Nautical Chart for the French Offshore Boating Licence

A nautical chart is an essential tool for preparing for the French recreational boating licence offshore extension and for understanding the basic principles of offshore navigation. It is used to determine a position, plot a course, calculate a heading, measure a distance, take currents and leeway into account, and apply the information required to plan a voyage. In France, the offshore extension allows navigation at sea without a distance limit, whereas the coastal option allows navigation up to 6 nautical miles from a shelter.

Preparing for the offshore boating licence therefore relies heavily on the ability to read and use a nautical chart. Although sailors today have access to GPS, chartplotters and electronic charts, understanding the paper chart remains fundamental for mastering the principles of navigation and checking a route independently of electronic equipment.

Why Use a Nautical Chart to Prepare for the Offshore Boating Licence?

Learning offshore navigation requires the ability to use an accurate representation of the coastline and surrounding waters. A nautical chart shows coastlines, islands, shoals, soundings, isolated dangers, buoys, lights, leading lines, restricted areas and the main landmarks used for navigation.

For an offshore licence candidate, the chart is used to carry out navigation and calculation exercises. It allows the student to work with a departure position, an arrival position, a course, a distance and, depending on the exercise, information relating to current and navigation by dead reckoning.

The nautical chart therefore becomes an important training tool. It provides a practical way of applying theoretical concepts such as latitude, longitude, bearing, true course and estimated position.

Reading a Nautical Chart for the Offshore Licence

Reading a nautical chart begins by identifying its scale and geographical coverage. A chart designed for detailed coastal navigation does not provide the same level of information as a chart covering a large section of the Atlantic Ocean.

Candidates must learn to identify the main cartographic features:

• meridians and parallels;

• latitude and longitude;

• soundings and depth contours;

• depths according to the chart's reference system;

• navigational hazards;

• buoys and other navigation marks;

• lights and their characteristics;

• landmarks and conspicuous objects;

• ports, anchorages and channels;

• restricted or regulated areas;

• specific limits and navigational information.

Understanding chart symbols and abbreviations is essential. A nautical chart is not read like a road map or tourist map: every symbol has a specific navigational meaning.

Latitude, Longitude and the Vessel's Position

Latitude and longitude form the basis of maritime positioning. The offshore boating licence requires an understanding of how a geographical position is expressed and how it can be plotted on a chart.

Latitude is the angular distance north or south of the Equator. Longitude is the angular distance east or west of the prime meridian. On a nautical chart, these coordinates make it possible to determine the vessel's position accurately.

Exercises may also involve determining an estimated position. The navigator must then be able to calculate the theoretical position of the vessel according to its course, speed and elapsed time, while taking the effects of current and leeway into account where necessary.

This method remains important in real-world navigation, particularly for checking the consistency of information provided by a GPS or electronic navigation system.

Plotting a Course on a Nautical Chart

Plotting a course means determining the route that a vessel should follow between two positions. On the chart, the navigator can draw the intended track and determine its direction.

The work may involve true course, heading to steer, bearings and distances. A nautical chart immediately shows obstacles and hazards that may lie along the planned route.

In an offshore licence exercise, for example, the candidate may have to determine a route between two points off Brittany, in the English Channel or in the Mediterranean. The candidate must then correctly use the chart graduations and navigation instruments.

Accurate plotting is important. A reading or plotting error can result in a significant difference on a route covering several tens of nautical miles.

Current, Leeway and Dead Reckoning

Offshore navigation does not simply consist of drawing a straight line between two points. A vessel is affected by several factors that can alter its actual track.

Current is particularly important. It can move the vessel sideways in relation to the originally planned route. The navigator must therefore distinguish between the desired direction of travel and the direction in which the vessel actually needs to be steered in order to reach the destination.

Offshore licence exercises provide an opportunity to understand the difference between course, heading, speed and actual movement. The chart is then used as a graphical tool to visualise the effect of current and determine a corrected course.

Dead reckoning complements these concepts. Starting from a known position, course and speed, the navigator can estimate the position reached after a given period of time. This estimated position can then be compared with available information in order to monitor the navigation.

Distances and Chart Scale

Measuring distances is a fundamental skill for the offshore boating licence. On a Mercator nautical chart, distances are measured using the latitude scale.

The navigator generally uses dividers to transfer a distance between two points and compare it with the latitude graduations. This method allows the distance to be determined in nautical miles.

Mastering this technique is essential for calculating the duration of a passage, estimating an arrival time or checking the consistency of a navigation exercise.

It also helps explain the differences between coastal and offshore navigation. The greater the distance travelled, the more important it becomes to identify and correct navigational errors.

SHOM Nautical Charts for Navigation

SHOM charts are a major reference for navigation around the French coastline. They cover the English Channel, the Iroise Sea, Brittany, the Bay of Biscay, the French Atlantic coast and the French Mediterranean coast.

Depending on the area and intended use, the navigator may require a paper chart at an appropriate scale. A detailed chart is particularly useful for coastal approaches, harbour entrances and areas containing numerous navigational hazards.

SHOM also publishes digital products and different types of cartographic documents intended for specific uses. For offshore licence training, the main objective is to understand the principles of chart reading, positioning, measurement and plotting.

The English Channel, Atlantic and Mediterranean

Navigation exercises can cover different French maritime areas.

In the English Channel, chartwork can include areas around ports such as Cherbourg, Le Havre, Dieppe, Saint-Malo and Brest, in an environment characterised by tides, currents and numerous coastal hazards.

Along the Atlantic coast, areas around La Rochelle, Lorient, Saint-Nazaire, Bordeaux or Bayonne provide different configurations, with extensive sea areas and sometimes complex harbour approaches.

In the Mediterranean, charts may cover Marseille, Toulon, Nice, Cannes, Ajaccio or Bastia. Navigation conditions differ, particularly because tidal ranges are limited in many areas and weather conditions can change rapidly.

For international navigation, publishers such as Admiralty, Imray and NV Charts also provide charts covering the English Channel, North Sea, Atlantic Ocean, Mediterranean Sea, Caribbean and many other European and international sailing areas.

Paper Charts and Electronic Navigation

The paper chart retains an important role in navigation training. It allows the navigator to view an entire maritime area, plot a route and perform calculations directly on the chart.

Electronic charting provides additional capabilities, including real-time GPS positioning, zoom functions, dynamic route display, additional information and data overlays.

These two approaches are complementary. An offshore navigator needs to understand the fundamental principles of navigation independently of electronic equipment. In the event of a power failure, equipment problem or electronic malfunction, the ability to use a paper chart and traditional navigation instruments provides an additional level of safety.

Navigation Instruments Required for Chartwork

The nautical chart is generally used with several simple and precise instruments:

• dividers for measuring and transferring distances;

• a ruler or navigation protractor;

• a Cras navigation plotter for plotting courses and determining directions;

• a sufficiently fine pencil for accurate plotting;

• an eraser for correcting chartwork;

• a calculator for exercises requiring numerical calculations.

Good-quality, accurate instruments make chartwork considerably easier. For the offshore licence, it is useful to practise regularly with the same instruments that will be used during navigation exercises.

How to Choose a Nautical Chart for the Offshore Licence

The choice of chart mainly depends on the geographical area and the training objective. To learn navigation calculations, it is preferable to use a chart that is sufficiently clear and has easily identifiable graduations.

You should also check:

• the geographical area covered;

• the chart scale;

• the level of detail;

• the edition and available updates;

• whether the chart is paper or digital;

• the readability of soundings and symbols;

• its suitability for the exercises being studied.

A chart intended for offshore licence training should make it easy to work with positions, courses, distances and the various navigation calculations.

From Licence Training to Real Navigation

The nautical chart used during offshore licence training should not be considered merely as an examination aid. The methods learned are directly related to real navigation.

Knowing how to plot a position, measure a distance, determine a course, assess hazards and anticipate the effects of current provides a solid foundation for planning a passage.

These skills become particularly important as the vessel moves farther from the coast. Beyond 6 nautical miles from a shelter, French regulations distinguish different navigation areas for the purposes of determining the safety equipment required on board.

The nautical chart therefore remains a tool for planning, monitoring and safety, even when the vessel is equipped with modern electronic navigation systems.

Conclusion

A nautical chart for the French offshore boating licence is an essential tool for learning the fundamentals of offshore navigation. It provides a practical way to understand latitude and longitude, determine a position, measure a distance, plot a course, calculate a heading and take current and leeway into account.

SHOM nautical charts are particularly suitable for studying navigation around the French coastline, while Admiralty, Imray and NV Charts provide extensive coverage of international sailing areas.

Mastering the paper chart is above all a lasting navigation skill. It enables sailors to maintain an independent representation of their route and to check the information provided by electronic navigation systems.

FAQ – Nautical Chart for the French Offshore Boating Licence

Which nautical chart should I use to prepare for the French offshore boating licence?

You need a nautical chart that is sufficiently detailed and clear to carry out exercises involving position fixing, course plotting, distance measurement, heading and dead reckoning. The choice depends mainly on the geographical area and the type of exercise.

Do I need to know how to read a nautical chart for the offshore licence?

Yes. Reading and using a nautical chart are fundamental skills when preparing for the French offshore boating licence extension.

What is the difference between the coastal option and the offshore extension?

The coastal option allows navigation at sea up to 6 nautical miles from a shelter. The offshore extension allows navigation at sea without a distance limit.

Do I need to know how to use a Cras navigation plotter for the offshore licence?

The Cras navigation plotter is a traditional navigation instrument particularly useful for plotting a course and determining a direction on a nautical chart. It provides a practical way to practise traditional chartwork techniques.

Do I still need to learn paper-chart navigation if I have a GPS?

Yes. GPS and chartplotters make navigation considerably easier, but understanding paper-chart navigation allows you to check a route and retain an independent navigation method in the event of an electronic equipment failure.

Are SHOM charts suitable for offshore licence training?

SHOM charts are particularly suitable for studying navigation around the French coastline. Their content allows students to work with soundings, navigational hazards, aids to navigation and the various cartographic features used in maritime navigation.

Can a nautical chart used for licence training also be used for real navigation?

Yes. The skills acquired during offshore licence training can be directly applied to coastal and offshore passage planning, alongside the appropriate nautical publications and electronic navigation systems.