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Maintaining Your Boat

Vessel Maintenance

A well-maintained vessel is basic to safety at sea. Poor motor maintenance alone is responsible for thousands of calls for assistance each year.

This section covers maintenance techniques and schedules that skippers should be aware of to keep their vessels in a reliable and seaworthy condition.

Engine Service


Manufacturers usually recommend a service by a specialised workshop at least once a year, even if you use the motor very little. This ensures that vital internal parts, like the water pump, get looked at. If you work your motor hard, then you should have the gearbox oil changed every three months.

Electrical System

Electrical systems on boats commonly fail through corrosion.

  • Keep all electrical systems clean and corrosion free by frequent inspections.
  • Spary terminals, electrical connectors, etc. with a corrosion-retarding agent. Keep all electrical fittings dry.
  • Check the lights are working even if you expect to be out only during the daylight hours.




One of the most common reasons for calling on sea rescue is a flat battery. Batteries deserve a lot of attention at regular intervals.

  • Use a genuine marine battery - your motor's handbook will tell you what capacity. Check it and charge it reguarly. If the battery does not hold its charge, it should be tested or replaced.
  • Batteries should always be secured with brackets within a ventilated container.
  • Terminals and cables must be kep clean, and terminals greased.
  • Terminals and connections must be tight and secure.
  • Top up battery cells with distilled water and check each cell with a hydrometer.
  • Turn off the power to the charger before disconnecting the charging pads. This may prevent an explosion.


Spark Plugs


With modern engines, spark plugs generally last longer. If they fail, then cleansing them is not very likely to bring them back to life. Carry a spare set of new plugs and a plug spanner.





Water Pump

Outboard water pump impellers are normally changed at the annual service. If you have been operating in the shallows and stirring sand, consider changing more often.

Make sure water is being discharged from the exhaust system or telltale when started.

Regularly check for water leaks.


Gearbox Oil


Bleed a little oil from the drain screw in the gear case - if water appears, or if the oil looks milky, take teh motor to a service centre.






The rubber bushing of an outboard or stern drive's propeller can fail, especially if it has hit sand or rocks. Some older models use a shear pin instead to protect the shaft.

Carry a spare shear pin, if appropriate, and a spare propeller - perhaps a second-hand one.

Keep shafts and props clean and in good working order. This includes removing the propeller., hammering out any bends, and filing any jagged bits smooth.

Snagged fishing line wrapping around the outboard leg propeller shaft can destroy the gearbox seals and allow water in. Water in the gearbox will eventually cause it to fail. Remove the propeller regularly to check for fishing line - or any time you think you might have hit a line.






Routine Maintenance


Before each trip

  • Test navigation lights.
  • Check the bilges are clean and dry, investigate the sources of leaks.
  • Check that the bilge pump works.
  • Check that the bungs are not worn and that the washer is in good condition.
  • Test steering gear for stiffness.

After each trip

  • As you winch the boat onto the trailer inspect the wire, webbing or rope for wear.
  • Flush the engine with fresh water and wash down its exterior.



  • Ensure the trailer winch wire is all well oiled to prevent corrosion.
  • Oil steering gear cable with the correct lubricant, check hydraulic fluid levels.
  • Check freeing ports (deck drain flaps) for positive opening and closing action.
  • Check condition of all safety equipment (the detail of this is included in the safety equipment section) before securely storing it.
  • Inspect the boat for rubbish - it is especially important to remove stray metal items from an aluminium boat.
  • Check berthing lines and anchor rope for wear.
  • Check that all auxiliary systems (anchor winch, windscreen wipers etc) are functioning.



  • Inspect through-hull fittings for corrosion and water tightness; ensure sea cocks are working and check the condition of hoses and clamps attached to them.
  • Check that important fittings (for example cleats, engines bolts, guard and grab rails) are still securely attached
  • Have the LP gas system serviced.
  • Have any 240 volt system checked.
  • Check aluminium hulls for corrosion and fatigue cracks, check fibreglass for blistering and impact cracks.
  • Check anodes for erosion, replace when about 40 per cent aroded.


Acknowledgement: Maintaining Your Boat > Source Government of Western Australia Department of Transport