To support the deployment of future offshore facilities aimed at achieving net-zero greenhouse gas emissions by 2050, offshore logistics operators must adjust their fleet management and routing strategies to accommodate diverse facility types. Existing methods for determining optimal vessel fleet size and composition are primarily tailored to offshore wind farm activities, lacking integration across multiple offshore facility types. To address this gap, we propose a Mixed-Integer Linear Programming (MILP) approach to optimize vessel fleet configuration, leveraging traditional solution methods such as branch-and-cut with commercial solvers. This model presents a mixed fleet of crew transfer vessels, service operation vessels, and heavy lift vessels to meet the specific demands of future offshore operations. With a focus on hydrogen power plants and carbon capture and storage platforms in addition to offshore wind farms, it demonstrates how a strategically configured fleet can efficiently support the diverse activities involved in integrating these new facilities.