How Pirates of Old Navigate the Sea
Modern cargo ships contain radar, communication tools, global positioning systems, and accurate maps, called charts, that allow them to navigate the seas easily. Ship navigators can even use some of these tools to study weather patterns and avoid dangerous storms that may be looming ahead. Pirates, unfortunately, had none of these high-tech gadgets to assist them in sailing the seas.
Maps and Passages
Pirates usually attacked merchant ships that were sailing commonly-used shipping lanes. The routes were known, and the pirates would just lie in wait until a trade ship sailed by. Many pirates moved from place to place, so they had to have some knowledge of navigation and make sound decisions, or they would end lost at sea.
The conquistadors of Spain sailed and charted most of the lands in the New World during the 16th century. Mapmakers, called cartographers, constructed detailed maps of land masses and seas that their ships explored. The captains of the Spanish galleons and other merchant ships used these maps to assist them in sailing from one port to another.
The pirates were not as organized as the Spanish government, so they didn't have an organized system for making and sharing maps. Pirates were, however, very good at stealing what they needed.
Detailed charts stolen from captured ships enabled pirates to explore unknown waters and coastlines. These maps also provided pirates with information about the routes that merchant ships traveled, enabling them to plan future attacks.
The conquistadors of Spain sailed and charted most of the lands in the New World during the 16th century. Mapmakers, called cartographers, constructed detailed maps of land masses and seas that their ships explored. The captains of the Spanish galleons and other merchant ships used these maps to assist them in sailing from one port to another.
The pirates were not as organized as the Spanish government, so they didn't have an organized system for making and sharing maps. Pirates were, however, very good at stealing what they needed.
Detailed charts stolen from captured ships enabled pirates to explore unknown waters and coastlines. These maps also provided pirates with information about the routes that merchant ships traveled, enabling them to plan future attacks.
Navigational Aids
Although maps were difficult to come by, pirates did have access to common navigational instruments that were used to find the right direction when sailing the seas without land as a guide. Detailed charts were extremely important to pirates, as they helped determine an approximate fixed position in the sea.
Navigational instruments were used to help pirates locate their position on a map. Many maps and charts had lines of latitude and longitude. Knowing the latitude helped pirates calculate their north/south position and the longitude signaled their east/west position.
Using some of the navigational instruments on these pages, pirate navigators would take regular readings and plot the position of the ship on a map, enabling them to determine their location and distance traveled. These instruments weren't totally accurate and reliable, but they did give the ship's captain a good idea of where the ship was going.
Pirates may have also used telescopes to sight land and wind vanes to determine wind direction. The compass was probably the most important navigational instrument on the ship. It was used to determine the basic cardinal directions of north, south, east, and west.
A compass has a small, floating needle that is magnetized on one side, indicated by an arrow. This magnetized arrow is drawn to a magnetic field near the North Pole, so it always points north. Determining east/west position was most problematic for the pirates. They used an astrolabe to determine the ship's latitude.
A pirate navigator would take two readings while looking through two small holes in the moving pointer of the astrolabe. First, the navigator calculated the height of the sun at noon. Second, he calculated the height of the North Star at night. The sun and the North Star (called Polaris) were fixed positions.
Navigational instruments were used to help pirates locate their position on a map. Many maps and charts had lines of latitude and longitude. Knowing the latitude helped pirates calculate their north/south position and the longitude signaled their east/west position.
Using some of the navigational instruments on these pages, pirate navigators would take regular readings and plot the position of the ship on a map, enabling them to determine their location and distance traveled. These instruments weren't totally accurate and reliable, but they did give the ship's captain a good idea of where the ship was going.
Pirates may have also used telescopes to sight land and wind vanes to determine wind direction. The compass was probably the most important navigational instrument on the ship. It was used to determine the basic cardinal directions of north, south, east, and west.
A compass has a small, floating needle that is magnetized on one side, indicated by an arrow. This magnetized arrow is drawn to a magnetic field near the North Pole, so it always points north. Determining east/west position was most problematic for the pirates. They used an astrolabe to determine the ship's latitude.
A pirate navigator would take two readings while looking through two small holes in the moving pointer of the astrolabe. First, the navigator calculated the height of the sun at noon. Second, he calculated the height of the North Star at night. The sun and the North Star (called Polaris) were fixed positions.
Navigators knew that the further north they sailed, the higher the North Star would appear in the sky. It would appear lower on the horizon the further south they sailed. By taking these readings and calculating the angle between their ship and the sun or North Star, pirates could determine their approximate north/south position.
The main problem with the astrolabe was that it could only be used when the skies were clear so the navigator could see the sun or North Star. Also, if the pirate ship was sailing in the southern hemisphere, the navigator would have to rely on the sun, because the North Star could not be seen at night.
The cross-staff was one of the earliest navigational instruments used to determine latitude. Like the astrolabe and the compass, this tool was difficult to use on rough seas, as it required a steady hand to produce an accurate reading.
The cross-staff was a long staff, longer than a yard stick, which was held on the shoulder and pointed at the sun. On the staff were several cross-bars of different sizes, which pointed up and down when held to the sky.
The navigator would choose the cross-bar that closely matched the distance between the fixed position, like the sun, and the ocean. By sliding the selected cross-bar back and forth until it touched both the fixed body and the horizon, the navigator could convert the reading on the cross-staff to the approximate latitude.
Dead reckoning was a complicated process of determining how far a ship had traveled based on its speed. First, navigators would determine their north/south direction. The winds did not always move in the same direction as the ship, so the ship had to turn back and forth to use the wind to its advantage, allowing it to sail back and forth to achieve the desired direction. This was called tacking.
Second, to calculate the speed of the ship, pirates may have tied a small log to a rope with a series of knots in it. When tossed overboard, the navigator would count how many knots passed the hand against a minute hourglass to calculate the approximate speed of the ship.
The main problem with the astrolabe was that it could only be used when the skies were clear so the navigator could see the sun or North Star. Also, if the pirate ship was sailing in the southern hemisphere, the navigator would have to rely on the sun, because the North Star could not be seen at night.
The cross-staff was one of the earliest navigational instruments used to determine latitude. Like the astrolabe and the compass, this tool was difficult to use on rough seas, as it required a steady hand to produce an accurate reading.
The cross-staff was a long staff, longer than a yard stick, which was held on the shoulder and pointed at the sun. On the staff were several cross-bars of different sizes, which pointed up and down when held to the sky.
The navigator would choose the cross-bar that closely matched the distance between the fixed position, like the sun, and the ocean. By sliding the selected cross-bar back and forth until it touched both the fixed body and the horizon, the navigator could convert the reading on the cross-staff to the approximate latitude.
Dead reckoning was a complicated process of determining how far a ship had traveled based on its speed. First, navigators would determine their north/south direction. The winds did not always move in the same direction as the ship, so the ship had to turn back and forth to use the wind to its advantage, allowing it to sail back and forth to achieve the desired direction. This was called tacking.
Second, to calculate the speed of the ship, pirates may have tied a small log to a rope with a series of knots in it. When tossed overboard, the navigator would count how many knots passed the hand against a minute hourglass to calculate the approximate speed of the ship.