The certificates were issued to those seamen who qualified as masters or mates aboard merchant ships. The documents include certificates of competency, certificates of service, examination applications, and other miscellaneous forms. Collectively, they may include some or all of the following details:
- certificate number
- birth date
- issue port
- issue date
- examination date
- history of service (dates, vessels, occupations, years in service)
UPDATE: There's a video below, giving some further background to the collection.