Where it applies
Inland Rules (33 CFR Part 83)
Inside the demarcation lines (33 CFR Part 80) — bays, sounds, Great Lakes, Western Rivers
COLREGs (International)
On the high seas and seaward of the demarcation lines
Inland Rules vs International COLREGs — Side by Side
The US Inland Navigation Rules (33 CFR Part 83) parallel the international COLREGs almost word-for-word. The differences are concentrated in five rules and matter most on the OUPV Near-Coastal exam.
Last verified:
Primary sources
- 33 CFR Part 83 — Inland Navigation Rules (eCFR) (retrieved 2026-05-21)
- 33 CFR §83.09 — Inland Rule 9 Narrow Channels (eCFR) (retrieved 2026-05-21)
- 33 CFR §83.10 — Inland Rule 10 Vessel Traffic Services (eCFR) (retrieved 2026-05-21)
- 33 CFR §83.24 — Inland Rule 24 Towing & Pushing (eCFR) (retrieved 2026-05-21)
- 33 CFR §83.34 — Inland Rule 34 Manoeuvring & Warning Signals (eCFR) (retrieved 2026-05-21)
- 33 CFR Part 80 — COLREGS Demarcation Lines (eCFR) (retrieved 2026-05-21)
- USCG Navigation Center — International Rules of the Road (COLREGs) (retrieved 2026-05-21)
TL;DR
Inland and COLREGs are ~95% identical. The five rules where they meaningfully diverge are 9 (narrow channels), 10 (VTS vs TSS), 24 (towing on Western Rivers), 28 (no Inland constrained-by-draft), and 34 (intent vs action signals).
Rule 9 — Narrow Channels
Inland Rules (33 CFR Part 83)
Adds descending-current right-of-way for power-driven vessels on Great Lakes / Western Rivers
Read Inland Rule 9COLREGs (International)
Standard 'keep to your starboard side' with no descending-current exception
Read COLREGs Rule 9Rule 10
Inland Rules (33 CFR Part 83)
Vessel Traffic Services (VTS) — must comply with USCG-regulated VTS
Read Inland Rule 10Rule 24 — Towing
Inland Rules (33 CFR Part 83)
Special provisions for composite units and Western Rivers towing astern
Read Inland Rule 24Rule 28 — Constrained by Draft
Inland Rules (33 CFR Part 83)
Does not exist — Inland numbering jumps from 27 to 29
Rule 34 — Manoeuvring Signals
Inland Rules (33 CFR Part 83)
Signals of INTENT — 1 short = 'I intend to leave you on my port side'. Vessels must agree before manoeuvring.
Read Inland Rule 34COLREGs (International)
Signals of ACTION — 1 short = 'I am altering course to starboard'.
Read COLREGs Rule 34Exam version
Inland Rules (33 CFR Part 83)
Tested on OUPV Inland and Master Inland
COLREGs (International)
Tested on OUPV Near-Coastal and Master Near-Coastal
Bottom line
If you're studying for OUPV Inland, focus on the Inland Rules and the Western Rivers / Great Lakes deviations. If you're going Near-Coastal, learn both — the demarcation lines mean you'll cross between them on the same trip.