ElectriSea is a Sweden-USA collaboration between Cetasol and Glosten to develop a digital twin tool that integrates real-time operational data with naval architecture. Traditional design-based digital twins struggle in maritime applications because ships are assembled from many independent components and lack unified data models. The approach therefore focuses on data-driven digital twins. By collecting operational data from a vessel, Cetasol’s adaptive models generate customized digital twins that update automatically and can calculate fuel savings, battery sizing and optimal charging locations. The tool is validated against both design calculations and live ferry operations, providing scalable solutions for small and medium-sized vessels and informed investment decisions.