Optimization of Maintenance Schedule for Containerships Sailing in the Adriatic Sea

Biofouling attaches to immersed surfaces in between hull cleanings. Due to high speeds and relatively short port times, biofilm often attaches to the immersed surfaces of containerships. In most cases, this type of fouling is not given much importance since it is assumed that it will not cause any fouling penalties. In this paper, the fouling penalties related to fouling with biofilm on the example of the Post Panamax and Post Panamax Plus containership fleets sailing in the Adriatic Sea are assessed. In addition, the investigation is performed for real environmental conditions that a containership can encounter on a sailing route passing through the Adriatic Sea. Thus, the impact of waves and wind is taken into account based on mean values of significant wave height and wind speed for containerships sailing at the design speed along the analyzed route. The procedure for the determination of the detrimental effects of biofilm on the increase in fuel consumption and carbon dioxide emissions is given. Further, the proposed procedure includes the determination of calm water resistance by the Holtrop and Mennen method, the added resistance in waves by Liu and Papanikolaou’s method, spectral analysis using the Tabain’s spectrum for the Adriatic Sea, the wind resistance by the Blendermann method, and added resistance due to biofouling using the Granville method. Thereafter, a time-dependent biofouling growth model proposed by Uzun et al. is incorporated, and the adequate timing for underwater hull cleaning is determined for several hull cleaning costs. The obtained results demonstrate that, from an environmental point of view, proactive hull cleaning should be applied, while, from an economic perspective, optimal timing for underwater hull cleaning is recommended.