The effect of a rough propeller on the vessel’s fuel consumption is big. The cost of remedying a rough propeller is very minor. Remedies for a rough propeller are not only simple and quick to execute, they also represent a fast, high return on investment.
Propellers invariably become rougher during service. Different causes (like marine fouling, corrosion and mechanical damage) tend to work together, with each source of roughness complementing the other sources and accelerating the propeller’s decline in overall smoothness.
A rough propeller results in a fuel penalty for the ship. How large that penalty is depends on the degree of roughness. Based on information available, it can be seen that propeller surface roughness from fouling and surface deterioration can cause a fuel consumption penalty of somewhere between 5 and 15 per cent.
At current fuel prices, the fuel penalty from a rough propeller adds up to a high cost. Conversely, the savings attainable from keeping a ship’s propeller clean and smooth are significant.
Propeller maintenance best practices
Badly done polishing with a polishing disc or grinding wheel can in itself create a rougher surface than that of the new propeller, leaving scratches which not only increase the propeller’s roughness but also invite easier attachment of fouling organisms.
Cleaning a propeller once every month or every two months would in many cases be optimum. If carried out this frequently, cleaning with a relatively soft tool is adequate to keep a well-maintained propeller smooth enough for maximum fuel savings.
Thanks to its network of offices and service stations, Hydrex can offer propeller cleanings on a worldwide basis. These operations are carried out using underwater equipment designed and developed in-house specifically for propeller maintenance. Hydrex combines this service with underwater inspections where this is economically advantageous to the shipowner or operator.
For more information on the advantages of propeller cleanings, please click on this link.
In the interests of sustainable shipping and a healthy marine environment, Hydrex has created a series of White Papers, a quarterly Journal of Ship Hull Performance and a website, www.shiphullperformance.org, to make this information available.