The most-tested block on the USCG captain's license exam. Learn required lights by vessel type, arc degrees, visibility ranges, day shapes, inland differences, and every exam trap — all in one place.
Navigation lights and day shapes are the primary means by which vessels communicate their identity, status, and intentions to other mariners — especially at night or in reduced visibility. The rules governing lights and shapes are codified in two parallel rule sets that every USCG license candidate must know:
The two sets are nearly identical for lights and shapes, but the exam specifically tests the differences. Both are codified in 33 USC Chapter 34 (Inland) and 33 CFR Part 81 for the COLREGS demarcation lines.
Exam Reality Check
Lights and shapes questions account for roughly 15–20% of the Rules of the Road module on USCG written exams. For an OUPV (6-pack) exam with 12 Rules of the Road questions, expect 2–4 directly on lights and shapes. For a Master 100-ton exam, the number is higher. Memorize the arc degrees, ranges, and vessel-type requirements cold.
Rule 20 establishes the fundamental duty to display lights. The rule is simple but the exam tests its precise language:
“These Rules shall be complied with in all weathers. The Rules concerning lights shall be complied with from sunset to sunrise, and during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper look-out. The lights prescribed by these Rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility and may be exhibited in all other circumstances when it is deemed necessary.”
Mandatory display period
Sunset to sunrise — always required during these hours regardless of visibility conditions.
Restricted visibility
Lights must also be shown during restricted visibility in daylight hours. Lights may be shown at any other time when deemed necessary.
Day shapes
Shapes apply from sunrise to sunset. A vessel required to show a shape by day shows corresponding lights at night.
No confusing lights
No lights that could be mistaken for required navigation lights may be shown during the hours of darkness.
Rule 21 defines each light type by its color and arc. These definitions are universal — the same arcs apply regardless of vessel type. Memorize the five arcs as exact degree values; the exam will test them directly.
| Light | Color | Arc | Direction |
|---|---|---|---|
| Masthead (Steaming) | White | 225° | Forward — from dead ahead to 22.5° abaft the beam on each side |
| Sidelight (Port) | Red | 112.5° | Port side — from dead ahead to 22.5° abaft the beam (port side) |
| Sidelight (Starboard) | Green | 112.5° | Starboard side — from dead ahead to 22.5° abaft the beam (starboard side) |
| Sternlight | White | 135° | Aft — from dead astern to 67.5° on each side |
| All-Round Light | Various | 360° | Visible from any direction; color varies by context (white, red, green, yellow) |
| Towing Light | Yellow | 135° | Same arc as sternlight; shown above the sternlight on towing vessels (Inland) |
Arc Memory Trick
The masthead (225°) plus the sternlight (135°) = 360°. Together they cover the entire horizon. The two sidelights each cover 112.5°, which is exactly half of the masthead arc. The masthead and the two sidelights together cover 225° + 112.5° + 112.5° = 450° — meaning there is significant overlap between the masthead and sidelights ahead of the vessel. The sidelights cut off at 22.5° abaft the beam, the same point where the masthead light cuts off.
Rule 22 specifies the minimum visibility range (in nautical miles) for each light, based on vessel length. These are minimum standards — lights may be brighter but not dimmer.
| Light Type | 50 m or more | 12–50 m | Under 12 m | Under 7 m (<7 kn) |
|---|---|---|---|---|
| Masthead light | 6 nm | 5 nm | 2 nm | — |
| Sidelights | 3 nm | 2 nm | 1 nm | 1 nm |
| Sternlight | 3 nm | 2 nm | 2 nm | 2 nm |
| Towing light (yellow) | 3 nm | 2 nm | 2 nm | — |
| All-round white / all-round lights | 3 nm | 2 nm | 2 nm | 2 nm |
Note: For vessels under 7 m with a maximum speed of 7 knots, sidelights and all-round lights must be visible at 1 nm minimum.
The following rules each cover a specific vessel category. Understanding which rule governs which vessel is itself tested on the exam.
Rule 23 is the baseline for the most common vessel type. The lights required depend on vessel length:
| Vessel Length | Required Lights |
|---|---|
| 50 m or more | Forward masthead light; aft masthead light (higher and farther aft); sidelights; sternlight |
| Under 50 m | Masthead light; sidelights; sternlight (second masthead optional) |
| Under 12 m | Option: all-round white light plus sidelights (instead of masthead + sternlight) |
| Under 7 m, max 7 kn | Option: all-round white light only (sidelights if practicable) |
Height Rule for Two Masthead Lights
On vessels 50 m or more: the forward masthead light must be at least 6 m above the hull. The after masthead light must be at least 4.5 m higher than the forward masthead light. This creates a visible “slope” that indicates direction of travel — the higher light is always aft.
Rule 24 covers vessels engaged in towing or pushing another vessel or object. The configuration of towing lights signals both that a vessel is towing and whether the tow is long or short.
| Situation | Towing Vessel Lights | Towed Vessel / Object Lights |
|---|---|---|
| Tow length 200 m or less | 2 masthead lights vertically; sidelights; sternlight; yellow towing light above sternlight (Inland only) | Sidelights and sternlight |
| Tow length over 200 m | 3 masthead lights vertically; sidelights; sternlight; yellow towing light (Inland) | Sidelights and sternlight; diamond shape by day |
| Pushing ahead (rigid composite) | 2 masthead lights forward; sidelights; sternlight | Lights on front of pushed vessel: sidelights at bow; no separate sternlight required |
| Pushing ahead (not rigid composite) | 2 masthead lights forward; sidelights; sternlight | Sidelights at bow of pushed vessel; sternlight on pushing vessel |
Tow Length: How It's Measured
The 200 m threshold is measured from the stern of the towing vessel to the stern of the last towed object. It includes the length of the tow line, the length of intermediate towed vessels, and the length of the last towed object. This is a common exam question phrased as “what determines whether two or three masthead lights are required?”
A sailing vessel under sail alone is NOT a power-driven vessel — it does not show a masthead (steaming) light. This is the single most important distinction in Rule 25.
| Vessel Type | Required Lights | Options |
|---|---|---|
| Sailing vessel any size | Sidelights + sternlight | Optional red-over-green all-round lights at masthead |
| Sailing vessel under 20 m | Sidelights + sternlight | May combine into tricolor lantern at masthead (in lieu of separate sidelights + sternlight) |
| Sailing vessel under 7 m | Sidelights + sternlight if practicable | If impracticable: all-round white light, ready to show to prevent collision |
| Sailing vessel using engine | All lights for power-driven vessel (Rule 23) | Day: cone apex-downward forward to indicate propulsion by engine |
| Vessel under oars | Sidelights + sternlight if practicable | If impracticable: all-round white light, ready to show to prevent collision |
Tricolor Restriction
A vessel using the tricolor masthead lantern (combining sidelights and sternlight) may NOT simultaneously show the optional red-over-green identification lights. The two systems are mutually exclusive.
Rule 26 distinguishes between trawling and non-trawling fishing. The difference matters because trawl gear severely restricts maneuverability — hence the different light pattern signaling other vessels to keep clear.
| Vessel Type | All-Round Lights (vertical) | Additional Lights | Day Shape |
|---|---|---|---|
| Trawling (any size) | Green over white | Sidelights + sternlight if making way; optional masthead light if over 50 m | Two cones apex-to-apex (bicone) |
| Fishing (not trawling) | Red over white | Sidelights + sternlight if making way; outward light toward gear | Cone apex-downward; ball toward gear if gear extends more than 150 m |
Memory Aid: Trawling vs. Fishing
Rule 27 covers two high-priority vessel categories that other vessels must keep clear of. Understanding the difference between NUC and RAM, and the specific lights for each, is critical for the exam.
| Category | Definition | Night Lights | Day Shapes |
|---|---|---|---|
| NUC | Unable to maneuver due to exceptional circumstances; cannot comply with Rules | 2 all-round red lights vertically; sidelights + sternlight if making way | 2 black balls vertically |
| RAM | Nature of work restricts ability to maneuver; must deviate from Rules | All-round red-white-red vertically; sidelights + sternlight if making way; anchor lights if anchored | Ball-diamond-ball vertically |
| RAM — Dredge | Dredging or underwater operations with obstruction | RAM lights + 2 red all-round vertically on obstruction side + 2 green all-round vertically on clear side | RAM shapes + 2 balls on obstruction side + 2 diamonds on clear side |
| RAM — Mine Clearance | Engaged in mine clearance operations | 3 all-round green lights: one at masthead, one at each yardarm | 3 black balls in same positions; danger zone 1000 m ahead, 500 m on each side |
NUC Examples
RAM Examples
A vessel constrained by draft is a power-driven vessel that, because of its draft relative to available depth and width of navigable water, cannot deviate from its course. CBD status is unique to COLREGS — Inland Rules have no equivalent.
Night — Lights
All lights of a power-driven vessel underway (Rule 23) PLUS 3 all-round red lights in a vertical line
Day — Shape
A cylinder (black) displayed where it can best be seen
CBD vs. RAM vs. NUC — Exam Trap
CBD applies only to power-driven vessels under COLREGS — not under Inland Rules. A CBD vessel CAN maneuver, but only within severe constraints. A RAM vessel's work prevents deviation. A NUC vessel physically cannot maneuver at all. The exam tests whether you know that “constrained by draft” is a COLREGS-only category.
Rule 30 specifies lights for stationary vessels. The length thresholds are 50 m and 100 m. Anchored vessels and grounded vessels are distinguished by additional lights/shapes.
| Vessel | Night — Lights | Day — Shape |
|---|---|---|
| At anchor, under 50 m | 1 all-round white light forward (where best seen) | 1 black ball forward |
| At anchor, 50 m or more | All-round white forward + all-round white aft (aft light lower); deck illumination (may) | 1 black ball forward |
| At anchor, 100 m or more | Same as above + must illuminate deck and working areas | 1 black ball forward |
| Aground, under 50 m | Anchor lights + 2 all-round red lights vertically | 3 black balls vertically (anchor ball + 2 additional) |
| Aground, 50 m or more | Two anchor lights + 2 all-round red lights vertically | 3 black balls vertically |
Anchor Light Exceptions
Vessels under 7 m are not required to show anchor lights or shapes unless anchored in or near a narrow channel, fairway, anchorage, or where other vessels normally navigate. Vessels under 12 m when anchored in a special anchorage area designated by the Secretary are also exempt.
Pilot vessels on duty show a distinctive white-over-red all-round light combination at the masthead, visible from all directions, plus standard underway lights when underway.
On pilotage duty — underway
All-round white over all-round red at masthead; sidelights; sternlight
On pilotage duty — at anchor
All-round white over all-round red at masthead; anchor lights
Day shapes are the daytime equivalent of navigation lights. They are displayed from sunrise to sunset and must be positioned where they can best be seen. All standard shapes are black. The exam tests shape identification and the correct number of shapes for specific vessel situations.
| Shape | Description | Vessel / Situation | Quantity |
|---|---|---|---|
| Ball | Black sphere | At anchor (Rule 30) | 1 forward |
| Balls (2) | Two black spheres, vertical | NUC (Rule 27) | 2 vertical |
| Balls (3) | Three black spheres, vertical | Aground (Rule 30) | 3 vertical |
| Diamond | Black rhombus (square on corner) | Tow over 200 m (on towed vessel, Rule 24) | 1 |
| Ball-Diamond-Ball | Ball, diamond, ball — vertical | RAM (Rule 27) | 3 vertical |
| Cylinder | Black cylinder | Constrained by draft / CBD (Rule 28, COLREGS only) | 1 |
| Cone (apex down) | Black cone, apex pointing down | Fishing (not trawling, Rule 26); also sailing vessel using engine (Rule 25) | 1 |
| Bicone | Two cones, apex-to-apex | Trawling vessel (Rule 26) | 1 bicone |
| Basket | Black basket | Fishing vessel (optional, traditional, mostly Inland) — no COLREGS equivalent | 1 |
Shape Quick-Reference Card
The exam tests Inland vs. COLREGS differences directly. The differences are few but specifically targeted. Know each one cold.
| Topic | COLREGS (International) | Inland Rules |
|---|---|---|
| Towing vessel — sternlight | White sternlight only | Yellow towing light shown ABOVE the white sternlight |
| Constrained by Draft (CBD) | Rule 28: 3 all-round red lights; cylinder by day | No equivalent — CBD does not exist under Inland Rules |
| Small vessel on Western Rivers (<65 ft) | Standard Rule 23 lights | Single all-round white light (when <65 ft on Western Rivers; lights on sides of vessel optional) |
| Passing lights — inland vessels | Not used | Vessels may carry optional all-round white “passing light” on Western Rivers (in lieu of sternlight; shows aft and to the side for passing situations) |
| Anchor lights in special anchorage | Not specifically exempted by anchorage type | Vessels under 20 m in special anchorage area designated by Secretary need not show anchor lights/shapes |
| Vessel being pushed ahead, not composite | Sidelights at forward end; sternlight on pushing vessel | Same requirements; additionally the pushing vessel shows forward masthead lights equal to number required by tow length |
Yellow Towing Light: The #1 COLREGS vs. Inland Exam Question
The yellow towing light is the most frequently tested Inland vs. COLREGS difference. Under Inland Rules, a power-driven vessel towing astern shows a yellow towing light in the same arc as the sternlight (135°), positioned above the white sternlight. Under COLREGS, no yellow towing light is required — just the white sternlight. If an exam question asks “what additional light does a towing vessel show under Inland Rules,” the answer is the yellow towing light.
A seaplane on the water must show lights as closely matching the required lights for an equivalent power-driven vessel as practicable. WIG craft operating in displacement mode comply with Rule 23 for power-driven vessels. WIG craft in ground-effect mode show a flashing all-round red light in addition to standard underway lights — this is the only flashing light required by the Rules.
A vessel with divers below is classified as RAM (Rule 27). It shows all-round red-white-red vertically. If too small to show full RAM lights, it shows a rigid replica of the International Code flag “A” (blue-white swallowtail) at least 1 m in height, visible from all directions, as the dive flag.
Law enforcement vessels may show an alternating blue flashing light (in US waters) to identify themselves. This does not replace required navigation lights — it is in addition to them. The Rules do not require blue lights; they are authorized by national authority, not COLREGS.
For vessels 50 m or more anchored: the forward all-round white light must be higher than the after all-round white light. This mirrors the masthead light configuration for underway power-driven vessels, allowing observers to tell whether the vessel is anchored (equal-intensity but different-height whites) vs. moving (forward lower, after higher for steaming lights).
These are the specific mistakes that most commonly cost exam candidates points. Each trap represents a nuance that the exam deliberately tests.
Trap 1: Sailing Vessel + Engine = Power-Driven Vessel
A sailing vessel using its engine — even if sails are also up — is treated as a power-driven vessel under Rule 23. It must show a masthead (steaming) light. By day it must display a cone, apex down, forward. Many candidates incorrectly answer that a motorsailer shows only sailing vessel lights.
Trap 2: CBD is COLREGS Only
Constrained by Draft (CBD) does not exist under Inland Rules. If an exam question asks about CBD under Inland Rules, the answer is that Inland Rules have no such category. The three all-round red lights and cylinder shape are exclusively COLREGS.
Trap 3: NUC Does NOT Show a Masthead Light
A NUC vessel shows only the two all-round red lights (plus sidelights and sternlight if making way). It does NOT show a masthead (steaming) light. The same applies to RAM vessels — no masthead light. Only power-driven vessels underway per Rule 23 show the masthead light.
Trap 4: Fishing vs. Trawling Light Colors
Trawling = green over white. Fishing (not trawling) = red over white. Swapping these two is the most common mistake on Rule 26 questions. Remember: green for trawl (active, dragging net), red for fixed gear (stopped, passive).
Trap 5: Masthead Arc Is 225°, NOT 360°
The masthead light covers only 225° — it does not cover the area abaft the beam. When questions ask what you can see from directly astern of a power-driven vessel, the answer includes the sternlight and possibly sidelights at the extreme edge, but NOT the masthead light.
Trap 6: Sternlight Is 135°, Not 180°
The sternlight covers 135° aft, extending 67.5° on each side. The question “from what angle can you see both a sidelight and the sternlight?” The overlap zone begins at the sidelight cutoff (22.5° abaft the beam) and extends to 67.5° abaft the beam. From 67.5° to 112.5° abaft the beam, you can see only the sidelight. From 67.5° abaft the beam aft, you see only the sternlight.
Trap 7: Three Masthead Lights Mean Tow Over 200 m
Two masthead lights = towing, tow length 200 m or less. Three masthead lights = towing, tow length exceeds 200 m. The number of masthead lights is what signals tow length to approaching vessels. This is specifically tested with the question: “A towing vessel shows three masthead lights — what does this tell you?”
Trap 8: Anchor Light Exemptions Have Conditions
Vessels under 7 m are exempt from anchor lights only when NOT anchored in or near a channel, fairway, or area where vessels navigate. If a small vessel anchors in a channel, it must show an anchor light even if under 7 m. The exam presents scenarios with anchoring locations to test whether the exemption applies.
Trap 9: Vessel Aground = Anchor Lights PLUS Two Red Lights
A vessel aground shows anchor lights (1 or 2 all-round white depending on length) plus two all-round red lights in a vertical line. The day shape is three balls in a vertical line. This is an additive signal — aground = anchor + extra red. Forgetting the anchor lights is the common exam error.
Trap 10: Red-Over-Green on Sailing Vessel Is Optional
The red-over-green all-round lights at the masthead of a sailing vessel (indicating “I am under sail”) are optional — not required. And when a vessel uses the tricolor lantern option (under 20 m), it cannot simultaneously show the red-over-green. They are mutually exclusive options.
| Rule | Topic | Key Points |
|---|---|---|
| 20 | Application | Sunset to sunrise required; restricted visibility by day; all weathers |
| 21 | Definitions | Masthead 225°, sidelights 112.5°, sternlight 135°, all-round 360°, towing light 135° |
| 22 | Visibility of lights | Ranges by vessel length: 50 m+ (6/3/3 nm); 12–50 m (5/2/2 nm); under 12 m (2/1/2 nm) |
| 23 | Power-driven vessels underway | Masthead + sidelights + sternlight; 2nd masthead if 50 m+; all-round white option under 12 m |
| 24 | Towing and pushing | 2 masthead (tow <200 m); 3 masthead (tow >200 m); yellow towing light (Inland only) |
| 25 | Sailing vessels and vessels under oars | No masthead light; sidelights + sternlight; tricolor option under 20 m; cone apex-down if using engine |
| 26 | Fishing vessels | Trawling: green/white; not trawling: red/white; shapes: bicone (trawling), cone apex-down (not trawling) |
| 27 | NUC and RAM vessels | NUC: red/red; RAM: red/white/red; dredge: + obstruction/clear side lights |
| 28 | Constrained by draft (COLREGS only) | Rule 23 lights + 3 all-round red; cylinder by day; no Inland equivalent |
| 29 | Pilot vessels | All-round white over all-round red at masthead; standard underway/anchor lights otherwise |
| 30 | Anchored and aground | Anchor: 1 or 2 all-round white; Aground: anchor lights + 2 all-round red; shapes: 1 ball / 3 balls |
| 31 | Seaplanes and WIG | Closest practicable compliance to equivalent vessel lights; WIG in ground-effect adds flashing all-round red |
Work through these to test your retention before reviewing the answers. These are representative of actual USCG exam question formats.
Q1. A vessel displays two masthead lights forward, sidelights, and a sternlight. No yellow light is visible. Which is most likely true?
A. Towing vessel under Inland Rules, tow under 200 m
B. Towing vessel under COLREGS, tow under 200 m
C. Pushing vessel (rigid composite) under Inland Rules
D. Power-driven vessel over 50 m
Answer: B
Under COLREGS, a vessel towing shows 2 masthead lights (tow 200 m or less) with no yellow towing light — the yellow towing light is an Inland Rules requirement only. Under Inland Rules the same configuration would include the yellow light above the sternlight. A rigid composite pushing unit shows 2 masthead lights FORWARD (not the standard forward position). A vessel over 50 m shows forward and aft masthead lights (fore-and-aft, not both forward).
Q2. By day, a vessel displays ball-diamond-ball in a vertical line. What is her status?
A. Not Under Command
B. Constrained by Draft
C. Restricted in Ability to Maneuver
D. Vessel at anchor with tow
Answer: C
Ball-diamond-ball is the day shape for RAM (Restricted in Ability to Maneuver), Rule 27. NUC shows 2 balls. CBD shows a cylinder. An anchored vessel shows 1 ball.
Q3. What is the arc of visibility for a sternlight?
A. 112.5 degrees
B. 135 degrees
C. 180 degrees
D. 225 degrees
Answer: B — 135 degrees
The sternlight covers 135° from dead astern, extending 67.5° to each side. This is the same arc as the yellow towing light. 112.5° is each sidelight. 225° is the masthead light. 180° is a common wrong answer.
Q4. A sailing vessel under 20 m is using its diesel engine in calm conditions but has all sails set. What lights does she show at night?
A. Sidelights and sternlight only — same as a pure sailing vessel
B. Tricolor lantern at masthead
C. Masthead light, sidelights, and sternlight — same as a power-driven vessel
D. Red-over-green masthead lights plus sidelights
Answer: C
Whenever a vessel is using its propulsion machinery — regardless of whether sails are also set — it is classified as a power-driven vessel per Rule 3 and must show the lights required by Rule 23. The tricolor is only for sailing vessels under sail alone. No masthead light may be shown when sailing.
Q5. Under Inland Rules, what additional light does a power-driven vessel engaged in towing astern show that is NOT required under COLREGS?
A. A second masthead light forward
B. An all-round yellow light at the masthead
C. A yellow towing light in the same arc as the sternlight, above the sternlight
D. Three masthead lights vertically
Answer: C
Inland Rules require a yellow towing light (135° arc, same as sternlight) positioned above the white sternlight. This is the primary difference between Inland and COLREGS for towing lights. Under COLREGS, only the white sternlight is shown aft.
Masthead (steaming) light: white, 225 degrees forward. Port sidelight: red, 112.5 degrees. Starboard sidelight: green, 112.5 degrees. Sternlight: white, 135 degrees aft. All-round light: any color as required, 360 degrees. The masthead arc plus the sternlight arc equals exactly 360 degrees, covering the entire horizon together.
A power-driven vessel underway shows a masthead (steaming) light forward, sidelights (red port, green starboard), and a sternlight (white, 135 degrees). Vessels 50 m or more in length must also show a second masthead light aft and higher. Vessels under 12 m may substitute an all-round white light plus sidelights in place of the masthead and sternlight combination. Vessels under 7 m with a maximum speed of 7 knots may show only an all-round white light.
A sailing vessel underway under sail alone shows sidelights and a sternlight — but NO masthead steaming light. Vessels under 20 m may combine these into a single tricolor lantern at the masthead. Optionally, a sailing vessel may show a red-over-green all-round light at the masthead to signal sailing status. Vessels under 7 m may show only a white all-round light if the required lights are impracticable.
A vessel at anchor displays one black ball forward. A vessel aground displays three black balls in a vertical line. The three-ball configuration represents the one anchor ball plus two additional balls indicating the aground condition. At night, an anchored vessel shows anchor light(s); a vessel aground shows anchor lights plus two all-round red lights vertically.
The primary differences: Inland Rules require a yellow towing light (135 degree arc) above the white sternlight on towing vessels — COLREGS do not. Constrained by Draft (CBD) exists only under COLREGS (Rule 28) and has no Inland equivalent. Inland Rules allow certain small vessels on Western Rivers to show a single all-round white light. Inland Rules also permit vessels under 20 m anchored in designated special anchorage areas to omit anchor lights and shapes.
A Not Under Command vessel shows two all-round red lights in a vertical line. When making way it also shows sidelights and a sternlight. It does NOT show a masthead (steaming) light. By day it shows two black balls in a vertical line. NUC applies when a vessel is unable to maneuver due to exceptional circumstances such as engine failure or steering casualty.
A RAM vessel displays ball-diamond-ball in a vertical line during daylight. At night it shows all-round red-white-red lights vertically. When making way it adds sidelights and sternlight. When at anchor it adds anchor lights. RAM examples include dredges, cable-layers, replenishment ships, survey vessels, and vessels with divers below.
Ranges are set by vessel length under Rule 22. For vessels 50 m or more: masthead lights 6 nm, sidelights 3 nm, sternlight 3 nm, all-round lights 3 nm. For vessels 12 to 50 m: masthead 5 nm, sidelights 2 nm, sternlight 2 nm. For vessels under 12 m: masthead or all-round white 2 nm, sidelights 1 nm, sternlight 2 nm. These are minimums — actual lights may be brighter.
ColRegs Lights & Shapes — OUPV Guide
OUPV-focused breakdown of ColRegs Part C including arc definitions and vessel-type requirements.
ColRegs Full Study Guide
Complete ColRegs overview from Part A definitions through Part F verification, including steering and sailing rules.
Inland Rules Deep Dive
Complete coverage of US Inland Rules including differences from COLREGS on lights, sound signals, and right of way.
Sound Signals — Rules 32–37
All maneuvering and warning sound signals, fog signals by vessel type, and equipment requirements.
Right of Way and Steering Rules
Give-way and stand-on vessel responsibilities, crossing, head-on, and overtaking situations.
Advanced ColRegs Topics
Restricted visibility rules, traffic separation schemes, and complex vessel encounter scenarios.
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