By
Rebecca Gibson |
A study of the effects of anti-fouling coatings shows significant impact on ship efficiency.The role played by hull coatings in determining the fuel-efficiency of ships has come under the spotlight in a new study by Eniram. Research by the Finnish company to determine key fouling characteristics studied the hulls of around 60 vessels over 38,000 sea days operating in different regions of the world. The study findings identified that in certain areas where fouling was greater, the energy consumption of the vessel increased significantly faster than in other areas – for example, cruise vessels operating in the Caribbean were worst affected.
The study was also able to show the variable impact of hull fouling on vessels moving across different regions, says Henrik Dahl, CTO and co-founder of Eniram. “When sailing across the Atlantic, for example, the friction from hull fouling actually reduced for a time, with fouling even decreasing before resuming the build-up again,” explains Dahl. “Being able to get such an accurate insight into the vessel’s hull fouling condition from energy consumption data collected is vital for maintaining vessel performance to economically feasible standards. It helps to optimise the hull cleaning strategy, such as coating decisions or possible underwater cleanings.”
Analysing vessel performance is often a challenge due to the lack of accurate performance data that can be trusted when operating in a dynamic environment. Weather, waves, currents and sea state are constantly changing and influencing performance. “Eniram has developed an advanced system that enables energy consumption to be analysed according to factors such as as weather, water depth and fouling,” say Dahl. “This information allows for very accurate analysis to be carried out regarding the hull friction, for example. Cruise vessels often operate in high fouling growth regions and their performance levels and energy consumption can be severely affected by added hull resistance. Knowing the additional energy consumed by fouling, cruise operators are able to decide on the most appropriate corrective actions.”
But knowing the effect of the fouling alone is not enough. Brushing can help hull cleansing but can also lead to damage to the protective coating. Detailed information on a ship’s energy consumption helps monitor any changes due to fouling and act as an early detector of cleaning needs or possible post cleaning damage, says Dahl. “We work very closely with customers in helping them to monitor their vessel and fleet performance. This includes monitoring of any changes in hull friction and fouling. We have analysed different coatings on vessels to identify the most suitable coating for a specific operating profile. Our data has also helped operators to monitor and verify whether the coating manufacturer’s performance claims are real.”
The analytical reports help customers decide if and when to brush to minimize propulsion energy consumption and emissions. Eniram’s customers are using this kind of intelligence to realise substantial savings in their operating costs and the results are impressive, says Dahl. “For the operating profiles of the vessels studied, these savings were on average 2 per cent of their overall propulsion fuel consumption. In extreme examples, we have witnessed savings of around 10 per cent.” For owners and operators, this is a strong incentive to collecting and analyse data on hull fouling.