(1) Four years total service on ocean or near-coastal waters. Service on Great Lakes and inland waters may substitute for up to 2 years of the required service. Two years of the required service must have been on vessels of more than 100 GRT. Two years of the required service must have been as a master or mate of self-propelled vessels, or master or mate (pilot) of towing vessels, or equivalent position while holding a license or MMC endorsement as master or mate of self-propelled vessels, or master or mate (pilot) of towing vessels. One year of the service as master or mate of self-propelled vessels, or master or mate (pilot) of towing vessels, or equivalent position must have been on vessels of more than 100 GRT; or

(2) One year of service on vessels of more than 100 GRT on ocean or near-coastal waters as a master or mate of self-propelled vessels, or master or mate of towing vessels while holding a license or MMC endorsement as mate of ocean self-propelled vessels of less than 1,600 GRT or as master or mate of towing vessels.