Master 50 GT — Mid-Tier Captain Credential

Master 50 GT is the mid-tier inspected-vessel master credential — a step above OUPV with the same exam structure as Master 100, but capped at 50 gross tons of inspected-vessel authority.

Last verified: 2026-05-20

Primary sources

46 CFR 11.422 — Tonnage limits for Master or Mate under 200 GRT (eCFR) (retrieved 2026-05-20)
46 CFR 11.428 — Master less than 100 GRT Near Coastal service (eCFR) (retrieved 2026-05-20)
46 CFR 11.455 — Master less than 100 GRT Great Lakes and Inland service (eCFR) (retrieved 2026-05-20)
46 CFR 11.457 — Master less than 100 GRT Inland service (eCFR) (retrieved 2026-05-20)
USCG NMC — Master less than 100 GRT Near Coastal checklist (retrieved 2026-05-20)
USCG NMC — Master less than 100 GRT Great Lakes/Inland checklist (retrieved 2026-05-20)

TL;DR

Master 50 GT uses the same Master less-than-100 framework, but the tonnage calculation lands at 50 GRT instead of 100. The route drives the service baseline: 720 days for Near-Coastal, 360 days for Great Lakes/Inland.

When Master 50 makes sense

If your boat is between 6 passengers (OUPV ceiling) and 50 GT, Master 50 is the right credential. Many charter sport-fish operators in this size run Master 50 because they don't need the additional 50 GT of authority that Master 100 grants.

Sea service and tonnage

For Near-Coastal Master less than 100 GRT, the baseline is 720 days of deck-department service, with up to 360 inland-water days allowed as substitute service. For Great Lakes/Inland, the baseline is 360 total days. The 50 GRT limit comes from the same 46 CFR 11.422 formula: the current NMC Near-Coastal checklist shows 180 days on vessels of 26 GRT or above, or 360 days on vessels of 17 GRT or above; the Great Lakes/Inland checklist shows 90 days on 26+ GRT or 180 days on 17+ GRT.

Path from OUPV

Most candidates earn OUPV first, log enough qualifying service on appropriately sized vessels, then apply to upgrade to Master 50. The Approval to Test letter controls exactly which modules you repeat; many OUPV upgraders focus on the additional Plotting and Master General material rather than retaking every original module.

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