Sonic Contrasts at Sea: A Comparative Case Study of Noise Exposure and Crew Fatigue on a Conventional Ferry and a High-Speed Craft

Abstract

This study provides a comparative analysis of noise exposure and its occupational implications for two types of vessels operating in the Strait of Gibraltar: a conventional steel roll-on/roll-off passenger ferry (Ro-Pax) and an aluminium high-speed catamaran (HSC). A mixed-methods approach was employed, integrating objective acoustic measurements with subjective assessments of fatigue, workload, and circadian typology using validated survey instruments. The comparative framework is based on International Maritime Organization (IMO) Resolution A.468(XII), which establishes design-based noise limits for both vessel types. This framework is supported by the High-Speed Craft (HSC) Code and European Union (EU) Directive 2003/10/EC, both of which address occupational exposure. While both vessels comply with IMO design standards, the HSC consistently exceeds the noise limits set out in the HSC Code and European regulations in the accommodation and bridge areas. These elevated noise levels correlate with higher fatigue and workload scores among HSC crew, particularly in the engine and deck departments. In contrast, the Ro-Pax ferry demonstrates better acoustic insulation due to its steel construction, resulting in lower overall exposure and improved rest conditions. The results highlight the inadequacy of applying uniform noise standards to structurally distinct vessels, emphasising the importance of vessel-specific acoustic management strategies. Crucially, the study reaffirms the importance of maintaining compliance with both IMO design standards and EU occupational health regulations to ensure the comprehensive protection of seafarers’ well-being and safety.