SEM300
EMRI SEM300 — Autopilot, Heading Control & Track Control System.
Inspector Detail
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Common issues
- Heading sensor (gyrocompass/GPS compass) interface faults causing erratic autopilot behavior
- Rudder feedback unit misalignment causing a steering offset
- Control panel display or backlight failures
- Software/parameter settings lost after a power interruption if backup memory fails
- Changeover between autopilot, manual, and non-follow-up modes not functioning cleanly
- Alarm system not annunciating on loss of heading signal
Inspection checklist
- Verify heading sensor input against the magnetic/gyro compass
- Check rudder feedback unit alignment against the actual rudder angle indicator
- Test changeover between autopilot, hand steering, and non-follow-up modes
- Test all alarm functions - off-course, power failure, sensor failure
- Check backup power supply/battery condition
- Confirm control panel and display function, including backlight
- Verify performance mode settings are appropriate for the vessel and sea state
Service intervals
| Rudder feedback alignment check | at each dry-docking or after any steering gear work |
| Backup battery replacement | typically every 3-5 years, per the maker's stated interval |
| Software/parameter backup verification | annually or after any system update |
| Alarm function test | per the SOLAS steering gear test schedule, before departure and periodically |
Typical wear limits
| Rudder feedback offset | should track true rudder angle within the tolerance stated in the maker's manual - not a generic figure across systems |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Control panel unit
- Rudder feedback (angle transmitter) unit
- Backup battery pack
- Interface/comparator board, if the system is modular
Safety
- Loss of steering control while underway - crew must be drilled on immediate changeover to manual/emergency steering
- A false or delayed alarm on sensor failure can mask a developing steering fault
- Do not disable alarm functions to silence nuisance alarms without addressing the underlying fault
Class survey
Autopilot/heading control systems interfacing with steering gear fall under SOLAS V/19 and the steering gear testing requirements of SOLAS V/26 - class/flag verifies changeover to manual steering and alarm functions at each steering gear test before departure and at periodic survey; keep test log records available.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Verify potentiometer kit replacement intervals: RFC/RFU systems with sliding contact require replacement every 5 years maximum. RFC360-D Hall sensor versions have 10-year service life minimum. Test analog output signals (±12Vdc, ±15Vdc) from feedback units for noise and drift; confirm no mechanical wear in uni-ball links or belt drives on RFU/RFB units.
Verify port-to-starboard rudder movement completes within 28-38 seconds per SOLAS requirements. Test RCU servo boxes (RCU10-440, RCU20-440, RCW10-440) for proportional/bang-bang control accuracy. Confirm power supply voltages at KSA control boards are stable (+/-12Vdc, +/-15Vdc, 100Vac). Check no hydraulic lock alarms on torque motors; verify coupling condition.
Verify WMS (Work Mode Station) PLC firmware version matches documented baseline. Test RSR relay expansion boxes function correctly in multi-rudder systems. Confirm backup power supply (SAB.10/SAB10-230) voltage levels and capacitor condition. Verify hot standby redundancy switches operate without glitches; test fail-over response time.
Test RIB511 and RIF511 rudder angle indicators for calibration accuracy against actual rudder position sensors. Verify analog output (1-0.1mA) continuity from indicators to autopilot control panels. Confirm SEM300 TFT display brightness (800 cd/m²) is within specification and visible from all bridge positions. Check all 4 control panel connections have consistent readouts; verify alarm annunciation.
Identify installed steering gear brand (Mitsubishi, Kawasaki, ABB, Hatlapa, Hitachi) and confirm correct RCU/ACU model variant is installed. Verify hydraulic pump configuration matches system design: 3-pump systems use RCU10/RCW10 models, 4-pump LNG systems use RCU20-440. Test proportional vs. bang-bang control mode operation per gear manufacturer specifications. Inspect hydraulic hose condition and pressure relief valve settings.
Type-general inspection and maintenance points for this equipment category — not model-specific.
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