(1) One year of service as a mate or first-class pilot while acting in the capacity of first mate of Great Lakes self-propelled vessels of 1,600 GRT or more while holding a license or MMC endorsement as mate inland or first-class pilot of Great Lakes and inland self-propelled vessels of unlimited tonnage;

(2) Two years of service as master of self-propelled vessels of 1,600 GRT or more on inland waters, excluding the Great Lakes; or

(3) One year of service upon Great Lakes waters while holding a license or MMC endorsement as mate or first-class pilot of Great Lakes and inland self-propelled vessels of 1,600 GRT or more. A minimum of 6 months of this service must have been in the capacity of first mate. Service as second mate is accepted for the remainder on a two-for-one basis to a maximum of 6 months (2 days of service equals 1 day of creditable service).