Many years ago the British Parliament passed a law requiring that a series of marks be painted on the hulls of merchant ships.  They consisted of several lines one above the other. The top one was called the “Plimsoll mark” or “load line.”  It indicated the maximum depth the vessel could be submerged in the water without endangering it in a storm.  The practice of putting these markings on large ships was introduced in Parliament by one of its members, a reformer by the name of Samuel Plimsoll.  Because the legislation he proposed prevented many disasters at sea and saved thousands of lives, he became known as the sailors’ friend.