With the relative wind angle mostly being dead ahead because of the engines, this means that the vessel will effectively be sailing a close hauled course. When sails are trimmed for this heading, most of the force generated by the sail is perpendicular to the direction of the vessel. In normal sailing vessels this perpendicular force is converted into forward velocity with a keel. Without a keel your sailing ship will just drift sideways when attempting to sail a close hauled course. I'm assuming that giant shipping container ships don't have a keel, so how will these sails generate effective forward velocity for the ship and not just drag the ship horizontally off course?