Rudder drift and overheating steering gear near the pilot station
A 12,000 GT product tanker is proceeding at 8 knots in coastal waters, two hours from the pilot station. The steering gear is a two-ram electro-hydraulic type. One pump is running and the second is on standby. With the helm amidships, the rudder angle indicator drifts about 2° to port over 20 minutes; the autopilot then applies corrective helm and the ship yaws slightly. Hydraulic oil temperature is 68°C against a normal 45°C. Pump discharge pressure fluctuates between 65 and 90 bar, and the return filter differential pressure is high. No external oil leak is visible and the reservoir level is normal. The bridge has reported that steering feels “soft” and slower than usual. The master wants to continue to the pilot station without delay. The engine room must decide what to do immediately, what to troubleshoot, and whether to inform the bridge that steering capability is degraded.
1. What immediate actions would you take and what would you tell the bridge?
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Immediate action:
- Tell the bridge now that steering response is degraded. The master needs that information to reduce speed, increase under-keel clearance where possible, and prepare anchor/emergency steering.
- Change to the standby steering pump and observe rudder response, pressure and temperature. If the standby pump restores steady pressure and the drift stops, continue at reduced speed with continuous monitoring and bridge agreement.
- If drift continues, do not press on to the pilot station at 8 knots. Recommend reducing speed and preparing to anchor in safe water; steering is a primary control system.
- Check that the autopilot is not masking the fault by continuous corrective helm. Switch to hand steering for a direct comparison.
- Record times, pump pressures, temperatures and bridge communications. The judgement is that a 2° drift in 20 minutes is small in angle but significant in cause: it can be air, internal leakage or a sticking control valve, and it may worsen quickly in confined waters.
2. Set out a troubleshooting sequence for the symptoms, naming the likely causes and the checks that distinguish them.
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Use the symptoms together:
- High oil temperature plus fluctuating discharge pressure and high return-filter differential suggests a restriction or internal leakage, not simply ‘old oil’. A clogged return filter raises back-pressure and temperature; a worn pump or relief valve passing oil generates heat and unstable pressure.
- Check the return filter element and suction strainer; inspect for debris. If the filter is collapsed or blocked, renew it and test again.
- Check for air entrainment: pump suction joints, reservoir level, and bleed points. Air causes soft, hunting steering and pressure fluctuation.
- Compare pump case drain and current between pumps; a worn pump usually shows higher case flow and lower holding pressure.
- Verify the relief valve setting and that the bypass/isolation valve is fully closed; do not adjust the relief valve to compensate for a worn pump.
- Check rudder-angle feedback calibration; a drifting indicator with no actual rudder movement would point to instrumentation, but the yaw and ‘soft’ feel suggest a real hydraulic fault.
3. What decision would you recommend on continuing to the pilot station, and what emergency-steering checks would you require?
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Decision:
- If the standby pump gives steady pressure, normal temperature and no rudder drift during a controlled test, proceed at reduced speed to the pilot station with the bridge informed and the second pump ready. Keep the engine room manned and monitor every 15 minutes.
- If drift, overheating or pressure fluctuation persists, stop or anchor in safe water and repair before continuing. Do not rely on the autopilot to hide a hydraulic fault.
- Test emergency steering according to the ship’s procedure, including communication between bridge and steering flat and operation from the emergency power supply where fitted. Confirm the time to change over and the rudder response.
- Inform the master in writing if steering capability is degraded; the master decides on passage, but the engineer must give a clear technical recommendation. Record the event and notify the company.