• Damage to the rudder plating (cracks, holing) from grounding, collision, or impact, allowing sea water to enter.
• Corrosion/ wastage of the rudder plating, creating holes/ leaks.
• Failure/ leakage of the rudder stock gland or the rudder-to-stock connection, allowing water to enter.
• Damage to the rudder palm/ sole plate or the welds.
• Failure of the rudder's internal structure/ stiffeners allowing water ingress.
• A defective/ missing rudder drain plug or inspection cover.

• A change in the rudder's weight/ balance - the rudder may feel heavier or the steering may be affected (the rudder is heavier to move).
• A change in the rudder's vibration/ noise - a flooded rudder may vibrate or hum differently.
• Water/ air escaping from the rudder drain plug or inspection cover (if accessible).
• A change in the vessel's steering/ manoeuvring characteristics.
• A visible leak/ water at the rudder stock gland.
• In some cases, a change in the vessel's trim/ list (if a large amount of water enters).
• The rudder may be detected as flooded during dry-dock inspection (by tapping/ weighing or by draining).

(i) Rudder examination:

• In dry dock, the rudder is examined externally (visual) for cracks, corrosion, wastage, holing and deformation.
• The rudder is checked for flooding by tapping (a dead/ hollow sound), by draining the rudder (opening the drain plug and checking for water), or by weighing/ ultrasonic thickness.
• The rudder stock, coupling, pintles, gudgeons and bearings are examined for wear, corrosion and damage.
• The rudder is checked for correct alignment and freedom of movement.
• NDT (dye-penetrant, ultrasonic) is carried out on suspect areas.
• The findings are recorded and the rudder is repaired/ renewed as required.

(ii) Rudder repair:

• If the rudder is flooded, the water is drained (via the drain plug) and the rudder is dried.
• Cracks/ holes in the plating are repaired by welding (after cleaning and preparing the area), and the welds are inspected (NDT).
• Wasted/ corroded plating is renewed (cut out and replaced with new plate of the correct material/ thickness).
• The internal structure/ stiffeners are inspected and repaired.
• The rudder is pressure-tested/ leak-tested (e.g. by filling with water/ air and checking for leaks) to confirm it is watertight.
• The rudder stock, coupling, pintles and bearings are repaired/ renewed as required.
• The rudder is re-fitted and the steering gear is tested.
• The repair is carried out to the maker's/ Class requirements and surveyed as required.