Inland Rules vs COLREGs International — Comparison

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).

Side by side

Feature	Inland Rules (33 CFR Part 83)	COLREGs (International)
Where it applies	Inside the demarcation lines (33 CFR Part 80) — bays, sounds, Great Lakes, Western Rivers	On the high seas and seaward of the demarcation lines
Rule 9 — Narrow Channels	Adds descending-current right-of-way for power-driven vessels on Great Lakes / Western Rivers Read Inland Rule 9	Standard 'keep to your starboard side' with no descending-current exception Read COLREGs Rule 9
Rule 10	Vessel Traffic Services (VTS) — must comply with USCG-regulated VTS Read Inland Rule 10	Traffic Separation Schemes (TSS) — IMO-adopted lanes Read COLREGs Rule 10
Rule 24 — Towing	Special provisions for composite units and Western Rivers towing astern Read Inland Rule 24	Standard tow-light progression by tow length Read COLREGs Rule 24
Rule 28 — Constrained by Draft	Does not exist — Inland numbering jumps from 27 to 29	CBD vessels may show three vertical red all-round lights Read COLREGs Rule 28
Rule 34 — Manoeuvring Signals	Signals of INTENT — 1 short = 'I intend to leave you on my port side'. Vessels must agree before manoeuvring. Read Inland Rule 34	Signals of ACTION — 1 short = 'I am altering course to starboard'. Read COLREGs Rule 34
Exam version	Tested on OUPV Inland and Master Inland	Tested on OUPV Near-Coastal and Master Near-Coastal

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

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 9

COLREGs (International)

Standard 'keep to your starboard side' with no descending-current exception

Read COLREGs Rule 9

Rule 10

Inland Rules (33 CFR Part 83)

Vessel Traffic Services (VTS) — must comply with USCG-regulated VTS

Read Inland Rule 10

COLREGs (International)

Traffic Separation Schemes (TSS) — IMO-adopted lanes

Read COLREGs Rule 10

Rule 24 — Towing

Inland Rules (33 CFR Part 83)

Special provisions for composite units and Western Rivers towing astern

Read Inland Rule 24

COLREGs (International)

Standard tow-light progression by tow length

Read COLREGs Rule 24

Rule 28 — Constrained by Draft

Inland Rules (33 CFR Part 83)

Does not exist — Inland numbering jumps from 27 to 29

COLREGs (International)

CBD vessels may show three vertical red all-round lights

Read COLREGs Rule 28

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 34

COLREGs (International)

Signals of ACTION — 1 short = 'I am altering course to starboard'.

Read COLREGs Rule 34

Exam 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

Which should you pick?

Pick Inland Rules (33 CFR Part 83) if…

Where it applies: Inside the demarcation lines (33 CFR Part 80) — bays, sounds, Great Lakes, Western Rivers
Rule 9 — Narrow Channels: Adds descending-current right-of-way for power-driven vessels on Great Lakes / Western Rivers
Rule 10: Vessel Traffic Services (VTS) — must comply with USCG-regulated VTS
Rule 24 — Towing: Special provisions for composite units and Western Rivers towing astern
Rule 28 — Constrained by Draft: Does not exist — Inland numbering jumps from 27 to 29
Rule 34 — Manoeuvring Signals: Signals of INTENT — 1 short = 'I intend to leave you on my port side'. Vessels must agree before manoeuvring.
Exam version: Tested on OUPV Inland and Master Inland

Pick COLREGs (International) if…

Where it applies: On the high seas and seaward of the demarcation lines
Rule 9 — Narrow Channels: Standard 'keep to your starboard side' with no descending-current exception
Rule 10: Traffic Separation Schemes (TSS) — IMO-adopted lanes
Rule 24 — Towing: Standard tow-light progression by tow length
Rule 28 — Constrained by Draft: CBD vessels may show three vertical red all-round lights
Rule 34 — Manoeuvring Signals: Signals of ACTION — 1 short = 'I am altering course to starboard'.
Exam version: 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.

Last verified: 2026-05-21

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)

Inland Rules vs International COLREGs — Side by Side

Side by side

Where it applies

Rule 9 — Narrow Channels

Rule 10

Rule 24 — Towing

Rule 28 — Constrained by Draft

Rule 34 — Manoeuvring Signals

Exam version

Which should you pick?

Pick Inland Rules (33 CFR Part 83) if…

Pick COLREGs (International) if…

Bottom line

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