Rules of the Road Quiz

'Red Right Returning' is the US rule in IALA Region B — keep red buoys on your starboard (right) side when returning from sea. This is opposite to IALA Region A (Europe) where red is kept to port on return.

The buoyage system defines the physical channel; Rule 9 governs vessel behavior within it. Vessels must keep to starboard in narrow channels, and vessels that can only navigate safely in the channel have right-of-way protection under Rule 9.

'Fl R 6s' means a red (R) flashing (Fl) light with a period of 6 seconds — one flash every 6 seconds. Flashing means the period of darkness is longer than the flash. You can time it: one flash every 6 seconds.

Mid-channel fairway buoys use white light with Morse code A (Mo(A)) — a dot followed by a dash. This characteristic is internationally standardized for safe-water marks, which can be passed on either side.

Nominal range is the distance at which a light is visible in clear weather (meteorological visibility of 10 nautical miles). It is a function of the light's intensity, not its height. In reduced visibility, the effective range is less.

Multiple lights can share the same characteristic, which is why the Light List includes positions and ranges. By knowing the expected range and sequence of lights on your route, you identify each light as you approach it, in the order you expect to see it.

The height in a Light List entry is the elevation of the light above mean high water — this determines geographic range (how far away you can see it due to the curvature of the earth at your eye height above water).

In the US (IALA Region B): 'Red Right Returning' means red buoys are kept to starboard when returning from sea. Green buoys are kept to port when returning (and therefore to starboard when entering). A green buoy to your port means you are entering from sea.

'Fl(3) G 9s' means a group flashing light: 3 green flashes in a group, followed by darkness, with the complete cycle repeating every 9 seconds. Count the flashes in a group and time the period to confirm the light's identity.

Charts show the characteristic and approximate position of a light. The Light List adds the exact geographic coordinates, nominal range in nautical miles, the height above MHW, the structure description, any sector information, and operational remarks.

There are a limited number of practical light characteristics, so repetition along a long coastline is normal. You identify each light by its expected position along your route and the order in which you encounter it, as well as its range — the Light List provides all of this detail.

Safe-water (fairway/mid-channel) marks use Mo(A) — white light showing Morse code letter A (dot-dash). They can be passed on either side and mark the center of a navigable channel or fairway entrance.

Under the Pennsylvania Rule, a vessel violating a navigation statute at the time of a collision has the burden of proving that the violation could not have contributed to the accident. This is a heavy burden — courts presume the violation was causally related to the collision unless proven otherwise.

The stand-on vessel's obligation is to maintain course and speed — but only until inaction becomes unreasonable. Rule 17 requires the stand-on vessel to eventually take action when it is clear the give-way vessel is not complying. Maintaining course into an avoidable collision can constitute contributory negligence.

Property damage of $2,000 or more triggers the reporting requirement, and the report must be filed within 10 days of the accident. The 48-hour deadline applies only to incidents involving death or disappearance.

USCG Form CG-3865 is the Boating Accident Report used for recreational vessel accidents. It is typically filed with the state boating authority (not directly with the USCG) in the state where the accident occurred.

The federal BUI BAC limit is 0.08%, the same as the standard driving limit in all U.S. states. States may impose lower limits or additional restrictions. The USCG and state marine patrol agencies actively enforce BUI laws, and a conviction carries significant penalties.

Many marine insurance policies include provisions that reduce or deny coverage when the insured vessel was in violation of navigation rules at the time of the incident. COLREGS compliance protects not only third-party liability but also your own insurance recovery.

Under the Pennsylvania Rule, a vessel in violation of a navigation statute at the time of a collision must prove that the violation could not have contributed to the accident. This is a very difficult standard — courts presume a causal link between the violation and the collision.

An injury requiring medical treatment beyond first aid triggers the 10-day reporting deadline. The 48-hour deadline applies to accidents involving death or disappearance. The report is filed using Form CG-3865 with the state boating authority.

Under 33 U.S.C. § 2233, the operator must stop and render assistance 'to the extent possible without serious danger to the vessel or persons aboard.' Fault is irrelevant to this duty — even if the other vessel caused the collision, the duty to render assistance applies unless doing so would create serious danger.

The federal threshold for reporting property damage is $2,000. If the combined damage to the vessel and other property totals $2,000 or more, or if the vessel is destroyed, a boating accident report must be filed within 10 days.

The USCG has statutory authority to board any U.S.-flagged vessel or any vessel in U.S. waters and conduct a safety inspection at any time without a warrant. This authority extends to checking safety equipment, documentation, and compliance with navigation rules.

The COLREGS Demarcation Line is defined in 33 CFR Part 80 and is marked on NOAA nautical charts as a dashed magenta line. Its location varies by port — you must identify it on the chart for each harbor you use.

The Chesapeake Bay is classified as an inland waterway, so U.S. Inland Navigation Rules apply throughout the Bay. International COLREGS apply only after crossing the COLREGS Demarcation Line at the Bay entrance and proceeding into the Atlantic.

Vessel Constrained by Draft (CBD) is recognized only in International COLREGS. The Inland Rules do not include this category. A vessel displaying three red lights vertically is a CBD vessel operating under International Rules — there is no Inland Rules equivalent.

The Inland Rules include a provision for U.S. law enforcement vessels to display a flashing blue light when engaged in direct law enforcement activities. International COLREGS have no equivalent provision for law enforcement light signals.

Under Inland Rules, the agreement signal must match the proposal. If the proposal is two blasts (port-side passing), the agreement response is also two blasts. This creates an explicit mutual confirmation before either vessel commits to the maneuver.

Under International Rules, maneuvering signals are announcements — they communicate an action being taken. No agreement response is required or expected. This is the fundamental difference from the Inland Rules agreement signal system.

The COLREGS Demarcation Line is marked on NOAA nautical charts as a dashed magenta line. It separates the area where International COLREGS apply (seaward) from inland waters where U.S. Inland Navigation Rules apply.

Three red lights vertically indicate a Vessel Constrained by Draft (CBD) under International COLREGS. This category does not exist under U.S. Inland Rules, so this light configuration would only be encountered in international waters.

Under Inland Rules, the maneuvering signal is a proposal, not an announcement. The proposing vessel is waiting for an agreement (same signal back) or disagreement (five short blasts) before committing to the maneuver. Silence leaves the situation ambiguous and creates risk.

The crossing rule (Rule 15) — that a vessel approaching from the starboard side has right of way — is identical under both International COLREGS and U.S. Inland Rules. The CBD category, agreement signals, and some lighting configurations differ between the two.

International COLREGS apply immediately upon crossing the COLREGS Demarcation Line seaward. There is no transition zone — the switch is instantaneous at the line. The Demarcation Line does not correspond to the 3 or 12-mile territorial sea boundary.

'Fife' replaces 'five' because in some accents 'five' can be misheard as 'fire' — a word with very different implications at sea. 'Niner' replaces 'nine' to distinguish it from the German 'nein' (no), preventing a critical misunderstanding on international channels.

Zulu is used as the phonetic reference for UTC (Coordinated Universal Time), also known as Greenwich Mean Time (GMT). '1400 Zulu' means 1400 UTC. All official maritime logs and communications use Zulu time to eliminate confusion across time zones.

The Alpha flag flown alone means 'I have a diver down; keep well clear and proceed at slow speed.' It must be flown whenever a diver is in the water and signals other vessels to give the area a wide berth to avoid injuring the diver with propeller wash or wake.

The Quebec (Q) flag signals that the vessel is healthy and requests free pratique — official clearance to proceed into port after arriving internationally. It indicates the vessel has not yet cleared customs or immigration. Once clearance is granted, the flag is lowered.

Channel 70 is reserved exclusively for Digital Selective Calling (DSC) digital transmissions. Voice transmissions on Ch 70 interfere with the digital distress and calling system that automatically relays vessel MMSI and GPS position in emergencies.

'Out' means the conversation is complete and you are closing the channel — no reply is expected. 'Over' means you have finished speaking but are awaiting a reply. Using 'Over and Out' is a redundant contradiction — avoid it.

The NATO phonetic alphabet spells 'Juliett' with two t's. This is the correct phonetic word for the letter J and is the one recognized by the International Radiotelephony Spelling Alphabet used in maritime communications.

The Oscar flag means 'man overboard.' If you see Oscar flying on any vessel, that vessel has someone in the water and requires assistance. This flag must be immediately recognizable — it is a life-safety signal.

Channel 16 is for hailing only. Once contact is established, both vessels agree to move to a working channel for the actual conversation. Conducting extended conversations on Ch 16 blocks the channel for distress calls.

A DSC distress call automatically transmits the vessel's MMSI (Maritime Mobile Service Identity), GPS position (if a GPS is connected to the radio), and vessel identity — without the crew needing to speak. This is why MMSI registration and GPS integration are critical for DSC to be effective.

The Quebec flag (solid yellow) means the vessel is healthy and requests free pratique — clearance to enter port after arriving internationally. It indicates the vessel has not yet cleared customs and is a standard requirement for any vessel arriving from a foreign country.

Green is the starboard (right) sidelight. If you see green on your starboard side, that vessel's starboard side is facing you — it is heading from your left to your right across your bow. You are looking at its port quarter, approaching from the left side of its path.

Rule 25 requires a sailing vessel proceeding under sail and engine to display a cone, point downward, forward. This day shape signals that the vessel has lost its sailing vessel status in the hierarchy and is now classified as power-driven.

A white masthead (steaming) light plus sidelights is the signature of a power-driven vessel underway. No second higher masthead light means it is under 50 meters. A sailing vessel would show sidelights and stern light but no masthead light.

The white stern light (135° arc) is visible from dead astern. If you see only a white light and it is the stern light (no sidelights visible), you are behind the vessel, in the overtaking zone. You are the overtaking vessel and must keep clear.

A cone point downward displayed forward on a sailing vessel indicates it is proceeding under sail and engine — and is therefore classified as a power-driven vessel in the COLREGS hierarchy. It no longer has sailing vessel right-of-way priority.

Ball-diamond-ball displayed vertically is the day shape for a vessel restricted in ability to maneuver (RAM). It is the daytime equivalent of red-white-red lights. This vessel has greater right of way than power-driven or sailing vessels.

A sailing vessel proceeding under sail only in daylight is not required to display any day shape. A shape is only required if the vessel is also using its engine (cone), is at anchor (ball), or has a special status like NUC or RAM.

A single white light ahead could be an anchor light (all-round white) or a stern light (135°, visible from astern). You need additional context — bearing change, distance, other lights — to determine which it is. In either case, proceed with caution.

Seeing both sidelights simultaneously means you are in the narrow zone directly ahead of the vessel where both 112.5° arcs overlap. The vessel is heading toward you — this is a head-on or near head-on situation. Both vessels should alter to starboard.

Red-white-red lights arranged vertically is the light pattern for a vessel restricted in ability to maneuver (RAM). This vessel has greater right of way than power-driven and sailing vessels. Give it a wide berth.

Rule 25 requires a vessel proceeding under sail and engine to display a cone, point downward, in a position where it can best be seen. A sailing vessel using its engine without displaying this shape is non-compliant with COLREGS and is misrepresenting its status in the vessel hierarchy.

A sailing vessel underway under sail only shows sidelights and a stern light but NO white masthead (steaming) light. The absence of the white forward masthead light is what distinguishes a sailing vessel from a power-driven vessel at night.

The give-way vessel must take early (before the situation becomes close) and substantial (clearly visible) action to keep well clear. The alteration must be obvious to the other vessel — a small course change is not sufficient.

The give-way vessel is making its collision-avoidance maneuver based on the assumption that the stand-on vessel will hold its course and speed. An unexpected alteration by the stand-on vessel can create — rather than prevent — a collision.

Under COLREGS, a vessel proceeding under sail and engine is classified as a power-driven vessel. The moment an engine is used for propulsion, the vessel loses its sailing vessel status — even if sails are drawing. This is the definition in Rule 3.

A vessel not under command (NUC) is at the top of the COLREGS hierarchy — it has the greatest right of way because it cannot maneuver to avoid collision. All other vessels must give way to a NUC.

A vessel constrained by draft (CBD) has higher right of way than a sailing vessel. Additionally, Rule 9 requires vessels in narrow channels to not impede vessels that can only navigate safely within the channel. Both rules require the sailing vessel to keep clear.

Rule 14 (Head-On) requires both power-driven vessels to alter course to starboard so that each passes on the other's port side. This is the only encounter situation where both vessels simultaneously give way.

Rule 12 (Sailing Vessels): when two sailing vessels are approaching, the vessel on the port tack gives way to the vessel on the starboard tack. You are on port tack, so you give way.

Rule 13 (Overtaking) overrides the vessel hierarchy. Any vessel overtaking another must keep clear, regardless of vessel type. A sailing vessel overtaking a power-driven vessel must give way to the power-driven vessel until fully past and clear.

Rule 15 (Crossing): the vessel that has the other on its starboard side is the give-way vessel. The other vessel is on your starboard, so you are give-way and must take action to keep clear.

Rule 17 allows — and eventually requires — the stand-on vessel to take action when the give-way vessel is clearly not acting and collision is imminent. At that point, the stand-on vessel must maneuver, preferably not to port if the give-way vessel is on its port side.

Rule 13 (Overtaking) overrides all other rules including the vessel hierarchy. Any vessel in the overtaking position must keep clear until it is finally past and well clear. A sailing vessel overtaking a power-driven vessel is the give-way vessel.

Rule 12: when two sailing vessels are on opposite tacks, the vessel on port tack (B) gives way to the vessel on starboard tack (A). Vessel A is the stand-on vessel.

Rule 14 (Head-On): both vessels alter course to starboard, passing each other on their port sides. This is the only encounter type where both vessels simultaneously give way. When in doubt whether a situation is head-on or crossing, treat it as head-on.

Under International Rules, two short blasts means 'I am altering my course to port.' It is an announcement of a maneuver already being made. Under Inland Rules the meaning shifts to 'I intend to pass you on my port side' and requires an agreement signal.

Three short blasts means the vessel's engines are operating astern (in reverse). It is an engine signal, not necessarily a movement signal — the vessel may still be moving forward through the water while decelerating.

A sailing vessel underway in restricted visibility sounds one prolonged blast followed by two short blasts, repeated every 2 minutes. This same signal is used by NUC, RAM, CBD, fishing vessels, and vessels towing — it indicates a vessel whose maneuverability may be limited.

A power vessel underway and making way in restricted visibility must sound one prolonged blast at intervals of not more than 2 minutes. This is the standard fog signal interval for most vessel types.

The doubt or danger signal may be used any time you are uncertain of another vessel's intentions or believe a risk of collision is developing. It is proactive — you do not wait until the situation is critical. Its purpose is to signal doubt early enough for both vessels to take action.

Distress signals are governed by COLREGS Annex IV and are reserved for life-threatening emergencies. COLREGS sound signals (Rules 34 and 35) govern maneuvering intentions and restricted visibility. Using a distress signal in a non-emergency situation is itself a violation of maritime law.

Under International Rules, one short blast is an announcement: 'I am altering my course to starboard.' Under Inland Rules, the meaning shifts to 'I intend to leave you on my port side' and requires an agreement signal.

An anchored vessel in restricted visibility rings its bell rapidly for about 5 seconds at intervals of not more than 1 minute. Vessels over 100 meters must follow the bell with a rapid gong rung aft.

Under Inland Rules, the agreement signal must match the proposal signal. If the proposal is one blast, the agreement is one blast. If the other vessel disagrees or is in doubt, it sounds five or more short rapid blasts.

One prolonged blast followed by two short blasts is the fog signal for sailing vessels underway, NUC vessels, RAM vessels, CBD vessels, fishing vessels, and vessels towing or being towed. It broadly indicates vessels with restricted maneuverability.

Vessels less than 12 meters are exempt from the specific fog signal requirements but must still make some efficient sound signal at intervals of not more than 2 minutes. A handheld air horn satisfies this requirement.

COLREGS creates a shared behavioral framework so that when any two vessels approach each other, both crews can predict what the other will do. Without shared rules, each crew would be guessing — with potentially fatal results.

The 1972 Convention on the International Regulations for Preventing Collisions at Sea entered into force in July 1977. This replaced earlier fragmented rule sets that had different standards across nations.

COLREGS applies to all vessels — regardless of size, type, or nationality — on the high seas and waters connected to and navigable by seagoing vessels. A 20-foot recreational sailboat is subject to the same rules as a supertanker.

The COLREGS Demarcation Line, shown as a dashed magenta line on US nautical charts, separates the jurisdictions. Seaward of the line: International COLREGS. Landward of the line: US Inland Navigation Rules.

Part B (Rules 4–19) contains the steering and sailing rules — including look-out, safe speed, give-way and stand-on obligations, head-on, crossing, and overtaking situations. This is the 'rules of the road' section.

Rule 2 acknowledges that no set of rules can anticipate every situation. It allows — and in fact requires — departure from the rules when strict compliance would itself create danger. The rules are the floor, not a ceiling that prevents good seamanship.

Part C (Rules 20–31) specifies all light and shape requirements — what colors, what arcs of visibility, when they must be shown, and the requirements for different vessel types.

COLREGS is maintained by the International Maritime Organization (IMO), the UN specialized agency for maritime safety. The USCG enforces the rules in US waters but did not author them.

COLREGS applies to all vessels on the high seas and connected navigable waters regardless of size, type, or flag. Both vessels are equally bound by the rules.

The COLREGS Demarcation Line divides US waters: International COLREGS apply seaward of the line; US Inland Navigation Rules apply landward. The line is shown on NOAA charts as a dashed magenta line.

Rule 2 acknowledges that good seamanship may sometimes require departing from specific rules to avoid a collision. It doesn't excuse careless navigation — it recognizes that rigid rule-following can itself create danger in unusual situations.

Part B (Rules 4–19) is the operational heart of COLREGS — it covers look-out, safe speed, risk of collision assessment, give-way and stand-on responsibilities, head-on, crossing, and overtaking situations.