DieselShip's Online Content Library

Q1. (a) Describe the properties of EACH of the following alloys used in marine engineering, giving a practical example for which, EACH are suited:

(i) cupro-nickel: (2)

(ii) white metal: (2)

(iii) titanium. (2)

(b) Apart from corrosion and erosion resistance, describe the properties of EACH of the following for use in the manufacture of large propellers:

(i) nickel aluminium bronze: (2)

(ii) stainless steel. (2)

Q2. With reference to pneumatically operated control valves:

(a) state the reason for fitting valve positioners; (4)

(b) with the aid of a sketch, explain valve hysteresis and how it affects the process; (3)

(c) describe how the design and routine maintenance can limit hysteresis. (3)

Q3. With reference to propeller shaft support bearings:

(a) Describe, with the aid of a sketch, the operation of a tilting pad shaft bearing, indicating how the oil pressure is distributed. (5)

(b) Explain why this type of bearing evolved, stating its advantages over plain bearings. (5)

Q5. With reference to multi-tubular heat exchangers, explain how EACH of the following contribute to satisfactory performance:

(a) tube wall thickness;(2)              (b) dense population of tubes in the tube plate;(2)

(c) tube materials selection;(2)       (d) coolant flow rates;(2)

(e) unimpeded passage of coolant at entry and exit from the tubes. (2)

Q4. With reference to centrifugal pumps and pumping systems:

(a) explain, with the aid of a diagram, the distinction between Net Positive Suction Head available (NPSHa) and Net Positive Suction Head required (NPSHr); (8)

(b) explain how the NPSHa may be increased by design. (2)

Q3. With reference to a keyless propeller designed for hydraulic (wet) fit and withdrawal:

(a) describe, with the aid of a sketch, how the propeller is fitted to the tail shaft; (6)

(b) state TWO advantages compared to a dry fit; (2)

(c) explain how the thrust is transmitted without the use of a key and keyway. (2)

Q7. With reference to air compressors for general service use:

(a) Explain the principle of operation of a screw type compressor (4)

(b) Explain the advantages of screw compressors over reciprocating compressors in terms of running and maintenance. (6)

Q8. Describe the inspections and tests that should be carried out to ensure satisfactory condition and operation of the ship’s firefighting equipment.