Offshore / Deep-Sea Deck Officer Career Path
Progress from Ordinary Seaman to Master on offshore supply vessels, tankers, and deep-sea ships. Each step requires USCG-issued licenses tied to gross tonnage and route.
Career milestones
- Ordinary Seaman (OS) — The entry point for a professional maritime career. OS work deck maintenance, line handling, and watchstanding under AB supervision. You'll build sea time toward your first rating.
- Able Seaman (AB) — AB is the senior unlicensed deck rating. Qualification requires at least 720 days of sea service plus the AB exam and rating endorsement on your MMC. AB Specials and AB Limiteds have shorter sea-time paths.
- Mate / Third Mate — Your first officer license. Third Mate of Ocean Vessels requires 720–1,080 days of sea service (depending on pathway), STCW officer endorsements, and passing the USCG officer exam. From here the tonnage ladder begins.
- Chief Mate — Chief Mate is the executive officer on deck and the stepping stone to Master. Requires additional sea service at the officer level plus advanced STCW modules (Advanced Fire Fighting, ARPA, etc.).
- Master — The Master holds ultimate authority aboard a vessel. A Master of Ocean Vessels (Unlimited) requires at least 1,080 days of service on ocean-going vessels plus a comprehensive USCG exam. Compensation varies widely by vessel type and operator.