Archaeologists Reveal Secrets of Merchant Ship That Sank in 15th Century

A team of archaeologists has investigated the wreck of a boat that sank in the 15th century, revealing fascinating new insights into the stricken vessel.

The so-called "Maderö wreck" was first discovered in the 1960s in the waters of the Stockholm Archipelago—a large group of islands scattered off the coast of mainland Sweden in the Baltic Sea.

The divers who found the wreck made a sketch of the site, which shows a large, partly disintegrated wooden hull laden with bricks from what seemed to represent a medieval vessel.

Then in the 2000s, further dives at the wreck underlined the medieval dating, although the archaeological documentation was neither completed nor published at this stage, leaving many questions unanswered.

It was not until recently that the opportunity to continue investigating the site arose. In 2022, a team of researchers led by Niklas Eriksson, with the Department of Archaeology and Classical Studies at Stockholm University, conducted an investigation, which included the inspection and documentation of visible ship parts, as well as the taking of numerous samples.

These investigations, the results of which have been published in the International Journal of Nautical Archaeology, have yielded new information on the wreck.

"The reason we decided to have a closer look at the Maderö wreck is that we have limited knowledge about ships from this period," Eriksson told Newsweek. "The character of the wreck site is favorable as several crucial and informative parts of the hull are visible above the seabed and the cargo is easily accessible. This means that a lot of information can be extracted from the site with a limited impact on the remains."

Among the findings, the team learned a significant amount about the main dimensions and proportions of the medieval merchant ship. The study revealed that the original length of the ship, for example, was more than 65 feet, while the breadth of the hull was approximately 26 feet. This makes the Maderö ship a relatively large vessel by late medieval standards, even if there are several ships from the period that are bigger.

The team's analysis also revealed that the wood used to construct the ship was felled after 1467. This means the sinking occurred after this date, although the researchers have not yet determined the exact timing.

"It has not been possible to determine the year [the ship] sank but it seems likely that it happened during the last decades of the 15th century," Eriksson said.

The archaeologists also determined where the wood came from, as well as the bricks. The origin, or provenience, of the wood from different areas, indicates that the ship was—at least partly—built from imported wood rather than relying solely on local supply.

"Thanks to the provenience of the wood, which turned out to be from two different areas, we may use the Maderö wreck as an example of the trade in wood and shipbuilding material in the Baltic Sea area in the 15th century," Eriksson said.

"The provenience of the clay used in the bricks and tiles is very interesting in this context as it, to some extent, corresponds with the provenience of the wood. To find a ship loaded with bricks from Lübeck [in Germany] in the sea route towards Stockholm is surprising as it has been assumed that the medieval bricks in Stockholm were made locally."

Finally, the study found that stone shots found at the wreck site indicate that the ship was likely armed when it sank.

"To what extent merchant ships were armed during the 15th century is not known, so the Maderö wreck provides some important clues here," Eriksson said.

There were several conflicts going on in the Baltic Sea region during the 15th century, which would have provided a good reason for the merchant ship to be armed.

For instance, there were several uprisings and conflicts within the Kalmar Union that unified Denmark-Norway and Sweden between 1397 and 1523 and between the Kalmar Union and the Hanseatic League—an organization of market towns and merchant communities, primarily in northern Europe, designed to protect their mutual trading interests.

"Merchant ships were attacked and captured by all the warring parties," Eriksson said.

According to the researchers, the latest findings also have a number of wider implications.

"Together with other wrecks, we can use the results from the Maderö wreck to draw a fuller picture of what a big late medieval merchant ship looked like. The survey has definitely contributed to the knowledge within this field and to the shipping and trade with wood and shipbuilding material."

Update 1/26/24, 10:51 a.m. ET: This article has been updated with additional comments from Niklas Eriksson.