This paper introduces a pioneering 3D scanning approach for preliminary evaluation of Compact Clean type for Ballast Water Treatment System (BWTS) selection, with a focus delivery retrofitting project schedule in shipyard. A comprehensive approach utilizes advanced 3D scanning techniques to capture precise ship geometry and potential location of installation, enabling meticulous assessment of BWTS compatibility within existing structure. Employing 3D models, diverse retrofit scenarios are simulated, offering vital insights for well-informed decision-making. The integrated use of 3D scanning yields substantial advancements in achieving retrofitting objective. This approach demonstrates a high degree of effectiveness in retrofitting, leading to a substantial enhancement in the project schedule, with a remarkable 25% reduction in the time required to complete the retrofitting of the chosen BWTS from the original schedule. It has yielded a commendable 15% reduction in overall costs. Visual representations of retrofit scenarios enhance collaboration among ship owners, BWTS manufacturer, shipyard, supplier and classification society, expediting decision-making and installation procedures. The transformative potential of 3D scanning for BWTS retrofit evaluation is evident in innovative approach were aligned with industry demands for enhanced efficiency and schedule adherence, setting a new benchmark for early project delivery and cost effective BWTS retrofitting. This paper emphasizes the significance of 3D scanning in fostering informed decision-making and operational excellence in retrofitting BWTS on existing ships.