Crude oil washing (COW) is used to remove oil residues from cargo tanks while limiting the production of oily wash water, but its performance depends on equipment integrity and crew readiness. This study examines operational obstacles to COW on MT Swordfish and evaluates the responses taken before the vessel’s scheduled dry docking. A qualitative descriptive case-study approach was applied to observations, interviews with five categories of deck personnel, and shipboard documents collected during November 2023–November 2024. Data were analysed by reducing and comparing evidence across sources. Three equipment-related problems were identified: corrosion-related leakage in starboard COW line No. 4, which interrupted operations for approximately eight hours; malfunctioning fixed tank-washing machines caused by corroded gears; and seized manhole and purging-valve threads that delayed gas-freeing preparations. The reported response involved isolating the affected system, containing the spill, applying a temporary pipe repair, lubricating or manually moving impaired components, and planning permanent replacement during dry docking. Interviews also identified uneven procedural familiarity and workload pressures among the crew. The findings indicate that temporary corrective action enabled operations to continue but did not remove the underlying risks associated with ageing equipment and inconsistent preventive maintenance. A documented inspection programme, prompt replacement of defective components, task-specific training, and strict adherence to inert-gas and hot-work safety controls are recommended