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Living on a boat: Navigation at Sea

Living on a boat: Navigation at Sea


Today navigation at sea is simple. On your GPS plotter, press the “ON” button and on the map you can immediately see where you are, at what speed and in which direction you are sailing, the cities and marinas nearby, and many other things that may be important for your safe journey. Unfortunately, several ships, boats and yachts end up stranded on the mainland, on the rocks or in shallow waters each year, and therefore navigation is still one of those things that should be learned well, regularly revised and, above all, pacticed in real life situations.

What does modern navigation look like in practice? Most people sail along the coast and in the areas they already know well, so it is enough for them to look at the coast to know where they are. Sailing among islands requires a better knowledge of navigation and use of modern means of navigation. However, if you are going for longer sailing along the coast, offshore or even to some unknown waters, then you must prepare a navigation plan before departure.

Basics of theory and reality at sea

The theory of navigation, which you learned at a boat helmsman course, is the basis for orientation at sea. Each skipper must know how to read nautical charts, determine course and azimuth using a compass and how to draw them on the map and, most importantly, know at any moment where to and in which direction they are sailing. Unfortunately, theory is one thing, and practice is quite another.

If you have ever tried to determine your position on the map using the angle and distance between two objects on the land, now you are surely smiling. Beginners find the speed of the boat, turning the compass rose, drawing on the map, calculating the variation, and many other things rather challenging, leaving them with the results that are not even nearly close to reality. Not to mention navigation at night …

When you look at the land from the sea, everything looks very similar. If the islands are one behind another, they may seem like one island. Many cities are not clearly visible because of trees and other vegetation, and among the best hidden things are the campsites. You know it is surely there, but you can not find it. These are all situations that make navigation difficult and cause a large number of ‘seasonal captains’ to get lost quite close to the coast. Fortunately, there is the GPS, which shows you your exact location, along with all the cities, islands, bays and other things you do not actually see.

Anyway, before you sail, you should take care that on the roof of a slightly larger boats you have the latest nautical maps, the pilot of your area, two triangles, a compass, a divider, a plain graphite pencil and an eraser. And of course, revise the theory from the course for the skipper.

How to sail safely?

Before going to the sea, make a plan where and how you are going. If you have a small boat with no navigation equipment (GPS), stay close to  the shore and check for any possible hazards on the map beforehand (shallow sea, rocks and other hazards). There is a big difference in navigation depending whether you know some area or not. If you navigate every year in the same part of southern Dalmatia, then you already know all the bays on each island, so you will not waste time navigating using maps or a compass.

A completely different thing is navigation in the area where you are sailing for the first time. Not only the course from point A to point B, but also weather conditions, currents, tides, depths in different areas are all very important for safe navigation. Do not leave everything to GPS, but study the area well and check for any possible hazards on maps. In addition to the maps, excellent data sources are local pilots, with detailed description of the coast, ports and other important data. Just in case, you can also check various forums on the Internet, where you can find “local” tips, warnings and instructions that will make your navigation even safer.

White, green and red light

The next important thing in navigation is light. Lighthouses have been a safe way for seafarers for centuries, and crashes are avoided at night by navigation lights. Each vessel is equipped with green, red and white light, so it is very easy at night to determine in which direction it is sailing. Green light marks the starboard (right side) and covers an angle of 112.5 ° from the bow towards the stern, and the port (left side) is marked by the red light. You can remember this by the fact that the red heart is on the left side. The aft is marked with the white light with an angle of 135 ° and in this way you can quickly know in which direction another vesel is sailing, whether it is approaching you or not. Various combinations of lights also mark many other vessels (over 50 meters long, fishing boats, towing other boats and the like), so you need to remember each one of them well.

Lighthouse on the shore is quickly visible, yet quite another story is a lighthouse at the entrance to a marina or a city port. When you are approaching them from the open sea, there are a thousand other lights behind them – from cars, neon advertisements, public lighting, and so on, so you will need a little more time to find your lighthouse in the light pollution. Characteristics of lighthouses are marked on maps, but you must also keep track of notifications for seafarers, as some of them may change. So it is important to have the latest maps, otherwise you might be searching in vain for your lighthouse.

Black marks in the form of a cone or triangle in different combinations have the same function during the day as lights at night. However, as it is much easier to switch on and off the lights than to raise and lower the day markings, vessels often sail all the time with the same raised markings or do not have them at all.

Marks that you might not be used to

Cardinal marks are another thing that is quickly forgotten if you do not see them for a long time. Marks are extremely important, because if you are going to the wrong side by them, you are sure to crash the boat. Posts of cardinal marks are painted with different black and yellow patterns, with different combinations of triangular markings on the top. They indicate on which side of the cardinal mark the danger is (rocks, shallow waters) and on which side of the cardinal mark you should sail. There are not many of them in the Adriatic, but if you sail to the west of Finland without knowing the cardinal marks, you will not sail long.

Compass, GPS, radar, fishfinder, map – which one of them can you trust?

Navigation with GPS is quick and easy, but the position is unfortunately not exactly correct. The error in the position can be up to 7 meters, making navigation in the open sea perfectly OK, but when docking or similar maneuvers in the marina it is better to use your own eyes, and not just look at the plotter’s screen.

If you get caught in the fog at sea, do not forget the sound signals, and for the safe navigation instead of GPS, it is better to use the radar (if you have one). In combination with maps, it will show you a safe route and other vessels that you can not see due to the fog. Modern navigation plotters can use the same maps for displaying GPS positions and radar images, and then it can be clearly seen how different signals give different positions.

One of the important questions at sea is: “Is it deep enough?” You can look for the answer in many ways. Depths are indicated on maps, depth is shown by a depthometer, some people use “fishfinder”, and yet another option is to place on the bow of a crew member to look into the water and check the depth. In sailboats, it is important to know whether the depth sounder reads the depth under the hull or under the keel, and apart from the depths, height of a bridge above a channel is also important for sailboats.

Compass. If you choose to navigate by  the compass, first turn the vessel to the selected course and find a spot in the distance, according to which the course is kept, and then navigate to it. When planning a journey by the compass, draw a course on the map, make checkpoints, and then regularly monitor if you are on the right track. If the island that by the map should be on your left, appears on your right side, then something is wrong …

How to become a good navigator?

Navigation consists of the knowledge of theory, the right means of navigation (maps, electronic systems and the like) and a lot of practical exercise. Navigation by day is not the same as navigating in fog, at night or in adverse weather conditions, so practice is therefore necessary to gain experience and confidence in your navigational skills.


If you want to become a good navigator, here are some tips:

  • Learn to read maps and remember all important marks first.
  • Learn to recognize cardinal marks, lights, and day signs.
  • Compare what you see on the map with what you actually see from your boat (towns, bays, large buildings, etc.).
  • Try to do one of the exercises to determine your position in navigation and to check the accuracy of your result on GPS.
  • Try to determine the speed of your boat by throwing an object into the sea on the bow and tracking the time in which it passes the stern (for that you must know the length of your boat and should not sail too fast).
  • Whenever you are on board, try to determine the north by sun in different parts of the day (morning, noon, afternoon).
  • Try to determine the distance from the mainland and check it using GPS.
  • Observe lights at the sea, look for different boats, determine their direction of navigation.
  • Check if you can locate a lighthouse on the map (and vice versa) according to the characteristics of the lighthouse flashlights.
  • Sail at night, turn towards an illuminated city and look for lighthouse light or other vessels that sail in front of the city.
  • If you have a GPS plotter, take one afternoon and read user manual to learn as much as you can about the features and capabilities that it provides. Believe me, your position is not everything you can use it for.
  • Try to program your route to the GPS plotter and then follow the route. On longer routes, navigate exactly as planned, not “by heart“ (although you know where and how you need to sail).
  • Get pilots for the area where you most often sail or where you intend to sail.
  • Before going to an unknown area, get informed of the weather conditions, currents, possible dangers, and other specific local information (pilot, map, internet …).

Remember, it takes a lot of practical experience and navigation in different conditions to become a good navigator. Start slowly and in the area you know well, use compass, maps and GPS, and then plan longer and more demanding routes. And do not worry, even Columbus went to India one day and ended up in America.

Text: Matej Ogorevc

Foto: Freepik, Depositphotos



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