Six classes of licenses shall be granted:
(1) First class, to persons capable of piloting ships or vessels of any practical draft of water;
(2) Second class, to persons capable of piloting ships or vessels drawing 45 feet of water or under;
(3) Third class, to persons capable of piloting ships or vessels drawing 40 feet of water or under;
(4) Fourth class, to persons capable of piloting ships or vessels drawing 35 feet of water or under;
(5) Fifth class, to persons capable of piloting ships or vessels drawing 32 feet of water or under; and
(6) Sixth class, to persons capable of piloting ships or vessels drawing 27 feet of water or under.