Sustainable yacht refits: Structural solutions in methanol-powered conversion

In the pursuit of sustainable solutions to reduce carbon emissions, the maritime industry is increasingly focusing on transitioning from fossil fuels to alternative fuels. Methanol offers significant environmental benefits, including Well-to-Wake greenhouse gas emission reductions of 95% with synthetic methanol and 89% with green methanol. Gray methanol can increase emissions by 20% compared to marine diesel oil. Methanol reduces sulfur oxides by 99%, nitrogen oxides by 60%, and particulate matter by 95%. However, its lower energy density requires 75% larger storage volumes to maintain comparable ranges. This study explores retrofitting a 60-meter yacht for methanol propulsion, addressing structural, spatial, and safety challenges associated with converting existing vessels into more environmentally sustainable ships. Key innovations include compact cofferdams, reduced from 800mm to 100mm, and corrugated bulkheads, improving tank efficiency from 0.32 to 0.83 while preserving safety. A Finite Element Model validated the structural integrity of these solutions, confirming their ability to withstand operational stresses while meeting stringent safety standards. Methanol propulsion provides a 23% range reduction compared to diesel, a trade-off balanced by its environmental advantages. This work highlights the interplay between structural modifications, onboard capacity enhancements, and alternative fuels in maritime decarbonization, contributing to more sustainable and responsible yacht transportation.