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Propulsion and propeller — Engineering, Mashit 30

15 questions on propulsion and propeller, from the Engineering exam of Mashit 30. Gearbox, shaft, pitch, diameter and thrust. Every question is shown with its correct answer, as in the official question pool.

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Questions on Propulsion and propeller

  1. What transmits most of the propeller's thrust to the vessel? The tapered end of the shaft.
  2. What will be the effect of replacing the propeller with one of greater pitch? The load on the engine will increase.
  3. How is the vessel's movement changed from "ahead" to "astern"? By reversing the direction of rotation of the propeller shaft.
  4. What is the function of the zinc anode fitted to the bottom of the vessel? To prevent electrolytic corrosion of metal parts in the water.
  5. What does the blade area of a vessel's propeller affect? The amount of thrust delivered to the vessel.
  6. What is the main purpose of the "key" at the end of the propeller shaft? It is used mainly to lock the propeller to the shaft and keep it secure.
  7. What is the main function of the gearbox on most vessels? To allow the direction of rotation of the propeller shaft to be changed.
  8. What is the function of the thrust bearing in the propeller shaft system? To transmit the propeller's propulsive force to the vessel.
  9. What will happen if we replace our vessel's propeller with one of the same diameter but a smaller pitch? The load on the engine will decrease.
  10. What does the pitch of a propeller indicate? The theoretical distance the vessel advances in each revolution.
  11. What does the diameter of the propeller mainly affect? The amount of thrust delivered to the vessel.
  12. How is the engine's gearbox lubricated? With gearbox oil.
  13. How is most of the torque transmitted from the shaft to the propeller? By the tapered (conical) end of the shaft.
  14. What signs may show that the propeller shaft is out of line (misaligned)? All of the above.
  15. What is the purpose of the stern gland (stuffing box) on the propeller shaft? To stop sea water entering the vessel through the opening where the propeller shaft passes out to the sea.

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