Roughest hour – approaches to ship hull fouling management
Doctoral thesis, 2019

Submerged surfaces at sea are colonized by a high diversity of sessile (i.e. attached) life forms. As the merchant fleet capacity increases, responding to growth in demand for seaborne transport, so does the hull wetted surface area that is prone to colonization by these sessile organisms, i.e. marine biofouling. Such colonization leads to increased ship hull surface roughness, which results in both environmental and economic issues, namely fuel penalties and increased emissions to air. Improved maintenance of the hull would not only reduce these penalties, but also reduce emission of antifoulants and other paint components to the marine environment, as well as risks related to the transport of non-indigenous species on fouled hulls.

The work presented in this thesis aimed at improving current approaches to the management of ship hull fouling, which typically rely on a combination of fouling-control coatings and an in-water cleaning scheme. Knowledge on the adhesive strength of fouling to minimize cleaning forces, on the one hand, and evaluation of the hull condition and hull roughness penalties, on the other hand, are therefore central to the aim of this thesis.

The outcome of performed work supports a preventive approach to hull maintenance, e.g. gentle and frequent cleanings (hull grooming), or an alternative predictive approach, based on vessel performance and condition monitoring for detecting early forms of fouling. Tools are provided with potential to improve hull maintenance practices. These include minimizing cleaning forces applied during in-water hull cleaning through knowledge on adhesion strength of fouling (Papers I, III and IV), and more-accurate determination of the impact of fouling on vessel performance, namely by accounting for hull form effects (Papers II) or using a novel performance indicator that would be applicable in wider comparisons between vessels (Paper V). Seen as a whole, results indicate that the goal of minimizing the environmental and economic risks involved in hull fouling management can only be achieved through continued collaboration between different industry stakeholders, researchers, technology developers, authorities and policymakers, leading to an optimal path in development.

vessel performance

fouling control coatings

hull grooming

ship resistance

adhesion strength

in-water hull cleaning



turbulent boundary layer

Saga-building, Hörselgången 4, Chalmers Campus Lindholmen, Gothenburg - SWEDEN
Opponent: Dr. Kelli Zargiel Hunsucker (Ph.D.), Florida Institute of Technology, USA


Dinis Oliveira

Chalmers, Mechanics and Maritime Sciences, Maritime Studies, Maritime Environmental Sciences

Matching Forces Applied in Underwater Hull Cleaning with Adhesion Strength of Marine Organisms

Journal of Marine Science and Engineering,; Vol. 4(2016)p. 66-

Journal article

Effect of ship hull form on the resistance penalty from biofouling

Biofouling,; Vol. 34(2018)p. 262-272

Journal article

Towards an absolute scale for adhesion strength of ship hull microfouling

Biofouling,; Vol. 35(2019)p. 244-258

Journal article

Oliveira, D and Granhag, L (–). Ship hull in-water cleaning and its effects on fouling-control coatings. Manuscript submitted to Biofouling.

Oliveira, D, Granhag, L and Larsson, L (–). A novel indicator for ship hull and propeller performance: examples from two shipping segments. Manuscript submitted to Ocean Engineering.

The International Chamber of Shipping estimates that shipping transports around 90% of international trade. Even though large merchant ships constitute the most energy-efficient transport mode for cargo, the industry is one of the most challenging in terms of reaching Paris-Agreement climate goals in a fair and proportionate way. Other impacts of shipping on the environment, besides contributing to climate change and air pollution, include impact on water quality and transport of potentially harmful aquatic species across the globe.

One way to reduce the energy required to propel a ship across the oceans is to ensure underwater surfaces are properly maintained and kept free of biofouling – i.e. marine life attached to the hull and propeller, which contributes to surface roughness. Thus, with reference to a smooth hull, fuel consumption may practically double when a ship reaches the roughest hour, i.e. when the hull is covered with large shells and marine alga.

The present work investigates ways in which in-water ship hull cleaning by professional divers and remotely-operated devices can be improved, through supporting decisions on when to conduct maintenance, and how strong should cleaning forces be. The ultimate aim is to improve shipping’s energy efficiency and its cost-effectiveness, while reducing chemical and biological impact on the marine environment.

Increased energy efficiency in ships through reduced hull fouling

Swedish Energy Agency, 2015-01-01 -- 2017-06-30.

Completing management options in the Baltic Sea Region to reduce risk of invasive species introduction by shipping COMPLETE

Interreg-BSR, 2017-10-01 -- 2020-09-30.

Subject Categories

Other Engineering and Technologies not elsewhere specified

Environmental Management

Reliability and Maintenance


Chalmers Materials Analysis Laboratory



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4691


Chalmers University of Technology

Saga-building, Hörselgången 4, Chalmers Campus Lindholmen, Gothenburg - SWEDEN

Opponent: Dr. Kelli Zargiel Hunsucker (Ph.D.), Florida Institute of Technology, USA

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