Aids to Navigation — IALA-B Buoyage in U.S. Waters

What the rule requires

The colour, shape, number and light characteristic of a lateral aid tell you which side to pass it on, and the whole scheme is anchored to one condition: the vessel is proceeding in the Conventional Direction of Buoyage. 33 CFR §62.21 states that lateral aids indicate on which side of a vessel an aid should be passed when proceeding in that direction. Get the direction wrong and every colour on the chart reverses meaning.

Within Region B the scheme is red on the right returning from sea, with even numbers on red and odd numbers on green Bowditch Ch. 5 §501.

Establishing the Conventional Direction of Buoyage

Normally it is the direction in which a vessel enters navigable channels from seaward and proceeds toward the head of navigation . Most channel questions resolve there and go no further.

Where there is no route leading from seaward — a coastwise passage, for instance — the direction generally follows a clockwise direction around land masses. The regulation names the three cases a candidate will actually be asked about: proceeding southerly along the Atlantic Coast, from Florida to Texas along the Gulf Coast, and northerly along the Pacific Coast are all considered proceeding in the Conventional Direction of Buoyage.

In some instances the direction must be arbitrarily assigned. Where doubt exists, consult the charts and other nautical publications rather than reasoning it out from the geography.

You are running north up the Pacific Coast off Oregon, well outside any harbour approach. On which hand do you leave a red aid?

To starboard. There is no route leading from seaward here, so the Conventional Direction of Buoyage runs clockwise around the land mass, and northerly along the Pacific Coast is with that direction. Red is left to starboard when proceeding in the Conventional Direction of Buoyage. Southbound on that same coast, red would be left to port.

Region B and the Region A exception

All navigable waters of the United States follow IALA Region B, except U.S. possessions west of the International Date Line and south of 10 degrees north latitude, which follow Region A . Only the lateral aids vary in Region A; non-lateral aids are the same as those used in Region B. Which scheme is in effect for a given area is determined from the appropriate nautical charts and publications.

Region B is not a U.S.-only arrangement. Canada, Japan, the Caribbean, Korea and the Philippines are in it as well Light List — light-characteristic (R).

The aid does not work without the chart

The U.S. Aids to Navigation System is designed for use with nautical charts, and the exact meaning of an aid may not be clear unless the appropriate chart is consulted . The chart shows the relationship of that individual aid to channel limits, obstructions, hazards to navigation, and to the total system. Topographic maps, aeronautical charts and atlases do not carry soundings and submarine features and cannot substitute.

The system is primarily lateral, employing colours, shapes, numbers and light characteristics to mark the limits of navigable routes, and it is supplemented by non-lateral aids where appropriate. Aids to navigation as a class include lights, buoys, beacons and electronic aids . Green and red are the two lateral light colours, abbreviated G and R in the Light List Light List — light-characteristic (G).

Discrepancies and private aids

Aids are maintained to a reasonable degree of reliability, but the rigors of the marine environment and equipment failures do cause discrepancies . The Coast Guard makes reasonable efforts to inform the navigator of known discrepancies and to correct them within a reasonable period, depending on resources. A temporary aid providing different but similar service may be deployed until permanent repairs are made, and notification of such temporary changes is made through the notice to mariners system.

Private aids call for extra caution on two counts: they are often established to serve the needs of specific users rather than general navigation, so their purpose may not be obvious to a casual user, and discrepancies to them are often detected, reported and corrected less promptly than discrepancies to Coast Guard aids.

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Telling it apart

Which publication answers the question

The separating criterion is what kind of information it carries and how current it is. Exam questions phrase this as "where would you find…", and the four publications are close enough that candidates guess.

• Light List — published by the Coast Guard. Lists federal aids and those private aids deemed important to general navigation, with a physical description of each aid and its location 33 CFR §62.21. Most often misfiled: candidates go here for a temporary change or a reported danger.
• United States Coast Pilot — published by the National Ocean Service. Local navigation regulations, channel and anchorage peculiarities, dangers, climatological data, routes, and port facilities. Most often misfiled: anything about the physical description of a single buoy.
• Local Notice to Mariners — published by local Coast Guard District Commanders. Changes to aids to navigation, reported dangers, scheduled construction or other disruptions, and chart corrections.
• Notice to Mariners — published by the National Geospatial-Intelligence Agency. A national publication, similar in kind to the Local Notice, providing oceangoing vessels significant information on national and international navigation and safety.
• Broadcast Notice to Mariners — the most timely of the set. It updates the Local Notice with more timely information, and the mariner monitors VHF-FM channel 16 to locate Coast Guard Marine Information Broadcasts.

If a question asks for the most current information on a discrepancy, the answer is the broadcast, not the printed notice.

A buoy at the entrance to your harbour has been reported off station this morning. Which publication is your best source before you sail this afternoon?

The Broadcast Notice to Mariners, monitored on VHF-FM channel 16. It updates the Local Notice to Mariners with more timely information. The Local Notice does carry changes to aids and reported dangers, but the broadcast is the more timely of the two for something reported the same day.

Federal against private aids

The criterion is who the aid was established to serve.

• Coast Guard aids — established for general navigation. Discrepancies are detected, reported and corrected comparatively promptly.
• Private aids — often established to serve specific users, so the purpose may not be obvious; discrepancy correction is often less prompt. Most often misfiled: a candidate assumes every charted aid is federally maintained and gives it the same weight in a fix.

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Working a question

You are running a small passenger vessel southbound along the Atlantic Coast off Georgia, offshore of any harbour approach, and you raise a red lighted aid ahead. Then you turn in and run up a buoyed channel to a marina.

1. Establish the region. These are navigable waters of the United States, not a possession west of the International Date Line and south of 10°N, so Region B applies. Red on the right returning from sea, even on red, odd on green.
2. Establish the Conventional Direction of Buoyage for the leg you are on. Offshore, coastwise, there is no route leading from seaward. The direction follows a clockwise direction around the land mass, and proceeding southerly along the Atlantic Coast is in the Conventional Direction of Buoyage.
3. Compare your direction of transit to it. Southbound matches. You are proceeding in the Conventional Direction of Buoyage, so the lateral aids apply in their normal sense.
4. Apply the scheme. Leave the red aid to starboard. Confirm with the number: a red aid carries an even number.
5. Confirm against the chart. The aid's exact meaning follows from its relationship to the channel limits and any charted obstruction, which only the chart shows.
6. Re-establish the direction when you turn in. Entering the channel from seaward toward the head of navigation is the Conventional Direction of Buoyage for that channel, so red stays to starboard on the way in. Outbound from the marina later, you are proceeding against it and red is left to port.

Step 3 is the one that decides the question. A candidate who skips it applies the colour scheme to whatever heading the vessel is steering and gets the reciprocal.

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Where candidates lose the point

• Reads "returning" as returning to their own berth. A vessel outbound for the sea buoy is not returning by anyone's reckoning, and candidates answer red to starboard anyway out of habit. The trigger in the rule is the Conventional Direction of Buoyage, which is entry from seaward toward the head of navigation. Outbound, you are proceeding against it and the sides reverse.
• Answers "Region B" for everything under U.S. jurisdiction. The exception is written into the regulation by geography: possessions west of the International Date Line and south of 10 degrees north latitude follow Region A. A candidate who has only ever heard "the U.S. uses Region B" will miss the question that names a Pacific possession.
• Over-corrects on Region A and reverses the non-lateral aids too. Only lateral aids vary in Region A. Non-lateral aids are the same as those used in Region B.
• Inverts the numbering. Even numbers on red, odd on green. Candidates who memorise only the colours have nothing left to check their answer against, and the number is the cheapest cross-check available.
• Treats an off-station or missing aid as a charting error. Discrepancies occur, and a temporary aid providing different but similar service may be in place until permanent repairs are made — announced through the notice to mariners system, which is why the question about a discrepancy is a publications question.
• Answers a "which side do I pass" question from the buoy alone. Without the chart, the aid's relationship to the channel limits, obstructions and hazards is unknown, and the regulation says as much.

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Check yourself

You are outbound from a harbour, proceeding seaward down a buoyed channel in Chesapeake Bay. On which hand do you leave the green odd-numbered aids?

To starboard. The Conventional Direction of Buoyage for that channel is inbound from seaward toward the head of navigation. Proceeding seaward you are running against it, so the normal sense reverses: green odd-numbered aids to starboard, red even-numbered aids to port.

You are operating in a U.S. possession in the Pacific, west of the International Date Line and at 7°N. What buoyage scheme is in effect, and what does that change?

IALA Region A. It changes the lateral aids, which vary from the Region B scheme. It does not change the non-lateral aids, which are the same as those used in Region B. Confirm the scheme in effect from the appropriate charts and publications for the area.

You are making a coastwise passage from Florida toward Texas along the Gulf Coast. Are you proceeding in the Conventional Direction of Buoyage?

Yes. With no route leading from seaward, the Conventional Direction of Buoyage generally follows a clockwise direction around land masses, and the regulation names the Florida-to-Texas run along the Gulf Coast as an example of proceeding in that direction. Red is left to starboard.

You need the physical description and exact location of a lighted aid marking the approach to an unfamiliar port. Which publication?

The Light List, published by the Coast Guard. It lists federal aids and those private aids deemed important to general navigation, including a physical description of the aids and their locations. Channel and anchorage peculiarities for that port would come from the Coast Pilot instead.

You are taking a fix using a charted buoy that the chart identifies as privately maintained. What is your concern?

Private aids are often established to serve the needs of specific users rather than general navigation, so the purpose may not be obvious, and discrepancies to private aids are often detected, reported and corrected less promptly than discrepancies to Coast Guard aids. Weigh the fix accordingly and verify against other aids.

You are heading south along the Atlantic Coast and pass a lighted aid showing a green light. Which side of the channel does it mark relative to your track, and what number should it carry?

Southerly along the Atlantic Coast is the Conventional Direction of Buoyage, so you are proceeding in the normal sense: the green aid marks the port side of the route and you leave it to port. It should carry an odd number. If the number is even, re-examine the aid and the chart before acting on it.

An aid is found to be missing from its charted position. How would you expect to learn what has been put in its place?

Through the notice to mariners system. The Coast Guard makes reasonable efforts to inform the navigator of known discrepancies and to correct them within a reasonable period, and where a temporary aid providing different but similar service is deployed until permanent repairs are made, notification of that temporary change is made through the notice to mariners system.