- Describe the procedure that should be followed if an outboard motor has been submerged in sea water.(10)
Procedure if an Outboard Motor Has Been Submerged in Sea Water (10 marks)
When an outboard motor is accidentally submerged, immediate action is vital to prevent corrosion, electrical failure, and internal damage. The following steps should be carried out as soon as possible after recovery:
1. Recovery and Initial Rinsing (1 mark)
- Retrieve the motor as quickly as possible to minimise saltwater corrosion.
- Do not attempt to start the engine. Starting it before cleaning may draw salt water into the cylinders.
- Immediately rinse the exterior thoroughly with fresh water to remove all traces of salt and sand.
2. Removal of Cowling and Drainage (1 mark)
- Remove the engine cover (cowling) and drain any seawater trapped inside the casing.
- Remove spark plugs to allow water to drain from the combustion chambers.
- Tilt the engine to facilitate complete drainage from all cavities.
3. Flushing and Cleaning (2 marks)
- If possible, immerse the powerhead in fresh water or flush with clean fresh water to remove salt deposits.
- Spray or rinse all electrical components, linkages, and metal parts with fresh water to neutralise salt.
- Pay special attention to the starter motor, ignition coils, carburettor, and fuel system.
4. Disassembly and Drying (2 marks)
- Strip down components such as the carburettor, starter motor, and electrical connectors for inspection.
- Dry components using low-pressure compressed air or gentle heat (never open flame).
- Spray all exposed metal parts and electrical terminals with a water-displacing lubricant (e.g. WD-40).
5. Internal Cylinder Protection (1 mark)
- Pour a small quantity of clean lubricating oil or fogging oil into each cylinder through the spark plug holes.
- Turn the engine over manually several times to distribute the oil and expel any remaining moisture.
6. Fuel System Draining and Flushing (1 mark)
- Drain and discard any contaminated fuel from the carburettor, lines, and tank.
- Refill with fresh, clean fuel and check for saltwater contamination in filters.
7. Electrical System Inspection (1 mark)
- Check battery terminals, fuses, starter solenoid, and ignition leads for corrosion.
- Clean and dry all connections, applying anti-corrosive grease or protective spray before reassembly.
8. Reassembly and Test Run (1 mark)
- Reassemble the motor and fit new spark plugs.
- Connect to a freshwater flushing tank or hose attachment and start the engine.
- Run the engine for 10–15 minutes to ensure smooth operation and complete removal of moisture.
9. Post-Test Maintenance (1 mark)
- After running, stop the engine and inspect for oil emulsification (milky appearance) or irregular running.
- Change the gearcase oil if water contamination is suspected.
- Re-grease all linkages and pivot points.
10. Record and Monitor (1 mark)
- Make a log entry of the submersion, inspection, and actions taken.
- Monitor the motor during subsequent operations for signs of corrosion, misfiring, or bearing noise.