Hull cleaning and propeller polishing
In-water and drydock removal of fouling from hull and propeller, its intervals, its measured efficiency recovery and its regulatory constraints.
Hull cleaning and propeller polishing remove the biofouling that raises frictional resistance and degrades propulsive efficiency between drydockings. The efficiency at stake is substantial and it accumulates continuously, which is why cleaning intervals are an operational decision rather than a docking-cycle one.
The measurable effect appears in the ship’s speed-power relationship rather than in any design index. A cleaned hull and a polished propeller recover part of the added resistance from hull roughness , which shows up in the operational Carbon Intensity Indicator at the next annual submission. It does not move a design benchmark such as the RightShip GHG Rating , which reads design particulars rather than condition.
In-water cleaning is constrained by port and coastal state rules on biofouling discharge and by the risk of coating damage, and capture-and-treat systems are increasingly required. The full article will cover cleaning methods, propeller polishing grades, interval optimisation against fuel price, the evidence a charterer or rating provider will accept, and the regulatory position on in-water cleaning by jurisdiction.