Improvements in Shipbuilding and Navigation

Technological advances in shipbuilding and navigation provided mariners of the Middle Ages the means for safer and swifter sea journeys and led to increased cultural, intellectual, and religious integration, as well as economic and military expansion and colonialism throughout the Eastern Hemisphere.

Summary of Event

It is desirable to view the achievements of medieval maritime technology under two broad headings: the actual design and construction of sailing vessels themselves and medieval methods of navigation, including their purpose and application. [kw]Improvements in Shipbuilding and Navigation (c. 1250)
[kw]Shipbuilding and Navigation, Improvements in (c. 1250)
[kw]Navigation, Improvements in Shipbuilding and (c. 1250)
Travel by sea
Europe (general);c. 1250: Improvements in Shipbuilding and Navigation[2420]
Middle East;c. 1250: Improvements in Shipbuilding and Navigation[2420]
Engineering;c. 1250: Improvements in Shipbuilding and Navigation[2420]
Science and technology;c. 1250: Improvements in Shipbuilding and Navigation[2420]
Trade and commerce;c. 1250: Improvements in Shipbuilding and Navigation[2420]
Transportation;c. 1250: Improvements in Shipbuilding and Navigation[2420]
Neckam, Alexander
Lull, Raymond

The construction of vessels both for commerce and for warfare underwent significant development during the high Middle Ages, with Byzantines, Arabs, Italians, and Norsemen all contributing to the process. Greek Byzantine ship designers contributed the dromond, the classic light navy cruiser for home defense and the suppression of piracy in the eastern Mediterranean.

This relatively long ship with reasonable beam was swift and maneuverable, rugged and deadly in ship-to-ship encounters. The dromond was provided with a type of armor plating, a devastating battering ram, positions for archers, and a series of heavy catapults for throwing missiles containing the dreaded Greek fire. It is reported that some shipboard catapults could throw a half-ton weight almost half a mile, thus making the older Roman technique of boarding the opponent obsolete. These admirable ships were propelled either by banks of oars or by lateen sails, triangular sails held to a mast amidships.

Though they were seldom naval adventurers, the Arabs, too, contributed to the art of ship construction during the Middle Ages. In sheer size, the Moorish crafts were exceptional, sometimes attaining a payload of more than three hundred tons. Never venturing far from shore, these Arabic ships were supremely handy underway and could dart to shelter whenever threatened by a superior force. Muslim shipbuilders also introduced to the Western world the practice of building roomy and comfortable cabins aft for captain, officers, and supernumeraries. They depended heavily on oar propulsion.

When sails were added, they were generally carried on two masts, the forward one holding a small sail, while the midship mast carried the far larger mainsail.

The famous “long ships” of the Vikings Vikings excite both historical and aesthetic interest, for many of their actual remains were unearthed in the twentieth century. The Norse vessels are widely regarded as among the most perfect that have ever been designed and executed. Capable of withstanding the rigors of their icy home waters, these long ships with graceful lines, high freeboards, and relatively narrow beams, the ends rising high and menacing, were equally ready to meet the Atlantic swells. Skillfully constructed, the sides were built of long strakes, overlapped one above the other to provide additional rigidity. At the same time, the strakes were warped and curved, to “build in” a natural tension, thus obtaining a “royal” sheer and additional strength. Though wide amidships, the Viking hull tapered neatly to a point at each end, for exceptional maneuverability. Though generally worked with banked oars, the Viking ships could also mount considerable canvas and were probably able to beat into the wind. Finally, the Vikings pioneered the use of the rigid long keel, around which the sides of the ship could curve and swirl, supported by the strength of the ship’s stout backbone.

The inventive Venetians Venice;shipmaking led the Mediterranean in the sheer numbers of vessels they produced and maintained. The famed “Serenissima” perhaps employed Europe’s first assembly line, a waterborne factory that in one day could turn out a finished and equipped galley. The main subassemblies of each galley were completed in separate warehouses and then brought together in sequence along one of Venice’s many canals.

In form, the Venetian galley resembled an elongated and flattened Roman trireme, with an added apostis or overhanging main deck somewhat similar to that of a modern aircraft carrier. As in most medieval vessels, oars provided the prime motive power. They were arranged on the gunwales generally in groups of three, with three rowers working from each rowing bench. When employing sails, especially for long voyages, a huge lateen rig, often square, was hung from a single mast amidships. A box at the top of the mast housed the wheels and gears necessary to raise and lower this large area of canvas. The rigging had no permanent yards or stays, sheaves, or blocks; when the ship changed direction the whole rig had to be cast off to leeward. If a radical change of weather were encountered, the whole sail, tackle and all, was exchanged for one of different configuration or size.

Medieval mariners made great advances in handling their vessels. Most medieval craft were equipped with adequate rudders, or in the case of the Vikings with outsized steering oars mounted starboard. Their bite or penetration in the water was deeper, assisting in steering a straighter course and beating farther to windward when necessary. One of the significant advances was learning how to tack, or sail a zigzag course utilizing wind pressure not directly astern. Some could sail with the wind abeam and some even with the wind quartering on the bow, no mean achievement without highly developed standing rigging.

Sailing farther from land on longer voyages, medieval mariners needed reliable instruments to assist them in plotting their courses and positions. Early Egyptians and their Phoenician inheritors probably navigated at first simply by the position of the sun, keeping it on one hand or the other in order to determine their approximate direction of travel. If the Greek historians are correct, the ancient Greeks also sailed by the sun and did not sail at night. The Romans, copiers of older cultures in this case, made few navigational improvements, preferring to leave seafaring to other peoples when possible.

A Venetian galley off the Dalmatian coast. Marco Polo is supposed to have traveled in such a ship.

(F. R. Niglutsch)

During the Middle Ages, however, the compass, the astrolabe, and the nocturnal each aided the sailor in finding either his direction or his latitudinal position. The invention of the compass has been claimed by many countries. Although probably of Asian origin, it is claimed to have been invented by the Finns, the Norsemen, and the Arabs. The use of a magnetized bar or needle is first mentioned in Western medieval texts around 1200 in the works of Alexander Neckam Neckam, Alexander and Guy of Provins Guy of Provins . Probably the principle of the lodestone always pointing north had long been known and utilized for centuries in Europe, but the high Middle Ages witnessed significant refinements in the art of compass Compass construction and utilization such as the development of the compass card, or compass “rose,” which marked the cardinal directional points. Early compasses probably were nothing more than needlelike pieces of soft iron inserted into a straw and later mounted on a wooden float. Medieval mariners skillfully compensated for “needle dip” and the vexatious deviation to which magnetic compasses are prone when near ferrous metals by inscribing special lines upon compass cards.

The astrolabe Astrolabe , ancestor of the common sextant, was the second important navigational aid available to medieval seamen. In essence the astrolabe is a device for measuring latitude, or one’s position north or south of the equator. The astrolabe was a portable tool, though it generally required three men with steady hands to operate it: one to hold it, one to take the sights, and the third to read the attached scales. The instrument itself was a circle constructed of a heavy material to make it easier to hold. In the center of the circle was a pin with a pointer pivoting about it, a pointer with its center line carefully marked. One end of the pointer was aimed at a heavenly body, generally the sun or the North Star. The observer placed his eye at the opposite end of the pointer and aligned the two ends upon the observed object. When this was done and the astrolabe was hanging exactly plumb, the altitude could be read on the attached scale. From the observation of the altitude of a known celestial object, it was possible to calculate approximately the latitude of the observing vessel. The astrolabe was not easy to use, however, for even in a moderate sea, it was difficult to hold it steady, and when sighting the sun, troublesome shadows could confuse the observer.

A third medieval navigational instrument, less well known than the compass or the astrolabe, was the nocturnal Nocturnal , possibly the invention of Raymond Lull Lull, Raymond of Mallorca. The nocturnal was also used to establish latitude, using the North Star as guide. Looking like a circular slide rule, the nocturnal consisted of three discs, containing respectively hours, dates, and the figure of a man, all pinned together, with a hole in the center. The object was held at arm’s length, and the observer sighted the North Star through the center hole. The disc with the figure of the man on it was then rotated until his head lined up with the “pointer” star Kochab in the Big Dipper. The observer could than read the correction to be added or subtracted from the altitude of Polaris and arrive at latitude. One could also read the time of nigh from the third disc.


The advent of better ships and better navigational tools marked a new era in exploration and expansion throughout the Eastern Hemisphere, including increased interregional trade, the exchange of scientific and cultural ideas, religious conversions, military conquest, and the slave trade, especially out of Africa.

Where previously mariners navigated primarily using the sun and stars, technology such as the compass, the astrolabe, and the nocturnal, and precision ship design that took advantage of the strong and perpetual winds of the sea, increased the effects of maritime exploration on the known world.

Further Reading

  • Aczel, Amir D. The Riddle of the Compass: The Invention That Changed the World. New York: Harcourt, 2001. A brief but detailed and thorough account of the invention of the compass. Also discusses the history of navigation to the fifteenth century
  • Calahan, Harold Augustin. The Sky and the Sailor. New York: Harper and Row, 1952. An account of the development of the art of navigation from the dawn of the astronomical art to the twentieth century.
  • Coggins, Jack. By Star and Compass: The Story of Navigation. New York: Dodd, Mead, 1967. A history of navigation featuring prolific maps and illustrations by the author.
  • Collinder, Per. A History of Marine Navigation. Translated by Maurice Michael. New York: St. Martin’s Press, 1955. A study of the techniques and the mechanisms by which humans have navigated upon the sea since the time of the Phoenicians. It investigates the trade winds and the monsoons, the origin and development of the compass and the astrolabe, the beginnings of map making, and the problems of spherical projection.
  • Gardiner, Robert, and Arne Emil Cristensen, eds. The Earliest Ships: The Evolution of Boats into Ships. Reprint. Edison, N.J.: Chartwell Books, 2001. A comprehensive history of seafaring technology from antiquity through the Middle Ages.
  • Hewson, J. B. A History of the Practice of Navigation. 2d ed. Glasgow: Brown, Son and Ferguson, 1983. A useful and readable introduction to the instruments of navigation and their application.
  • Jobe, Joseph, ad. The Great Age of Sail. Translated by Michael Kelly. Lausanne, Switzerland: Edita Lausanne, 1967. A folio-sized volume illustrating in detail the five great centuries of the European sailing vessel.
  • McGrail, Sean. Boats of the World: From the Stone Age to Medieval Times. New York: Oxford University Press, 2002. Organized by region, covers the history of maritime travel and shipbuilding on every continent.
  • Taylor, Eva Germaine R. The Haven-Finding Art: A History of Navigation from Odysseus to Captain Cook. New ed. London: Hollis and Carter, for the Institute of Navigation, 1971. An up-to-date account of navigation “from Odysseus to Captain Cook.”
  • Varende, Jean de la. Cherish the Sea. Translated by Mervyn Savill. New York: Viking Press, 1956. One of the best books available for the study of medieval ship design The author discusses technical subjects that are lightened with illustrative anecdotes. Terms and concepts are simplified and abstruse mathematical formulas are avoided when dealing with problems of practical navigation.
  • Whall, W. B. Rovers of the Deep. New York: Robert M. McBride, 1953. A work of particular interest dealing with the early Atlantic voyages of exploration after the time of Prince Henry the Navigator.