Numerous mechanical and electrical systems are installed on board a ship and they require maintenance. Proper maintenance of a ship has significant impact on overall technical performance and energy efficiency of the vessel.
A ship is usually scheduled once a year for maintenance in a port or a shipyard, the circle of maintenance and continuous survey of the ship is of 5 years, each year the Classification Society survey the ship on float and each 2.5 year the Classification Society survey the ship in dry dock. However, some maintenance is required between such planned maintenance periods. This includes both routine/preventive maintenance and repair of breakdowns (at least temporary repair until the ship reaches the next port). On-board maintenance is usually done by the crew, but the shrinking size of crews reduces the availability of the crew for maintenance work. A large ship may have less than two dozen seamen on board, and that includes the captain and the caterers. This limited crew operates the ship around the clock.
In order to facilitate maintenance, a ship must carry spare parts on board. The amount of spare parts is determined by the frequency of port calls and whether spares and equipment are available in these ports. Large and expensive spares that cannot be shipped by air, such as a propeller, may pose a special problem and may have to be prepositioned at a port or carried on board the vessel.
Ship maintenance operations and management are fundamental for energy efficient operation of its machineries and systems. Deterioration of ship systems’ condition takes place due to normal wear and tear, fouling, miss-adjustments, long periods of operation outside design envelopes, etc. Consequently, equipment downtime, quality problems, energy losses, safety hazards or environmental pollution may result. The end outcome is a negative impact on the operating cost, profitability, customer satisfaction and probable negative environmental impacts. Thus, good maintenance is in line with good performance and energy efficiency.
To facilitate good ship maintenance despite the lowering number of crews over time, decision support tools for condition monitoring are frequently used. Also, third party maintenance contracts could be made so that external specialized organizations look after important ship-board assets (e.g. engines). The increase in data communication between ship and shore is an enabling technology to provide support to ship-board staff by the shoe-based staff.
The planned maintenance is organized based on makers prescribed maintenance frequency and a set number of spares is supplied to vessel prior to the scheduled maintenance date. A computer operated maintenance database is maintained on board and in the shore-office synchronized to upkeep all the maintenance info and spare parts availability etc. including maintenance procedure.
The breakdown maintenance is performed upon failure of a component or machinery. Though this procedure is cost saving but in the long run it may pose the vessel to undue delays and uncertainty of the schedule.
The Condition monitoring is another kind of diagnosis system of the machineries by which a decision may be made if a maintenance should be carried out by feeling its’ running condition e.g. Vibration, load current, operation temperature etc. This is a cost saving procedure in respect to planned maintenance, and a maintenance requirement is assumed prior to a breakdown, however, the condition monitoring requires very highly skilled engineers to diagnose a fault (MariEMS 2017).