The assigning of class to merchant ships according to certain rules established by aclassification society. The classification of the ship helps the owner, in the event of a casualty, to establish that he had used “due diligence” required of him; informs the shipper that he is not taking a disproportionate risk by sending his goods aboard that particular ship; and it helps the underwriters decide about the nature of the risk involved when he is asked to insure the ship.