Setting out to navigate is no simple task. However, there are certain tools and instruments that, when used correctly, make navigation easier and turn it into a pleasant and safe experience. This is the case with the nautical chart, which plays a key role by providing essential information for sailors.
Do you know all its types and how to read it? Don’t worry — at Motyvel, we explain how to do it so you can enjoy a safe, trouble-free adventure.
What is a nautical chart?
Imagine a nautical chart as a much more detailed map of the marine environment, providing sailors with critical information to avoid hazards and calculate routes. Its particular feature is that these charts, besides representing the water’s surface, detail what lies beneath, such as depths and underwater obstructions, and help identify dangerous areas or zones that are difficult to navigate. They are used in seas, oceans, rivers, lakes, and any navigable body of water to ensure a safe journey.
In other words, a nautical chart is a cartographic document designed with a high degree of precision, whose main purpose is to provide detailed information about the marine environment and potential hazards to navigation. But what information is included? Details such as water depths, the location of lighthouses, buoys, currents, tides and other navigational aids. Furthermore, nautical charts are updated regularly to reflect changes in maritime conditions and coastal infrastructure, making them indispensable tools for captains, fishermen, marine scientists, and recreational sailors.
What is their purpose?
The primary purpose of a nautical chart is to represent the maritime environment accurately and in detail to provide a clear and complete view of navigable areas. For this reason, they allow sailors to perform the following functions:
- Orient themselves correctly, as they know at all times where they are and where they are heading.
- Avoid hazards both underwater and on the surface, such as sandbanks, submerged rocks, reefs, or restricted areas.
- Determine water depth to know whether it is safe to continue or if there is a risk of running aground.
- Identify navigational aids such as lighthouses, buoys, and beacons, which guide ships along safe routes and warn them of dangerous zones.
- Plan routes and measure distances accurately to reach their destination in the safest way possible.
But these are not their only functions. Nautical charts also provide information on ocean currents, tides, and other maritime conditions that may affect a vessel’s course.
Types of nautical charts
Nautical charts are adapted to different needs and navigation scenarios. Depending on the area and level of detail required, several types of nautical charts exist:
Coastal charts
These are designed for near-shore navigation, where details about ports, bays, beaches, and coastal obstacles are essential for sailors. They are generally used by small fishing or recreational vessels, as well as commercial ships that need to perform precise manoeuvres when approaching land.
Ocean charts
These are mainly used for open-sea navigation. Although they do not offer the same level of detail as coastal charts, they are useful for plotting long routes between continents or across open waters. They provide general information on ocean currents, areas of extreme depths, and some distant coastal reference points.
Harbour charts
These charts are extremely detailed and designed to make entering and leaving harbours, channels, or bays easier. They include information on docks, access channels, depths at berthing points, and any obstacle or restriction for safe manoeuvring within a port.
Special charts
Certain navigation areas may require specific manoeuvres or techniques. For this reason, special charts exist for navigating rivers or lakes, ice areas, or charts highlighting areas of interest for scientific research.
What instruments do I need to read a nautical chart?
To interpret and use a nautical chart correctly, it is essential to have a set of key instruments that help measure distances, plot courses, and determine positions:
Navigational compass
This instrument is used to measure distances on the nautical chart and transfer them to a scale. It consists of two legs that can be adjusted to measure the distance between two points on the chart and then compare it with its scale. It is also useful for drawing equal-distance circles, such as marking lighthouse or buoy coverage areas.
Parallel ruler
The parallel ruler is an indispensable tool for plotting courses and straight lines. It consists of two rulers connected by a mechanism that allows them to move in parallel, making it possible to transfer a line on the chart without altering its original angle.
Nautical protractor
Its main function is to measure angles and determine courses on the chart. It is usually semicircular or circular in shape, with a degree-graduated scale. It allows you to measure the angle of a course with respect to north, whether magnetic or true.
How to read a nautical chart
To correctly use a nautical chart during navigation, we must follow a series of steps to interpret the information accurately:
1. Identifying the current location and destination
First, we must determine the vessel’s current position on the nautical chart. This can be done through different methods, such as using a GPS or visual references like lighthouses, buoys, or recognisable geographical features.
2. Determining the course and calculating distances
Next, the course to follow is plotted. Using a parallel ruler or nautical protractor, a straight line is drawn between the starting point and the destination. This is the base course the vessel must follow. Then, the angle of this course with respect to north (magnetic or true) is measured to determine the exact degrees of the required heading. Finally, this measurement is compared with the chart’s scale to obtain the real distance in nautical miles. Thanks to this calculation, we can estimate the travel time to reach the destination.
3. Identifying hazards or reference points along the route
With the course and distance defined, the next step is to identify any potential hazards or reference points along the route. It is important to examine the chart to locate hazards such as submerged rocks, sandbanks, reefs, restricted areas, or dangerous navigation zones. But how can we identify them? They are represented by specific symbols and colours. Likewise, it is essential to identify lighthouses, buoys, beacons, and islands that serve as guides along the way. In some cases, the chart also provides information on ocean currents or areas with significant tidal ranges, which is important to adjust the course if necessary.
Motyvel: unforgettable experiences
It’s clear that, to ensure well-planned navigation and turn it into a memorable experience, we must have a nautical chart and know how to read it. Through its correct interpretation, we can guarantee calm, hazard-free sailing.
At Motyvel, we are navigation experts and offer rental, sales, winter storage, mooring, and comprehensive services for vessels. Simply tell us when and how you imagine your holiday at sea, and we will take care of the rest. Get in contact with our team so we can help you and make your dream of sailing with total comfort and safety come true.
