Inland Rules vs COLREGs International — Comparison

The short answer

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.

Frequently asked

What's the difference between Inland Rules (33 CFR Part 83) and COLREGs (International)?

Which should you choose: Inland Rules (33 CFR Part 83) or COLREGs (International)?

Last verified: 21 May 2026

Primary sources

33 CFR Part 83 — Inland Navigation Rules (eCFR) (retrieved 21 May 2026)
33 CFR §83.09 — Inland Rule 9 Narrow Channels (eCFR) (retrieved 21 May 2026)
33 CFR §83.10 — Inland Rule 10 Vessel Traffic Services (eCFR) (retrieved 21 May 2026)
33 CFR §83.24 — Inland Rule 24 Towing & Pushing (eCFR) (retrieved 21 May 2026)
33 CFR §83.34 — Inland Rule 34 Manoeuvring & Warning Signals (eCFR) (retrieved 21 May 2026)
33 CFR Part 80 — COLREGS Demarcation Lines (eCFR) (retrieved 21 May 2026)
USCG Navigation Center — International Rules of the Road (COLREGs) (retrieved 21 May 2026)

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

Frequently asked

What's the difference between Inland Rules (33 CFR Part 83) and COLREGs (International)?

Which should you choose: Inland Rules (33 CFR Part 83) or COLREGs (International)?

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