Sustainable Design of an Electrically Actuated Telescopic Gangway for Luxury Yachts

The maritime industry, including the yacht sector, is facing tightening environmental requirements that are reshaping expectations for onboard systems. Although decarbonization initiatives typically prioritize propulsion technologies, auxiliary systems offer a significant and underexploited lever for improvement through electrification, lightweighting, and the removal of hydraulic circuits, with direct benefits in energy use, emissions, and environmental risk. In this context, this thesis addresses the comprehensive redesign of a telescopic gangway manufactured by Amare, with the objective of meeting these evolving requirements while maintaining structural integrity and operational safety. The design challenge centered on achieving a radical reduction in mass while fully eliminating the hydraulic power unit, without compromising the gangway's ability to sustain a 150 kg static load at full extension of 3.3 meters, in compliance with ISO 7061. This required resolving a key limitation observed in prior electrification attempts, namely that electric actuators sized to lift the gangway's dynamic weight often struggle to provide the holding torque required for static passenger loads, typically necessitating complex auxiliary braking solutions. The adopted methodology, based on sustainable product design principles, was structured into five consecutive phases. First, functional decomposition and system analysis identified the hydraulic components and steel structure as the primary optimization targets. Second, a Product Design Specification defined requirements across geometric, kinematic, structural, and environmental dimensions. Third, a morphological analysis compared alternative actuation technologies and structural materials against sustainability criteria. Fourth, embodiment design led to an Aluminum alloy housing box with precision linear guides, a novel 45° wedge luffing mechanism enabling mechanical self-locking, and telescopic sections with optimized cross sectional profiles. Finally, validation through analytical calculations, finite element analysis, and a qualitative life cycle assessment confirmed compliance with performance and sustainability targets. The final design prototype has a total mass of 170 kg, corresponding to a 63% reduction relative to the original gangway. Electromechanical actuation reduces energy consumption by 82% per cycle while eliminating hydraulic oil and the associated aquatic ecotoxicity risk. The life cycle assessment indicates that, despite higher embodied carbon during composite production, the 290 kg mass reduction yields operational fuel savings of 1,230 to 6,960 liters over 15 years, corresponding to 4,300 to 24,600 kg of avoided CO₂ emissions, with a carbon payback within 0.6 to 1.4 years.