Viking ships were marine vessels of unique structure, used in Scandinavia from the Viking Age throughout the Middle Ages. The boat-types were quite varied, depending on what the ship was intended for, [1] but they were generally characterized as being slender and flexible boats, with symmetrical ends with true keel. They were clinker built, which is the overlapping of planks riveted together. Some might have had a dragon's head or other circular object protruding from the bow and stern for design, although this is only inferred from historical sources. Viking ships were used both for military purposes and for long-distance trade, exploration and colonization. [2]
In the literature, Viking ships are usually seen divided into two broad categories: merchant ships and warships, the latter resembling narrow "war canoes" with less load capacity, but higher speed. However, these categories are overlapping; some transport ships would also form part of war fleets. As a rule, ship lanes in Scandinavia followed coastal waters, hence a majority of vessels were of a lighter design, while a few types, such as the knarr , could navigate the open ocean. The Viking ships ranged from the Baltic Sea to far from the Scandinavian homelands, to Iceland, the Faroe Islands, Greenland, Newfoundland, the Mediterranean, the Black Sea and Africa. [3]
The ship's shallow draft allowed navigation in waters only one meter deep and permitted beach landings, while its light weight enabled it to be carried over portages.
The ship has been functioning as the centerpiece of Scandinavian culture for millennia, serving both pragmatic and religious purposes, and its importance was already deeply rooted in the Scandinavian culture when the Viking Age began. Scandinavia is a region with relatively high inland mountain ranges, dense forests and easy access to the sea with many natural ports. Consequently, trade routes were primarily operated via shipping, as inland travel was both more hazardous and cumbersome. Many stone engravings from the Nordic Stone Age and in particular the Nordic Bronze Age, depict ships in various situations and valuable ships were sacrificed as part of ceremonial votive offerings since at least the Nordic Iron Age, as evidenced by the Hjortspring and Nydam boats.
The Viking Age saw the first local developments of trading ports into forts and coastal towns, all of which were deeply dependent on the North Sea and the Baltic Sea for survival and growth. Control of the waterways was of great economical and political importance, and consequently, ships were in high demand. Because of their overwhelming importance, ships became a mainstay of the Viking religion, as they evolved into symbols of power and prowess. The Hedeby coins, among the earliest known Danish currency, have impressions of ships as emblems, showing the importance of naval vessels in the area. [4] Through such cultural and practical significance, the Viking ship progressed into the most powerful, advanced naval vessel in Viking Age Europe.
Knarr is the Norse term for ships that were built for cargo transport. A length of about 54 feet (16 m) and a beam of 15 feet (4.6 m) are not untypical, and the hull could be capable of carrying up to 24 tons. [5] Overall displacement: 50 tons. This is shorter than the Gokstad type of longships, but knarrs are sturdier by design and they depended mostly on sail-power, only putting oars to use as auxiliaries if there was no wind on the open water. Because of this, the knarr was used for longer voyages, ocean-going transports and more hazardous trips than the Gokstad type. It was capable of sailing 75 miles (121 km) in one day, and held a crew of about 20–30. Knarrs [6] routinely crossed the North Atlantic in the Viking Age, carrying livestock and goods to and from Greenland and the North Atlantic islands. The design of the knarr later influenced the design of the cog, used in the Baltic Sea by the Hanseatic League. Examples of Viking Age knarr are Skuldelev 1, which was excavated in Denmark in 1962 and is believed to be from about 1030 AD, and the Äskekärr ship , which was found in Sweden in 1933 and is believed to be from about 930 AD. [7]
Longships were naval vessels made and used by the Vikings from Scandinavia and Iceland for trade, commerce, exploration, and warfare during the Viking Age. The longship's design evolved over many years, as seen in the Nydam and Kvalsund ships. The character and appearance of these ships have been reflected in Scandinavian boatbuilding traditions until today. The average speed of Viking ships varied from ship to ship but lay in the range of 5 to 10 knots (9 to 19 km/h), and the maximum speed of a longship under favorable conditions was around 15 knots (28 km/h). [8]
The long-ship is as a graceful, long, narrow, light, wooden boat with a shallow draft hull designed for speed. The ship's shallow draft allowed navigation in waters only one meter deep and permitted beach landings, while its light weight enabled it to be carried over portages. Longships were also double-ended, the symmetrical bow and stern allowing the ship to reverse direction quickly without having to turn around. Longships were fitted with oars along almost the entire length of the boat itself. Later versions sported a rectangular sail on a single mast which was used to replace or augment the effort of the rowers, particularly during long journeys.
Longships can be classified into a number of different types, depending on size, construction details, and prestige. The most common way to classify longships is by the number of rowing positions on board. Types ranged from the Karvi, with 13 rowing benches, to the Busse, one of which has been found with an estimated 34 rowing positions.
Longships were the epitome of Scandinavian naval power at the time and were highly valued possessions. They were owned by coastal farmers and assembled by the king to form the leidang in times of conflict, in order to have a powerful naval force at his disposal. While longships were deployed by the Norse in warfare, there are no descriptions of naval tactics such as ramming, etc. Instead, the ships would sometimes be lashed together in battle to form a steady platform for infantry warfare. Longships were called dragonships (drakuskippan) by the Franks because they had a dragon-shaped prow. [9]
The Karve was a small type of Viking longship, with a broad hull somewhat similar to the knarr. They were used for both war and ordinary transport, carrying people, cargo or livestock. Because they were able to navigate in very shallow water, they were also used for coasting. Karves typically had broad beams of approximately 17 feet (5.2 m).
Viking ships varied from other contemporary ships, being generally more seaworthy and lighter. This was achieved through use of clinker (lapstrake) construction. The planks on Viking vessels were rived (split) from large, old-growth trees—especially oak. A ship's hull could be as thin as one inch (2.5 cm), as a rived plank is stronger than a sawed plank found in later craft, resulting in a strong yet supple hull. [10] Working up from a stout oaken keel and ribs, the shipwrights would rivet on the planks using wrought iron rivets and roves, reinforced with added support ribs and thwarts. Each tier of planks overlapped the one below, and a caulking of tarred cow's hair was used between planks to create a waterproof hull.
Remarkably large vessels could be constructed using traditional clinker construction. Dragon-ships carrying 100 warriors were not uncommon. [11] Furthermore, during the early Viking Age, oar ports replaced rowlocks, allowing oars to be stored while the ship was at sail and to provide better angles for rowing. The largest ships of the era could travel five to six knots using oar power and up to ten knots under sail. [12]
Viking ships were manufactured with techniques that ensured the durability and agility of the ships especially in regards to ships used in warfare.For instance, warships like the 'Skeid' and the 'Snekka' with features of shallow drafts that enabled them to efficiently approach shores and sail up rivers [13] Viking builders used the 'clinker-built' method whereby oak or pine plants are overlapped and fastened with iron rivets and sealed with tar and wool in order to ensure that it is waterproofed [14] . Additionally, shields were often mounted on both sides of the ship for protection as well as portrayal of the idea of strength and power. [15] This method significantly proved to be suitable for Viking ships as it ensured its speed which was ideal for both long journeys and raids.
In addition to this, ships were strengthened with a combination of one floor timbers and crossbeams, therefore enabling the ships to gain structural strength [16] . The keelson approach whereby a heavy timber is placed on the keel in order to stabilize the mast, supported both the longships and narrow ships with shallow drafts [17] . This proved to be significantly ideal for navigating diverse waterways.
With such technological improvements, the Vikings began to make more and more ocean voyages, as their ships were more seaworthy. However, in order to sail in ocean waters, the Vikings needed to develop methods of relatively precise navigation. Most commonly, a ship's pilot drew on traditional knowledge to set the ship's course. Essentially, the Vikings simply used prior familiarity with tides, sailing times, and landmarks in order to route courses. For example, scholars contend that the sighting of a whale allowed the Vikings to determine the direction of a ship. Because whales feed in highly nutritious waters, commonly found in regions where landmasses have pushed deep-water currents towards shallower areas, the sighting of a whale functioned as a signal that land was near.
On the other hand, some academics have proposed that the Vikings also developed more advanced aids to navigation, such as the use of a sun compass. A wooden half-disc found on the shores of Narsarsuaq, Greenland initially seemed to support this hypothesis. However, further investigation of the object revealed that the slits inscribed in the disc are disproportionately spaced, and so the object could not in fact function as an accurate compass. Rather it has been suggested that the instrument is instead a "confession disc" used by priests to count the number of confessions in their parish. [18] Similarly, researchers and historians continually debate the use of the sunstone in Viking navigation. Because a sunstone is able to polarize light, it is a plausible method for determining direction. By showing which direction light waves are oscillating, the sunstone has the potential to show the sun's position even when the sun is obscured by clouds. The stone changes to a certain color, based on the direction of the waves, but only when the object is held in an area with direct sunlight. Thus, most scholars debate the reliability and the plausibility of using a navigational tool that can only determine direction in such limited conditions. [19]
Viking sagas routinely tell of voyages where Vikings suffered from being "hafvilla" (bewildered)—voyages beset by fog or bad weather, where they completely lost their sense of direction. This description suggests they did not use a sunstone when the sun was obscured. Moreover, the fact that this same bewilderment could arise when the winds died suggests that the Vikings relied on prevailing winds to navigate, as expected if their skills depended principally on traditional knowledge. [20]
Viking ships were not only tools for navigation but also cultural symbols with high artistic design value. The carved patterns on Viking ships are known for their intricate geometric patterns, mythological creatures, and symbolic designs, primarily found on the bow, stern, and other wooden structures. These carvings were not only decorative but also embodied the Vikings' cultural and religious beliefs. Common Viking ship carving patterns and themes include animal motifs, geometric designs, mythological scenes, and inscriptions.
Many Viking ships had intricately carved dragon heads or other mythical creatures on the bow and stern. These carvings served as a means to intimidate enemies and protect the sailors during their journeys. These carvings were not merely decorative but symbolized the Vikings' reverence for nature and their societal beliefs. The quality and intricate design of the ship indicated the resources invested by its owner. Many Viking lords and nobles used large, elaborately carved ships to showcase their social status. Thus, ships were not only tools for war and exploration but also symbols of family identity. Possessing a well-carved ship symbolized a family's wealth and influence, highlighting their place in Viking society. [22] The craftsmanship of Viking ships was undoubtedly top-notch for its time. Constructing such a ship required highly skilled artisans and a significant amount of time, with materials and decorative elements often being costly. Therefore, these ships symbolized a family's honor and prosperity. Viking ships were not only works of art but also ways for people to display social status, particularly through their exquisite dragon head carvings and intricate geometric patterns, which reflected the high level of craftsmanship and artistic value.
In some archaeological discoveries, experts found that the hulls of ships were adorned with rich patterns, such as intertwining vines, geometric shapes, or animal totems. These patterns are filled with symbolic meanings, many of which can be traced back to Viking mythology and belief systems. The famous Oseberg Ship, for example, has an interlocking animal motif on its bow: a ribbon-animal, gripping-beasts rendered with humanoid heads, and more ambiguous forms that echo the bodies of creatures seen at the prow. Such style is called the Oseberg Style, which is the first phase of the development of the Viking aesthetic, lasting from the year 775 to the year 850. It is famous for its intertwining zoomorphic patterns of "Gripping Beasts" and "Ribbon-Animals". [23]
This citation from a French historian, a monk at the St. Omer monastery in Flanders, provides a detailed description of Viking ships, focusing on their elaborate decoration and organization. The account mentions that the Viking chieftains' ships were distinguished by unique designs on the bow, including gold lion figures, wind-vanes with birds, and animal carvings of drakes, bulls, and dolphins in bronze or precious metals. The ships' sides were painted in vibrant colors and adorned with wood carvings, particularly the king's vessel, which was the most intricately decorated. This passage serves as valuable evidence of the Vikings' investment in ship artistry as a reflection of power, wealth, and rank. The choice of metal animal motifs and the intricate designs on prominent vessels reveal how these ships were not only functional but also designed to display status and intimidate. [24]
Viking ship carvings are renowned for their smooth, intricate swirling patterns, often found on the hull and other wooden parts of the ship. These patterns are not only beautiful but also contain religious and cosmic symbolism. For example, the interlocking designs symbolize ideas of life cycles and rebirth, resonating with the Norse mythological concept of Yggdrasil, the World Tree. In Viking mythology, Yggdrasil is a giant ash tree representing the center of the universe, connecting the heavens, earth, and underworld. [25] It embodies the interweaving of all life and events. Vikings believed that by carving these patterns on ships, sailors could gain the tree's protective power.
Furthermore, the designs on Viking ships were often symmetrical geometric shapes or repeated curves, which were not only visually appealing but also reflected the Vikings' profound understanding of nature. These decorative styles are common in Viking art, often referred to as "Viking Animal Style" or "Viking Geometric Style." [26] This style indicates the Vikings' appreciation of order, cycles, and vitality, making the ships more than just vehicles; they were spiritual symbols as well.
Viking ships held significant roles in religious rituals, especially in Viking ship burial ceremonies. Vikings believed that death was not the end but a journey to another world. As a vessel that could cross boundaries, the ship became a symbol of this "journey," particularly in the burials of prominent individuals. Ships were used as grave goods to help the deceased "sail" to the afterlife. Large burial ships like the Oseberg Ship provide crucial evidence of Viking burial practices. [27]
In the Viking culture, the sizes of their ships were used as indicators of power and status. In further explanation, during the viking age, the sheer size of the ship, the details and materials used in manufacturing the ship of a viking, publicly portrayed the wealth and power which the owner holds. For instance, extravagant ships like the Longships used by the Viking Chieftains and warriors significantly emphasized on their authority and prestige [28] . Furthermore, in correlation to ship burials like the Oseberg and Gokstad, they highlight how these elaborate and detailed burials pinpoint the fact that ships were placed on a platter of significant value of possessions, that followed individuals of high esteem into the afterlife as a guide [29] . In addition, they also served as a reservation for those in high authority in both life and in death. [30] The ownership of a ship during the Viking Age carried along with it social implications by effectively reinforcing class distinctions and a hierarchy within the Viking society [31] . A well-decorated and elaborated ship represented great wealth and influence due to the reason that only Vikings who were associated with power could access such expensive and delicate materials in the building of such a ship.
Viking ships held a very spiritual significance in the Viking society. As a reflection of the Oseberg ship burial, speculations portray how Viking ships were also used as company for the dead in their journey in the afterlife. In the Viking culture, the dead particularly warriors, were placed in their ships which would be set on fire and sent out to sea by the tides and winds [32] .This practice was seen as a way for Viking warriors to continue their journey of warfare in the afterlife with a guide. Such mythological portrayals emphasize on just how deeply the role of Viking ships were tied into the Viking understanding of life and death. [33] Among myths and spirituality, Nordic Rune Stones were also emblematic of Viking longships, especially in regard to storytelling of Norse mythology. [34]
Viking Ships played prominent roles on not just being symbols of power, but also war. In particular sea battles that fought with an older style of battle. The masts on these longships were lowered during battle with other longships and acted as a battle between makeshift sea fortresses. All members of the crew were considered oarsmen and were proficient in using them. Throughout many battles, longship vessels were the type of ships to make it to the end of this specific warfare and battles were taking place as late as 1429. [35]
Prominent men or women in Norse society sometimes received a ship burial. The body of the deceased would be prepared and dressed in fine clothes and then be transported to the burial-place in a wagon drawn by horses. The deceased would be placed on the ship, along with many prized possessions. Horses, dogs and occasionally thralls and households might also be sacrificially killed and buried with the deceased. The origin and meaning of these customs remain unknown. Several examples of Viking ship burials have been excavated, e.g. the Oseberg ship in Norway, containing the remains of two women, the Gokstad ship in Norway, and the Ladby ship in Denmark.
There are literary sources such as the Norse Skjoldunga Saga and the Ynglinga Saga which describe more literal "ship burials" in which the deceased and goods are placed on a boat in the water and the vessel is launched into the sea, sometimes being shot with burning arrows and vanishing into the night, ablaze. Nothcotte Toller, however, states:
Whether such fiery funerals ever actually took place is impossible to know; but it is much more difficult to imagine that a king's body and accompanying treasures would have been simply pushed out to sea, where they would have been in danger of returning, or of falling into the hands of strangers or even enemies who might maltreat the one and plunder the other. [36]
Burial of ships is an ancient tradition in Scandinavia, stretching back to at least the Nordic Iron Age, as evidenced by the Hjortspring boat (400–300 BC) or the Nydam boats (200–450 AD), for example. Ships and bodies of water have held major spiritual importance in the Norse cultures since at least the Nordic Bronze Age.
Several original Viking ships have been found through the ages, but only a few have been relatively intact. The most notable of these few ships include:
Examples of other Viking ships, including some that are relatively well-preserved and some, where only very small parts remain:
Have been regarded as Viking ships, but from before or after the Viking Age:
Viking ship replicas are one of the more common types of ship replica. Viking , the first Viking ship replica, was built by the Rødsverven shipyard in Sandefjord, Norway. In 1893 it sailed across the Atlantic Ocean to Chicago for the World's Columbian Exposition. There are a considerable number of modern reconstructions of Viking Age ships in service around Northern Europe and North America. The Viking Ship Museum in Roskilde, Denmark, has been particularly prolific in building accurate reconstructions of archaeological finds in its collection.
Longships were a type of specialised Scandinavian warships that have a long history in Scandinavia, with their existence being archaeologically proven and documented from at least the fourth century BC. Originally invented and used by the Norsemen for commerce, exploration, and warfare during the Viking Age, many of the longship's characteristics were adopted by other cultures, like Anglo-Saxons, and continued to influence shipbuilding for centuries.
A ship burial or boat grave is a burial in which a ship or boat is used either as the tomb for the dead and the grave goods, or as a part of the grave goods itself. If the ship is very small, it is called a boat grave. This style of burial was practiced by various seafaring cultures in Asia and Europe. Notable ship burial practices include those by the Germanic peoples, particularly by Viking Age Norsemen, as well as the pre-colonial ship burials described in the Boxer Codex in the Philippines.
The koch was a special type of small one- or two-mast wooden sailing ships designed and used in Russia for transpolar voyages in ice conditions of the Arctic seas, popular among the Pomors.
The Gokstad ship is a 9th-century Viking ship found in a burial mound at Gokstad in Sandar, Sandefjord, Vestfold, Norway. It is displayed at the Viking Ship Museum in Oslo, Norway. It is the largest preserved Viking ship in Norway.
The Oseberg ship is a well-preserved Viking ship discovered in a large burial mound at the Oseberg farm near Tønsberg in Vestfold county, Norway. This ship is commonly acknowledged to be among the finest artifacts to have survived from the Viking Age. The ship and some of its contents are displayed at the Viking Ship Museum at Bygdøy on the western side of Oslo, Norway.
Clinker-built, also known as lapstrake-built, is a method of boat building in which the edges of longitudinal (lengthwise-running) hull planks overlap each other. Where necessary in larger craft, shorter hull planks can be joined end to end, creating a longer hull plank (strake).
Viking art, also known commonly as Norse art, is a term widely accepted for the art of Scandinavian Norsemen and Viking settlements further afield—particularly in the British Isles and Iceland—during the Viking Age of the 8th-11th centuries. Viking art has many design elements in common with Celtic, Germanic, the later Romanesque and Eastern European art, sharing many influences with each of these traditions.
The birlinn or West Highland galley was a wooden vessel propelled by sail and oar, used extensively in the Hebrides and West Highlands of Scotland from the Middle Ages on. Variants of the name in English and Lowland Scots include "berlin" and "birling". The Gaelic term may derive from the Norse byrðingr, a type of cargo vessel. It has been suggested that a local design lineage might also be traceable to vessels similar to the Broighter-type boat, equipped with oars and a square sail, without the need to assume a specific Viking design influence. It is uncertain, however, whether the Broighter model represents a wooden vessel or a skin-covered boat of the currach type. The majority of scholars emphasise the Viking influence on the birlinn.
The Hjortspring boat is a vessel designed as a large canoe, from the Scandinavian Pre-Roman Iron Age. It was built circa 400–300 BC. The hull and remains were rediscovered and excavated in 1921–1922 from the bog of Hjortspring Mose on the island of Als in Sønderjylland, southern Denmark. The boat is the oldest find of a wooden plank ship in Scandinavia and it closely resembles the thousands of petroglyph images of Nordic Bronze Age ships found throughout Scandinavia. The vessel is a clinker-built wooden boat of more than 19 metres length overall, 13.6 metres long inside, and 2 metres wide. Ten thwarts that could have served as seats, span the boat with room for two persons each; this suggests space for a crew of at least 20 who propelled the boat with paddles. The boat would have weighed an estimated 530 kilograms, making it easily portable by its crew.
The Viking Ship Museum is located on the Bygdøy peninsula in Oslo, Norway. It is temporarily closed from September 2021 until 2027.
A knarr is a type of Norse merchant ship used by the Vikings for long sea voyages and during the Viking expansion. The knarr was a cargo ship; the hull was wider, deeper and shorter than a longship, and could take more cargo and be operated by smaller crews. It was primarily used to transport trading goods like walrus ivory, wool, timber, wheat, furs and pelts, armour, slaves, honey, and weapons. It was also used to supply food, drink, weapons and armour to warriors and traders along their journeys across the Baltic, the Mediterranean and other seas. Knarrs routinely crossed the North Atlantic carrying livestock such as sheep and horses, and stores to Norse settlements in Iceland, Greenland and Vinland as well as trading goods to trading posts in the British Isles, Continental Europe and possibly the Middle East. The knarr was constructed using the same clinker-built method as longships, karves, and faerings.
The Ladby ship is a major ship burial at the village of Ladby near Kerteminde in Denmark. It is of the type also represented by the boat chamber grave of Hedeby and the ship burials of Oseberg, Borre, Gokstad and Tune in South Norway, all of which date back to the 9th and 10th centuries. It is the only ship burial from the Viking Age discovered in Denmark. It has been preserved at the site where it was discovered, which today is part of a museum.
The vinta is a traditional outrigger boat from the Philippine island of Mindanao. The boats are made by Sama-Bajau, Tausug and Yakan peoples living in the Sulu Archipelago, Zamboanga peninsula, and southern Mindanao. Vinta are characterized by their colorful rectangular lug sails (bukay) and bifurcated prows and sterns, which resemble the gaping mouth of a crocodile. Vinta are used as fishing vessels, cargo ships, and houseboats. Smaller undecorated versions of the vinta used for fishing are known as tondaan.
The Skuldelev ships are five original Viking ships recovered from the waterway of Peberrenden at Skuldelev, c. 20 km (12 mi) north of Roskilde in Denmark. In 1962, the remains of the submerged ships were excavated in the course of four months. The recovered pieces constitute five types of Viking ships and have all been dated to the 11th century. They are thought to have been an early form of blockship, i.e. ships that were scuttled to block potential invasions from the sea. The numbering of the ships is slightly confusing as when the remains were unearthed, they were thought to comprise six ships, but after "Skuldelev 2" and "Skuldelev 4" were later discovered to be parts of one ship, it was decided not to renumber the other vessels.
A faering is an open boat with two pairs of oars, commonly found in most boat-building traditions in western and northern Scandinavia.
Medieval ships were the vessels used in Europe during the Middle Ages. Like ships from antiquity, they were moved by sails, oars, or a combination of the two. There was a large variety, mostly based on much older, conservative designs. Although wider and more frequent communications within Europe meant exposure to a variety of improvements, experimental failures were costly and rarely attempted. Ships in the north were influenced by Viking vessels, while those in the south by classical or Roman vessels. However, there was technological change. The different traditions used different construction methods; clinker in the north, carvel in the south. By the end of the period, carvel construction would come to dominate the building of large ships. The period would also see a shift from the steering oar or side rudder to the stern rudder and the development from single-masted to multi-masted ships. As the area is connected by water, people in the Mediterranean built different kinds of ships to accommodate different sea levels and climates. Within the Mediterranean area during the Medieval times ships were used for a multitude of reasons, like war, trade, and exploration.
Viking ship replicas are one of the more common types of ship replica. Viking, the first Viking ship replica, was built by the Rødsverven shipyard in Sandefjord, Norway. In 1893 it sailed across the Atlantic Ocean to Chicago in the United States for the World's Columbian Exposition. Formerly located in Lincoln Park, Chicago, Illinois, the Viking is currently undergoing conservation in Geneva, Illinois, United States.
Traditionally, many different kinds of boats have been used as fishing boats to catch fish in the sea, or on a lake or river. Even today, many traditional fishing boats are still in use. According to the United Nations Food and Agriculture Organization (FAO), at the end of 2004, the world fishing fleet consisted of about 4 million vessels, of which 2.7 million were undecked (open) boats. While nearly all decked vessels were mechanised, only one-third of the undecked fishing boats were powered, usually with outboard engines. The remaining 1.8 million boats were traditional craft of various types, operated by sail and oars.
Draken Harald Hårfagre is a large modern designed longship built in the municipality of Haugesund, Norway. It is a ship that combines ocean-crossing sailing capabilities with a medieval warship's use of oars.