?
(A)1 Hz
(B)2 Hz
(C)3 Hz
(D)4 Hz
36.What does the International Safety Management (ISM) Code stand for?
(A)The international management code for safety operation of ships and accident prevention (B)The international management code for safety operation of crews and accident prevention (C)The international management code for safety operation of ships and pollution prevention (D)The international management code for safety operation of crews and pollution prevention
23. Whichdevice is used in a diesel engine to inject a metered quantity of lubricating oil into the
cylinder as the piston ring pack passes the injection points? (A) Lubricator (B) Camshaft (C) Crosshead (D) Piston rod
4. Crankcase and cylinder jackets are separated from each other by a partition, which
incorporates the ____________ through which the piston rods pass
(A) cylinder cover
(B) cylinder liner
(C) cylinder block
(D) stuffing boxes