Nautical Instructions – Navigation Guides and Documentation

Introduction

Nautical instructions are reference publications designed to complement the information provided by nautical charts. They describe coastlines, harbour approaches, hazards, currents, tides, buoyage, anchorages, recommended routes and the nautical characteristics of a specific maritime area.

A nautical chart provides a precise visual representation of coastlines, depths, shoals, wrecks, buoys, channels and other hydrographic features. A nautical instruction provides different information: it explains the maritime environment and draws the navigator’s attention to characteristics that should be taken into account when planning and following a route.

Nautic Way Maritime Bookshop offers a selection of nautical instructions and reference publications covering the English Channel, North Sea, Atlantic Ocean, Mediterranean Sea, Corsica, the Caribbean, French Guiana, Indian Ocean, New Caledonia and French Polynesia.

Publications from SHOM – Service hydrographique et océanographique de la Marine, the French hydrographic and oceanographic service, play a central role in this documentation. They are intended for both professional mariners and recreational sailors and provide detailed information on numerous navigation areas. The current SHOM catalogue organizes nautical instructions by major geographical areas: English Channel, Atlantic, Mediterranean, overseas territories and foreign waters.

What is a nautical instruction?

A nautical instruction is a navigation document containing information useful for understanding and preparing navigation in a specific geographical area.

It does not replace a nautical chart. It complements it.

Some information is difficult to represent on a chart or needs to be explained in greater detail. A nautical instruction may therefore describe:

• the configuration and nature of coastlines;

• prominent landmarks used for position fixing;

• navigation hazards;

• shoals and particular areas;

• channels and passages;

• currents and local phenomena;

• tides;

• maritime buoyage;

• recommended or regulated routes;

• anchorages;

• harbour approaches;

• characteristics of ports and their approaches;

• services available at certain ports;

• local meteorological and oceanographic conditions;

• specific precautions to be taken in certain areas.

SHOM defines nautical instructions as publications providing useful information that does not appear on nautical charts or is represented too briefly on them.

SHOM Nautical Instructions: a reference for navigation

SHOM nautical instructions are an important reference for navigation along the French coast and in several maritime areas covered by French hydrographic documentation.

The collection includes nautical instructions covering:

• the French English Channel coast;

• the Brittany coast and Atlantic coast;

• the French Atlantic coast to the Spanish border;

• the French Mediterranean coast;

• Corsica;

• certain foreign coasts;

• the French West Indies and French Guiana;

• Saint-Pierre-et-Miquelon;

• New Caledonia;

• French Polynesia;

• certain areas of the Indian Ocean.

French references C21, C22, C23, C24, D21, D22 and D23 make it possible to select documentation corresponding to the geographical area being navigated.

SHOM nautical instructions are currently distributed in digital PDF format. Publications are associated with a validity period and may receive updates during their access period, depending on the conditions applying to each publication.

Nautical Instructions for the English Channel and North Sea

The English Channel is an area where nautical documentation is particularly important. Tidal currents can be strong, shipping traffic is heavy and the coastline contains numerous channels, banks, shoals, headlands and ports.

For navigation between Dunkirk, Calais, Dieppe, Le Havre, Cherbourg, Granville and Saint-Malo, nautical instructions complement the information shown on nautical charts.

The western part of the English Channel then leads towards Brittany, including Saint-Brieuc, Paimpol, Roscoff, Brest, Ouessant, Douarnenez and Pointe du Raz.

For navigation in British waters, the documentation can be supplemented by hydrographic and cartographic publications from Admiralty, which are widely used for the United Kingdom coast.

In the southern North Sea, navigation around the French, Belgian, Dutch and German coasts also requires a good understanding of traffic separation schemes, regulated routes, currents and port approaches.

Nautical Instructions for Brittany and the Atlantic

The French Atlantic coast presents a wide variety of navigation conditions.

Between Brest and Pointe de Penmarc’h, navigators encounter a highly indented coastline, islands, archipelagos, channels and areas affected by sometimes significant tidal currents.

Further south, navigation may involve Concarneau, Lorient, Belle-Île, Quiberon, Île d’Yeu, La Rochelle, Royan, the Gironde estuary, Arcachon, Bayonne and Saint-Jean-de-Luz.

Nautical instructions are particularly useful for preparing:

• coastal sailing in Brittany;

• a passage across the Bay of Biscay;

• an approach to an unfamiliar port;

• a cruise between Atlantic islands;

• a route towards Spain and Portugal;

• a passage towards Madeira, the Canary Islands or the Azores.

SHOM covers the French western coast with, among others, instructions C23 and C24. C23 covers the area between Pointe de Penmarc’h and Fromentine, while C24 covers the coast from Île d’Yeu to the Spanish border.

Nautical Instructions in the Mediterranean

The Mediterranean Sea also has its own navigation characteristics: rugged coastlines, headlands, islands, local winds, anchorages, shipping traffic and numerous harbour areas.

For the French coast, nautical instructions cover areas between the Spanish border, the Gulf of Lion, Provence and the Italian border.

Navigators may therefore prepare passages and port calls at Port-Vendres, Marseille, Toulon, Saint-Tropez, Cannes, Antibes or Nice.

Corsica has a dedicated publication, D23, covering the island’s coastline. It is relevant to navigation around Calvi, Saint-Florent, Bastia, Porto-Vecchio, Bonifacio, Propriano and Ajaccio.

For international Mediterranean navigation, the information can be supplemented by publications from the hydrographic offices of the countries concerned and by Admiralty or NV Charts cartography, depending on the area and navigation system being used.

Nautical Instructions for Foreign Coasts

Nautical documentation is not limited to French waters.

Some SHOM instructions also cover foreign areas, particularly in the Mediterranean. Instruction D6, for example, describes the coasts of Morocco, Algeria, Tunisia, Lebanon and Syria.

This type of documentation is particularly useful for sailors undertaking an international Mediterranean cruise, with possible calls at Tangier, Algiers, Tunis, Valletta or Beirut, as well as many other Mediterranean ports.

For other countries, publications from national hydrographic offices and specialist publishers complement French documentation. Admiralty cartography is widely used for international navigation.

Nautical Instructions for the Caribbean and Oceans

Nautical instructions also cover major ocean routes and overseas territories.

In the French West Indies and French Guiana, documentation may support navigation around Fort-de-France, Pointe-à-Pitre, Basse-Terre and Saint-Martin, as well as the various islands of the Caribbean.

For an Atlantic crossing from the Canary Islands or Cape Verde to the Caribbean, nautical instructions are primarily used to prepare coastal approaches and port calls. They should be used together with nautical charts covering the entire route.

SHOM also provides nautical instructions for Saint-Pierre-et-Miquelon, New Caledonia, French Polynesia, Wallis and Futuna, Clipperton and certain areas of the Indian Ocean.

For navigation in Polynesia, documentation may cover areas such as Tahiti, the Society Islands, the Tuamotu Archipelago and the Marquesas Islands. In New Caledonia, it supports navigation around Nouméa and the various areas of the archipelago.

How to Use a Nautical Instruction

A nautical instruction is primarily used when planning a route, preparing a port call and approaching an unfamiliar area.

Before departure, the navigator can study:

• the general configuration of the coastline;

• reported hazards;

• difficult passages;

• currents;

• harbour approaches;

• possible anchorages;

• regulated areas;

• local weather characteristics;

• navigation recommendations.

When approaching a port, the nautical instruction helps place the information shown on the chart into context.

For example, when approaching Brest, the navigator does not simply identify the entrance to the Goulet on the chart. The documentation can also be consulted for information about the approach, landmarks, currents, traffic and local characteristics.

The same principle applies when approaching Marseille, Ajaccio, Cherbourg, La Rochelle or Saint-Malo.

Nautical Instruction and Nautical Chart: Two Complementary Documents

The best way to understand the role of a nautical instruction is to distinguish the functions of the different documents.

The nautical chart mainly answers the question: where are the features that matter for navigation?

The nautical instruction answers more specifically: what are the characteristics of this area and what precautions should be taken?

This complementarity is fundamental.

SHOM emphasizes that nautical instructions complement charts and are an integral part of nautical documentation.

For comprehensive navigation preparation, the navigator can therefore combine:

• paper or digital nautical charts;

• nautical instructions;

• the List of Lights;

• tide tables;

• current information;

• Notices to Mariners;

• maritime safety information;

• regulations applicable to navigation.

Nautical Instructions and Up-to-Date Nautical Information

Nautical information changes. A light may be modified, a buoy may be moved, a new hazard may be identified, a channel may be altered or local regulations may evolve.

For this reason, nautical documentation must be kept up to date.

SHOM explains that nautical information includes data relating to coastlines, buoyage, regulated areas, offshore installations, ports and their approaches, radio services, tides, currents and newly identified hazards.

Digital nautical instructions benefit from update mechanisms appropriate to their validity period. For example, the C22 instruction is currently supplied with a validity period of 365 days and access to corrected versions during that period.

Nautical Instructions for Professionals and Recreational Sailors

Nautical instructions are intended for a wide range of users.

They are relevant to:

• cruising sailors;

• motorboat users;

• professional skippers;

• delivery crews;

• merchant vessels;

• fishermen;

• maritime schools and training centres;

• offshore sailors;

• crews preparing ocean passages.

The technical nature of these publications does not therefore make them exclusively professional documents. SHOM itself specifies that several instructions intended for professional mariners also contain substantial information useful to recreational sailors.

Conclusion

Nautical instructions are an essential part of navigation documentation. They provide detailed information about coastlines, ports, hazards, currents, tides, buoyage, anchorages and the specific characteristics of different maritime areas.

For France, SHOM nautical instructions cover the English Channel, Atlantic coast, Mediterranean and Corsica. They also extend to several overseas territories and certain foreign areas.

From Dunkirk to Cherbourg, from Brest to La Rochelle, from Marseille to Ajaccio, and from the Caribbean to French Polynesia, these publications help navigators better understand their maritime environment before and during a voyage.

They should be regarded as an essential complement to SHOM, Admiralty and NV Charts nautical charts and to the products of other hydrographic offices. The chart shows geographical and hydrographic features; the nautical instruction provides the context required to interpret them and prepare the route.

FAQ – Nautical Instructions

What are nautical instructions used for?

Nautical instructions provide useful navigation information that does not appear on nautical charts or is represented too briefly. They describe coastlines, hazards, ports, currents, tides, buoyage and anchorages.

What is the difference between a nautical chart and a nautical instruction?

A nautical chart represents the maritime environment and its hydrographic characteristics. A nautical instruction provides explanations and additional information that help the navigator understand and prepare navigation in that area.

Are SHOM nautical instructions intended for recreational sailors?

Yes. Even when they are intended for professional mariners, SHOM nautical instructions contain substantial information that is useful to recreational sailors.

Which French areas are covered by SHOM nautical instructions?

The collection includes the English Channel, Atlantic coast, Mediterranean and Corsica, with different publications corresponding to specific geographical areas.

Which nautical instruction should I choose for Brittany?

The choice depends on the exact area. The collection includes, among others, C22 for part of the northern and western coast and C23 for the western coast between Pointe de Penmarc’h and Fromentine.

Which nautical instruction should I choose for the French Atlantic coast?

References C23 and C24 cover respectively the western coast between Pointe de Penmarc’h and Fromentine, and the coast from Île d’Yeu to the Spanish border.

Which nautical instruction should I use for the French Mediterranean coast?

References D21 and D22 cover the French Mediterranean coast, while D23 is dedicated to Corsica.

Is there a nautical instruction for Corsica?

Yes. Nautical instruction D23 is dedicated to the Corsican coastline and provides information intended for both professional and recreational sailors.

Are nautical instructions available in paper format?

The SHOM nautical instructions currently offered are distributed exclusively in digital PDF format.

Are digital nautical instructions updated?

Yes. Depending on the licence, digital publications provide access to corrected versions during their validity period. The exact arrangements depend on the publication concerned.

Do nautical instructions replace nautical charts?

No. They complement nautical charts. They provide descriptive and practical information that cannot be fully represented on a chart.

Which nautical charts can be used with a nautical instruction?

Depending on the area, nautical instructions can be used with SHOM, Admiralty and NV Charts charts, as well as charts produced by the relevant national hydrographic offices.

Are nautical instructions useful for offshore navigation?

Yes. They are particularly useful for preparing coastal approaches, port calls and passages through unfamiliar areas. For an ocean passage, they are used together with documentation covering the entire route.

What information can be found in a nautical instruction?

Information may include coastlines, landmarks, hazards, currents, tides, buoyage, regulated or recommended routes, anchorages, ports, harbour approaches and certain meteorological or oceanographic characteristics.

Why should nautical instructions be kept up to date?

Because the maritime environment changes. Buoyage, hazards, installations, regulations and port access conditions may change. Up-to-date nautical documentation helps the navigator work with the latest available information.