1. Preparation: With the vessel in dock and the rudder stock accessible, note the rudder angle and secure the rudder in the midship (or a marked) position; dewater and wash down the rudder and sternpost area.
2. External visual examination: Examine the rudder plating, welds and fairing for cracks, corrosion, pitting, wastage, buckling and deformation over the whole blade surface (both sides once access allows) and the edges; check the leading/trailing edges and the rudder palm/sole plate.
3. Check for flooding of a hollow rudder: Tap the rudder blade to detect a dead/ solid or hollow (half-empty) sound, weigh the rudder if provision is available, or use ultrasonic thickness; a hollow rudder is often detected by draining the rudder drain plug - water or air coming out indicates internal water/ flooding - or by internal inspection where an inspection cover exists.
4. Check the rudder stock: Expose the rudder stock at the palm/top; examine for corrosion, pitting, cracks (particularly at the palm weld and at the top of the blade), and check the rudder stock to hull gland for leakage and fretting.
5. Check the rudder carrier/gland and rudder seal: Examine the packing/gland for tightness, the lower and upper rudder carrier bearings and the stock support.
6. Check rudder pintles and gudgeons (with bearings): Remove/ lower or examine the pintles for wear, scoring, pitting and correct clearance; check the gudgeon pockets, and check the pintle/hinge line alignment; measure bearing clearances.
7. Check the rudder stock coupling/flange: Check bolts for tightness and the joint for fretting/corrosion; check the stop and the emergency-quadrant coupling.
8. Check rudder angle indicators/ tele-motor: Confirm the mechanical and electrical indication and the stops work; check the tiller/ quadrant and actuating linkage.
9. Check anti-singing and appendages, and check the rudder horns (if any), and the rudder to hull gap and freedom of movement.
10. Record all findings, measurements (wastage, clearances), and photography for the survey report and repair specification.

(i) Relief valve:

• Relief valves are fitted in the hydraulic system of a steering gear (or as specified) set to relieve at a pressure set to limit the pressure in the system to that which is safe, so as to prevent overloading/damage to the gear and to the hydraulic unit. SOLAS requires that relief valves be fitted on the arrangement to limit the pressure when the steering gear is stalled; the setting shall be not less than the max working pressure at which the steering gear is required to operate and not more than the nominal/ burst rating of the system; the valve must be so fitted that relief occurs without chattering and that the fluid escaping is returned to the header tank/reservoir. The valve capacity and set pressure must comply with the manufacturer/ Class approved values and the relief valve must be proved during testing.
• (Essentially: the relief valve protects the steering gear hydraulic system from over-pressure under stalled operation, set to a value between the operating pressure and the system safe limit, sized to pass the full pump flow, and returned to the oil header.)

(ii) Steering gear control:

• SOLAS requires that the main steering gear control and the auxiliary/emergency control be operated so that failure of one component does not make the other ineffective; they must be arranged so that a single failure in the control system (apart from the steering gear units) does not prevent both motor and the auxiliary from operating. The control system must be capable of being brought into operation quickly (within the required time, generally 45 seconds after failure at sea). The steering gear control system must have an audible and visual alarm on the navigating bridge for a component failure; redundancy is required (e.g. duplicated control circuits) so that a single failure in the control does not cause loss of all steering.
• Electric control: a failure of the controlling gear (controller) must not render the other ineffective; provisions for changeover between main and emergency control must be provided.

(iii) Electrical power circuits:

• SOLAS requires that the electrical power circuits of the steering gear be so arranged that a single fault in the power supply/power circuits of one steering gear will not cause a failure of the other; i.e., the power circuits to the two steering gear sets are fed from independent and duplicated power sources (main and emergency/ battery). The system must be fed such that the failure of one circuit (e.g. one motor circuit or one generator feeder) does not render the other steering gear set inoperative, and automatic switching/ reorganization ensures the steering remains available. Where a telemotor/ emergency steering is fitted, a separate independent power source is provided. SOLAS also specifies the number of power units and the time by which the emergency source must supply (e.g., 45 seconds) so the gear can be brought into operation.