Shom L Nautical Chart – Atlantic Ocean

Shom L Atlantic Ocean nautical chart: paper cartography for navigation

The Shom L Atlantic Ocean nautical chart is a folded paper nautical chart designed to prepare for and support navigation in the different Atlantic areas covered by Shom, the French Hydrographic and Oceanographic Service. It can be used to plan a route, study a coastline, identify navigation hazards, locate ports, channels, passes, anchorages, landmarks and aids to navigation, and obtain a detailed cartographic representation of the navigated area.

The key characteristic of the Shom L chart is its format. Unlike a Shom C nautical chart, which is generally kept rolled, the Shom L chart is folded to A4 size, approximately 21 × 29.7 cm. Once unfolded, it provides a large cartographic surface, generally close to A0 size, approximately 84 × 119 cm. The paper support is designed to maintain good readability while making storage and transport on board easier.

The Shom L range dedicated to the Atlantic Ocean covers very different maritime environments: the French Atlantic coast, Brittany, the Bay of Biscay, the Iberian Peninsula, the North Atlantic, transatlantic passages and certain routes towards the French West Indies. The range includes charts covering areas around Bayonne, Capbreton, Brest, Lorient, La Rochelle and Nantes–Saint-Nazaire, as well as charts intended for longer-distance navigation.

A Shom L nautical chart for planning navigation in the Atlantic

The Atlantic Ocean is an exceptionally large navigation area. The cartographic requirements are not the same for coastal navigation in Brittany, an approach to the Bay of Biscay, a transatlantic crossing between Europe and the Caribbean, or navigation around Martinique and Guadeloupe.

The Shom L nautical chart meets different route-planning requirements through its range of scales and geographical areas.

For coastal navigation, the chart can be used to study soundings, depth contours, wrecks, rocks, shoals, lights, aids to navigation and harbour approaches. For offshore navigation, it provides a geographical overview of the route and helps prepare the different stages of a voyage.

Scale remains essential. A chart covering a large part of the Atlantic makes it possible to visualise a long-distance route, whereas a larger-scale chart provides more detail for a coastal or harbour approach.

The French Atlantic coast

The French Atlantic coast represents an important part of Shom L cartography.

From Brittany to the Basque Country, coastal configurations vary considerably. Navigators may need to prepare navigation around Brest, Ushant, Lorient, Belle-Île, the Gulf of Morbihan, La Rochelle, Île de Ré, the Gironde estuary, Bayonne or Capbreton.

Shom L charts can be used in particular to study harbour approaches and coastal areas. Certain references cover the approaches to Bayonne, the port of Capbreton, the approaches to Brest and areas of southern Brittany.

These charts are particularly useful for preparing coastal navigation while taking into account the coastline, isolated hazards, soundings and aids to navigation.

Brittany, the English Channel and the Iroise Sea

Brittany is a particularly complex area for navigation. Currents, tides, numerous islands, rocks, shoals and channels require careful interpretation of the nautical chart.

The areas around Brest, Île Vierge, Pointe de Penmarc'h, Lorient, Groix, Belle-Île and the Gulf of Morbihan illustrate this diversity.

A Shom L nautical chart can be used to prepare navigation between the different ports and anchorages of southern Brittany, study approaches to Brest or plan a route along the Breton coast.

The ports of Brest, Lorient, Concarneau, Saint-Malo, Vannes, La Trinité-sur-Mer and Le Croisic are examples of reference points for regional navigation.

Bay of Biscay, Nouvelle-Aquitaine and the Basque Country

Further south, the Bay of Biscay presents a different maritime environment. Navigators may be concerned with the areas around La Rochelle, Rochefort, Royan, Bordeaux, Arcachon, Bayonne, Saint-Jean-de-Luz and Hendaye.

The approaches to Bayonne and the area around Capbreton are covered by specific Shom L charts.

In the Bay of Biscay, the nautical chart is an important support for planning coastal or offshore routes. It helps identify the different cartographic elements required to understand the area: soundings, seabed information, hazards, aids to navigation, landmarks and harbour infrastructure.

For navigation between France and the Iberian Peninsula, several charts may be required depending on the selected route and the level of detail needed.

Portugal, the Iberian Peninsula and the North Atlantic

Atlantic navigation is not limited to the French coast. Depending on the references and scales, Shom cartography can also support longer-distance navigation.

Portugal is an important area for navigators heading towards the Canary Islands, Cape Verde or the Caribbean. The ports of Lisbon, Porto, Cascais, Figueira da Foz, Lagos and Portimão are well-known points along Atlantic routes.

Route planning may then incorporate Madeira, the Canary Islands and Cape Verde depending on the selected itinerary.

For an Atlantic crossing, cartography should be organised according to different levels: a general or ocean passage chart for the offshore route, coastal charts for approaches to the various stopovers, and larger-scale charts for ports and anchorages.

France–Caribbean routes and the tropical Atlantic

Some Shom L Atlantic charts also cover navigation between France and the French West Indies. Reference 6561L, for example, covers the North Atlantic on the France–Caribbean route.

This coverage is particularly relevant to navigators preparing a transatlantic passage, especially when heading towards Martinique or Guadeloupe.

In the French Caribbean, ports and navigation areas may include Fort-de-France, Le Marin, Pointe-à-Pitre, Basse-Terre, Les Saintes, Marie-Galante and the various anchorages around the islands.

The nautical chart can then serve as an additional route-planning tool alongside electronic navigation systems. It provides a broad geographical view of the crossing and helps prepare approaches to the various coastal areas.

What information is shown on a Shom L chart?

Depending on the geographical area and scale, a Shom L chart can contain a wide range of information essential for navigation:

• soundings and depths;

• depth contours;

• seabed characteristics where represented;

• rocks and shoals;

• wrecks;

• reefs;

• lights and light characteristics;

• buoys and other aids to navigation;

• landmarks and prominent features;

• channels and passes;

• regulated areas and limits;

• ports and harbour facilities;

• anchorages;

• coastal structures;

• information required for route planning.

The amount of information available depends directly on the chart scale. A harbour or approach chart will provide considerably more detail than a chart designed to represent a large navigation area.

The importance of scale for an Atlantic nautical chart

Scale is one of the first criteria to consider when selecting a nautical chart.

A small-scale chart represents a large geographical area. It is particularly suitable for offshore route planning or for obtaining an overall view of a transatlantic crossing.

A large-scale chart represents a smaller area but with considerably more detail. It is particularly suitable for harbour approaches, channels, passes, anchorages and complex coastal areas.

For an Atlantic crossing, several complementary charts are therefore often required. A passage chart can be used to plan the overall route, while coastal and harbour charts take over when approaching stopovers.

Differences between Shom C, L, G, Z and Raster charts

The Shom L chart is therefore essentially another presentation of standard Shom nautical cartography. For the same chart number, the L chart contains the cartographic information of the corresponding C chart, but is folded to A4 size.

The G chart has a different purpose: it provides specific information about seabed characteristics and does not replace a conventional nautical chart.

The Z chart concerns exercise and firing areas.

The Raster chart is a digital version of the nautical chart in the form of a georeferenced image. Shom's RasterMarine products include several scale ranges and are intended for digital cartographic use. (Data Shom)

Shom L or Shom C for navigation in the Atlantic?

The choice between a Shom L and a Shom C mainly depends on the preferred format.

The C chart is particularly suitable for use on a chart table when a large sheet can remain fully unfolded. The L chart is more convenient when charts need to be transported, classified or stored in a limited space.

For a long Atlantic voyage, the folded format can offer a practical advantage: several charts corresponding to the different stages of a journey can be stored more easily on board.

The cartographic content nevertheless remains linked to the chart reference and scale. The choice should therefore begin with the geographical area and the level of detail required for navigation.

The Shom L chart when preparing an Atlantic crossing

An Atlantic crossing requires structured cartographic preparation.

Before departure, the chart can be used to:

• define the different stages of the voyage;

• visualise the overall route;

• identify departure and destination ports;

• prepare coastal approaches;

• identify areas presenting navigation hazards;

• organise the charts required for the different phases of the voyage;

• complement route planning carried out with electronic navigation equipment.

For a Europe–Caribbean route, for example, preparation may include the French coast, the Iberian Peninsula, Atlantic islands and the French West Indies. Ports such as La Rochelle, Bayonne, Lisbon, Las Palmas, Santa Cruz de Tenerife, Mindelo, Fort-de-France or Pointe-à-Pitre may serve as reference points depending on the chosen route.

Cartography adapted to different types of navigation

The Shom L Atlantic Ocean nautical chart can meet a variety of navigation requirements:

• coastal navigation in Brittany;

• navigation in the Bay of Biscay;

• navigation along the French Atlantic coast;

• approaches to Atlantic ports;

• navigation towards Portugal and the Iberian Peninsula;

• preparation of an Atlantic crossing;

• navigation towards the French West Indies;

• preparation of routes between France and Martinique or Guadeloupe;

• navigation around Martinique and Guadeloupe;

• study of anchorages and harbour approaches;

• preparation of offshore routes.

Paper nautical charts therefore remain a structured support for route planning, particularly when several geographical areas and different scales need to be combined.

Shom L Atlantic Ocean nautical chart: choosing the right reference

When selecting a Shom L Atlantic chart, several elements should be checked:

• the chart number;

• its title;

• the geographical area covered;

• the scale;

• the ports concerned;

• the islands and archipelagos represented;

• the required harbour approaches;

• the type of navigation planned;

• the edition and update status.

This verification is particularly important in the Atlantic, where requirements can differ considerably between coastal navigation in France and an ocean crossing towards the Caribbean.

Conclusion

The Shom L Atlantic Ocean nautical chart is a paper cartographic solution particularly suited to navigators looking for a large cartographic surface while retaining a compact format when the chart is folded.

The range covers very different environments, from the French Atlantic coast and the Bay of Biscay to the North Atlantic and certain routes towards the Caribbean. The areas around Brest, Lorient, La Rochelle, Bayonne, Capbreton, Lisbon, the Atlantic islands, Fort-de-France and Pointe-à-Pitre illustrate the diversity of navigation that may require appropriate nautical cartography.

The Shom L format provides a large cartographic surface once unfolded while making storage on board easier. When preparing an Atlantic voyage, however, the choice should always take into account the geographical coverage, scale, type of navigation and level of detail required.

The Shom L chart can therefore form part of comprehensive navigation preparation combining nautical charts, sailing directions, atlases, navigation manuals and documentation appropriate to the planned route.

FAQ – Shom L Atlantic Ocean nautical chart

What is a Shom L Atlantic Ocean nautical chart?

It is a Shom paper nautical chart covering a specific area of the Atlantic Ocean and presented in a folded format. It can be used to prepare and support different types of navigation, from coastal navigation to offshore passages.

What is the format of a Shom L chart?

The Shom L chart is folded to A4 size, approximately 21 × 29.7 cm. When unfolded, it provides a large cartographic surface, generally close to A0 size.

What is the difference between a Shom C and a Shom L chart?

For the same chart number, C and L charts contain the same cartographic information. The main difference is the presentation: the C chart is generally rolled, whereas the L chart is folded to A4 size.

Which Atlantic areas are covered by Shom L charts?

The range includes areas of the French Atlantic coast, Brittany, the Bay of Biscay, the Iberian Peninsula, the North Atlantic and certain routes between France and the Caribbean.

Are there Shom L charts for Brittany?

Yes. Several references cover areas including the approaches to Brest, Île Vierge, Penmarc'h, Lorient, Groix, Belle-Île and the Gulf of Morbihan.

Are there Shom L charts for Bayonne and Capbreton?

Yes. The range includes references covering the approaches to Bayonne, the port of Bayonne and the area around Capbreton.

Can a Shom L chart be used to prepare an Atlantic crossing?

Yes, provided that the selected reference has the appropriate scale and geographical coverage for the navigation phase concerned. A crossing will generally require several levels of cartography, particularly for coastal and harbour approaches.

Is there a Shom L chart for the France–Caribbean route?

Yes. The range includes, in particular, a reference covering the North Atlantic on the France–Caribbean route.

Which Atlantic ports may be covered by Shom L charts?

Depending on the reference, charted areas may include Brest, Lorient, La Rochelle, Bayonne, Capbreton, Saint-Nazaire and Lisbon, as well as Fort-de-France, Le Marin, Pointe-à-Pitre and Basse-Terre.

What is the purpose of the scale of a nautical chart?

Scale determines the level of detail represented. A small-scale chart covers a large area, while a large-scale chart allows a coastline, harbour, channel, pass or anchorage to be studied in greater detail.

What is a Shom G chart?

A Shom G chart is a specialised chart dealing with the nature and distribution of seabed sediments. It provides information complementary to conventional nautical cartography, particularly for certain professional and fishing uses.

What is a Shom Z chart?

A Shom Z chart concerns exercise and firing areas. It identifies areas affected by certain military activities.

What is a Shom Raster nautical chart?

A Shom Raster chart is a digital version of a nautical chart in the form of a georeferenced image, such as a GeoTIFF, intended for use with compatible cartography or navigation software. Shom's digital catalogue includes georeferenced digital images derived from corresponding printed nautical charts. (Data Shom)

Is the Shom L chart suitable for coastal navigation?

Yes. Depending on its scale and geographical coverage, it can be used to prepare coastal navigation, study harbour approaches, channels, anchorages and the various hazards represented on the chart.

Why use a paper chart to prepare navigation in the Atlantic?

A paper chart provides a broad geographical view of the route and allows the navigator to work over a large cartographic surface. It can complement the electronic systems used on board and facilitate preparation of the different stages of a voyage.