Basics of Marine Navigation

Marine Navigation Basics – How to Navigate a Boat

marine navigation basics

Whether your watercraft of choice is a speedboat, yacht, or something in between, knowing the basics of marine navigation is absolutely essential when you’re spending time on the water. Below is Van Isle Marina staff’s quick guide to the basics of navigation. We’ve included some short definitions to go with our roundup of the traditional manual tools that truly experienced sailors swear by, as well as electronic devices with all the bells and whistles.

Navigation buoys

Marine Navigation – Learning Your Directions

Latitude & Longitude – A coordinate system that allows you to pinpoint exactly where you are on Earth, whether on land or at sea. Latitude measures north & south, while longitude measures east & west.

True North – Also known as geodetic north, this marks the position of the geographic North Pole according to the position of the Earth’s axis. Not to be confused with the magnetic North Pole, which shifts by kilometres every year due to moving sea ice, the geographic North Pole is where the lines of longitude converge. The same is true for the South Pole. A sextant can help.

Knots – 1 knot or kn is 1.15 mph or 1.852 km/h, a measure of speed for boats and aircraft.  This unit of measurement has been used since the 17th century, when the speed of ships was measured by a rudimentary device made of coiled rope with evenly spaced knots.

This rope was attached to a pie-shaped piece of wood that floated behind the ship and was let out for a certain amount of time. When the line was pulled back in, the number of knots (roughly the speed of the ship) between the wood and the ship were counted.

Nautical Mile – A nautical mile is equal to one minute of latitude and is based on the Earth’s circumference. One nautical mile equals 1.1508 statute (land measured) miles.

Marine Navigation – Tools Marine Navigation - magnetic compass

Magnetic Compass – Tried and true, and something that every sailor should have on hand since it doesn’t require any electricity to operate. The magnetic compass points to magnetic north and you can read your direction using the needle or the “lubber line.” There are 360 degrees, with 0 degrees to the north, 180 degrees to the south, 90 degrees to the east, and 270 degrees to the west. The direction your boat is heading in measured in degrees relative to magnetic north.

Rules – A set of parallel rulers that determine the angle (degrees) between the starting point and destination. They are attached by swivelling arms that you can “walk” across a nautical chart, while maintaining the correct angle.

Dividers – Used to measure distance on a nautical chart, dividers are used to separate two points on the chart to represent one or many nautical miles.

GPS – Global Positioning System (GPS) devices receive signals from satellites to pinpoint your position, plot your course, and determine speed. They’re increasingly popular among boaters for their simplicity, ranging from very basic to high end, complete with depth alarms and chart plotters, among other extras.

Marine Navigational Aids

marine navigation - buoys

Buoy – An anchored buoy serves as a marker for watercraft. Port hand buoys are green and mark the left side of a passage, or an obstruction in the water. Starboard hand buoys are red and mark the right side of a passage, or an obstruction in the water. A simple rule is to keep green buoys on the left side and red buoys on the right to keep with traffic and avoid hazards. Buoys also come in different shapes and sizes.

Cardinal Marks – There are north, south, east, and west cardinal buoys, which mark the safest direction to travel. These may have a white light on top that each follow a specific pattern, and they’re coloured for easy direction identification:

  • North- Painted black on top, yellow on bottom
  • South- Painted yellow on top, black on bottom
  • East- Painted black on top and bottom, yellow in the middle
  • West- Painted yellow on top and bottom, black in the middle

See complete details on the different types of marks.

Lights – Lights used on buoys for marine navigation are all assigned specific patterns of speed and number of flashes. Cardinal buoys have white lights with a flashing speed and pattern that corresponds to the position on an analog clock. For instance, east buoys flash at a rate of 3 times every 10 seconds.  Special types of buoys, like anchorage buoys and cautionary buoys have a yellow light that flashes once every 4 seconds.

marine navigation - paper charts

Paper Charts – A paper chart is still the most reliable form of charting when on the water and is used to plot courses between point A and point B, determine depth of water, any charted obstructions, navigation aids, and information on currents and tides.

Electronic Charts –  The Electronic Navigational Chart (ENC) uses computer software and databases to provide details for charting when on the water, ENC’s use a dynamic map that shows your location in real time. The most complex are Vector charts, which allow you to filter out any layers of

Marine Navigation - Electronic charts

information you may not need at all times, such as location of buoys, direction of current or depth of water.  This navigational tool can be used on a waterproof chart plotter, smartphone or tablet, and laptop.

Read More: Important Items to Bring on Your Boat


Whether you’re brand new to boating or a seasoned skipper, we at Van Isle Marina believe it never hurts to brush up on the basics to ensure everyone has a great—and safe—time on the water. Rely on our expertise to help you choose the navigation tools and equipment that are right for you, and pick up a cruising guide, chart or tide book, or other supplies for your aquatic adventures at our Dock Store.

Come and see us – we are your Pacific Northwest boating experts!