The United States is moving into a new era in which the enemy no longer provides symmetric opposition. The Navy and Marine Corps will face new challenges in the way they deploy and conduct future operations. One important way that these challenges will be met involves sea-based operations, which provide the sustainment necessary for prolonged operations and prevent unwanted operational pauses. Recent combat operations in Operation Iraqi Freedom (OIF) demonstrated difficulties when sustaining forces from logistics bases ashore. For example, advancing the Army and Marines to Baghdad in OIF consumed large amounts of fuel and ammunition. The resupply could not replenish supplies and an operational pause began on 29 March, 2003. In order to prevent operational pauses, rapid movement from the sea to the objective must be implemented. This thesis analyzes the problem of finding an optimal mix of Combat Logistics Force shuttle ships required to sustain the sea-base. This is accomplished through two optimization models: The first one determines a shuttle mix ensuring required inventory levels at the sea-base are maintained at all times. Since this requirement may cause some shuttles to be loaded partially, in the second model we manually assign the shuttle mix and then minimize unmet demand. This model yields a mix of shuttles that strikes a balance between shuttle cost and meeting sea-base demand. This thesis uses varying distances for conducting analyses over several scenarios.