ROMAN MERCHANT SHIPS — WARHORSES of the ANCIENT WORLD

Divers Gather Amphorae from a Shipwreck

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At its peak, the Roman Empire completely encircled the Mediterranean Sea, which First Century Romans conveniently called Mare Nostrum, or Our Sea. Not only did its waters provide fish to feed citizens from Mauritania to Hispania, it also facilitated inter-Empire trade between the various Provinces. Rome had a vigorous, far-flung, and diverse trade network that extended far beyond their borders to India and China.  

ROME’S MERCHANT MARINE

Roman merchants moved all sorts of goods and foodstuffs by sea. Commercial vessels were known by a variety of names, such as corbita, gaulus, ponto, or cladivata, depending upon the region. Overall, the ships demonstrated great uniformity in design. This would be expected given the level of maritime commerce within the Empire. Innovations and improvements were quickly shared and disseminated within the industry.

Museum Reproduction of a Roman Corbita

LEARNING FROM DISASTER

Our knowledge of Roman shipping comes from two sources, ancient drawings and illustrations, and shipwrecks. The large number of shipwrecks found around the Mediterranean illustrates not only the quantity of shipping that took place, but the perils of traveling by sea in earlier times. We can verify this based on the detailed account in Acts of the Apostles of Paul being shipwrecked on his way to Rome. Depending on size and intended use of the ship, the hull shape could be either symmetrical or asymmetrical. In the first case the stern and bow were essentially identical. In the asymmetric version, the bow was located at a lower height. The bow was sometimes concave, due to the presence of a cutwater. These were added not as a ram, but a structural modification to improve the vessel’s sailing ability.  

WIND-POWERED TRANSPORT

Unlike the warships that utilized rowers to quickly maneuver and propel the ship, merchant ships relied exclusively upon sails for propulsion. The illustrations I’ve used show a single-masted ship, however as the vessel’s size and tonnage increased they added a second and even a third mast. The sails were square and controlled by a complex system of rigging. Many ships also featured a smaller sail, called a supparum, on the bow which aided steering.

BIG, BIGGER, AND BIGGEST

The size of Roman ships often surprises people. On the low end were ships designed for the grain trade, which carried 10,000 modii of grain…a little over 75 tons. These were the workhorses of the fleet running regular routes to nearby Provinces to load wheat or barley. A government contract provided the ship owner with a steady source of income as his ship traced and retraced the same path back and forth between Rome and Sicily, Alexandria, or other export points.  

Medium-sized ships were used extensively for the olive oil trade and were measured by the number of amphorae they could hold. A 3,000-amphora vessel had almost three times the capacity of the smaller ships, carrying 165,000 tons. The size of these ships is confirmed by numerous underwater explorations of ship wrecks. In addition to the specialized use previously mentioned, small and medium-sized ships hauled general merchandise as well. Metal ores and other raw materials, spices, silk and other trade goods moved with surprising regularity. For instance, in the First Century 120 ships a year set sail for India from the Red Sea port of Berenike. Their return cargo consisted of pepper which was moved by barge to Alexandria, and from there to Rome on still more ships. 

The Roman fleet also had higher tonnage vessels. The hull of the Madrague de Giens, that floundered off Gaul (France) in the First Century BC, was 130 feet long with an estimated capacity of 440 tons. In the early years of the Roman Empire, the muriophorio, 10,000-amphora carriers carrying 550 tons were the largest ships afloat. The grain trade also utilized some 50,000 modii vessels which hauled 365 tons. The size and capacity of these ships was not exceeded in the Mediterranean until the Sixteenth Century.  

Yet the Roman world saw a few ships larger even than these. For instance, the carrier that Caligula built to transport an obelisk from Egypt to Rome had a capacity of 1450 tons. After it sank, it was used to construct the lighthouse at the port of Claudius. Various Emperors, Cleopatra among them, built barge-like floating palaces. Though designed for limited use in safe waters, some of them were nearly 250 feet in length.

The Merchant Ship Afloat

STANDARDIZED SHIPPING CONTAINERS

For olive oil and many other commodities, amphorae became the standard shipping container. So many amphorae arrived in Rome that disposing of the empties eventually created a problem. In 1999 an underwater search for a lost Israeli submarine turned up an ancient shipwreck at a depth of 10,000 feet. The ship came to rest on its keel then gradually tipped to one side. The weight of the amphorae in its hold caused the hull to lose structural integrity, spreading an oval mound of amphorae approximately 80 feet long and 50 feet wide on the seafloor. It is estimated that there are 2,500 amphorae in the pile. Based on its location halfway between Rhodes and Alexandria and the Greek wine it carried, archeologists surmise the ship was headed for Egypt.  

When hearing the word amphora, many people think of an urn-like container. In fact, amphora is also a unit of measurement. An amphora equaled 3 modius. Since a modius contains 2 ½ gallons of liquid, each amphora on the seafloor represents 7½ gallons. So, if the 2,500 intact amphorae comprised the entire cargo, the ship was carrying 18,750 gallons, or 150,000 pounds, of wine when it sank.  

Like most colonizing powers, over time Rome grew dependent upon the influx of goods from the Provinces to survive. Each year 60,000,000 modii of grain arrived in Rome. Assuming each vessel contained 50,000 modii, that works out to 1,200 shipments of grain annually. Navigation was not the year-round affair that it is today. Every winter saw the arrival of the mare clausum or closed sea that lasted four months. Subtracting this period of inactivity computes to an average of five large grain ships arriving every navigable day. It has also been calculated that seven or more large shiploads of olive oil docked each month. To those must be added the ships that transported wine, fish products, spices, cloth, ore, marble and stone blocks. There were also shiploads of wild animals arriving from Africa and elsewhere for use in the games.    

All of this merchandise directed at Rome had to come through the Port of Ostia and later the Port of Claudius. Merchant ships which exceeded a 3000-amphora capacity, about 165 tons, could not travel upstream. They were obliged to anchor at sea and unload their cargo onto smaller vessels which shuttled between the ships and the river entrance to the Port of Ostia. These operations were lengthy and dangerous operations. The coastline in that area was inhospitable, low, and sandy.  

Next time we’ll examine the ancient method of contemplative study of the scriptures known as Lectio Divina.

Until then, we wish you Peace and Blessings

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