Mate of Unlimited GRT upon Great Lakes and Inland Waters. This is an advanced-level merchant mariner credential. The general requirements for this credential are TWIC Card (Identification, Fingerprints, Citizenship, Social Security number, etc), CG-719B Application, NDR Consent & Check, Oath, 3 letters of recommendation, photograph (supplied by TSA), SSEB Screening complete, age of 21 or over, CG-719K Physical Exam, Medical Tab in MMLD, Drug Testing Compliance, Mariner Fees, and Sea Service Letters or Discharges. Sea service requirements include recency- 90 days in the past 3 years on vessels, 1080 days of deck service on steam or motor vessels, of which 90 days of service on vessels on Inland waters, and 180 days of service as AB, INL Mate, Boatswain, Wheelsman, Quartermaster of equivalent position; or graduation from the deck class of the Great Lakes Maritime Academy; or 360 days of service as master on vessels over 200 GRT while holding an Officer rating as Master 1600 GRT GL & INL. There are also tonnage requirements. Other requirements include a First Aid course, CPR course, approved firefighting courses (Basic & Advanced). All candidates must complete an examination.