CHIEF ENGINEER Unit 15 Periodical Dry Docking Q4 Answer

  1. With reference to the periodical routine dry-docking of a vessel:
    (a) state FOUR reasons for dry-docking;
    (b) outline THREE methods of testing a hull for watertight integrity.

(a) Four reasons for dry-docking a vessel (4 marks)

  1. Inspection of the underwater hull – checking for corrosion, fouling, or structural defects.
  2. Cleaning and painting – removal of marine growth and application of anti-fouling or protective coatings.
  3. Inspection and repair of underwater fittings – including sea chests, overboard discharges, stern tube, and rudder.
  4. Survey requirements – classification society and statutory surveys require periodic dry-docking for safety certification.

(b) Three methods of testing hull watertight integrity (3 marks)

  1. Hose or water jet test – external high-pressure water directed at hatch covers, doors, or suspected areas to detect leaks.
  2. Chalk or light test – chalk applied to seating surfaces or light shone through from the opposite side to check sealing.
  3. Ultrasonic test – ultrasonic transmitter placed inside compartment; detector outside identifies leaks through seal gaps.