Estimating Biofouling Performance Penalty of In-Service Ships

The presence of biofouling, or unwanted growth of organisms on ship hulls increases the viscous drag and results in a powering performance penalty. While this performance penalty is known to vary with ship type and speed, most estimates use a constant value to approximate the increase in powering due to biofouling on a ship’s hull. The 2020 International Maritime Organization Greenhouse Gas Study uses a 9% penalty across ships of all sizes and operational profiles. One of the main reasons for using a constant penalty is the lack of sufficient empirical data or an established methodology to accurately estimate the variation in powering due to biofouling across the global fleet. This work aims to provide an initial framework to do such by combining ship hull fouling surveys, Holtrop-Mennen ship power approximation method, power mean approximation for frictional drag of rough surfaces, and notional operational profiles derived from in-service ship data. The results show that the fouling accumulation and therefore drag vary along the length of the ship hull. These findings demonstrate the importance of understanding the variation in biofouling penalties on different parts of the hull and how this impacts the penalties experienced among different ships. This research aims to establish a framework from which to estimate future powering performance penalties.