3rd (Third) Mate. 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 are recency- 90 days in the past 3 years on vessels of appropriate tonnage, 1080 days of deck service on Ocean/NC steam or motor vessels, of which 180 days as AB, Boatswain, or Quartermaster, (while holding AB) 90 days of engine department service may be creditable, or graduation from a maritime academy. Other requirements include completing a First Aid course, CPR course, approved firefighting courses, and a valid, approved radar observer course. All candidates must complete an examination.