Almost 400 years ago, the Dutch ship Batavia sank on its maiden voyage. Now scientists have studied the rings in the ship’s timber to explain a mystery of 17th-century shipbuilding. They had to invent new techniques in wood sampling to do this, requiring 15 years of work to design and implement, but their solution could be used to settle other historical mysteries.

Despite being much smaller and resource-poor than its competitors, the Netherlands became a major maritime power with colonies from the Americas to South East Asia. Some of the ingredients of their success, such as their early adoption of wind power, are familiar to historians, but other secrets have been lost.

Shipwreck detective Dr Wendy van Duivenvoorde of Flinders University led the team, which has used the fate of one of the less successful Dutch vessels to solve one mystery in PLOS ONE.

Europe's conquest of the world depended on fleets that could not be made of just any old wood. Access to suitable timber was vital. The Netherlands didn't have enough of their own to build the 706 ships the Dutch East India Company produced in the 17th century alone, leaving historians wondering the source of their wood.

Van Duivenvoorde told IFLScience; “We know the Netherlands ran a market for timber from around Europe, but the auction records don't start until about 1650. National archives are missing a lot of entries before then.” van Duivenvoorde told IFLScience. 

Sailing was a dangerous business at the time, and the Company’s ship the Batavia sank off Australia’s Morning Reef on its way to the port after which it was named (now called Jakarta). In the 1970s parts were retrieved and displayed at Fremantle’s Shipwrecks Museum. van Duivenvoorde and co-authors realized this presented a rare opportunity to study the wood from which the Dutch ships were made and identify where it came from.

“The preferred material for ship-building was oak,” van Duivenvoorde told IFLScience. “Below the waterline this was fine-grained slow-growing oak. We found this came from the Baltic region, where trees usually grow straight, making the wood more workable.” The Batavia’s frames were built with more crooked oak from lower Saxony. Other parts used pine, whose origins have not been established. “The preference for specific timber products from selected regions demonstrates that the choice of timber was far from arbitrary,” first author Dr Aoife Daly of the University of Copenhagen said in a statement.

Van Duivenvoorde explained to IFLScience that identifying the origins of the Batavia's wood involved two challenges. The first is that wood that has spent centuries underwater is usually in such poor condition it is impossible to take the cores needed, ruling out most Dutch East India Company ships for study even when their resting place is known. Even with the Batavia on land, the team took years to establish a way to protect the wood while collecting cores.

Having managed this, the team scanned databases of tree rings collected from oaks of known origin used for buildings. These rings have been studied extensively, since they provide a record of Europe's climate over the last millennium, helping to reveal how anomalous the last 50 years have been. The database created in the process provided an invaluable resource for the paper's authors, who could find the exact sequence of good and bad growth matching each part of the Batavia's to identify the forest from which the wood came, and the years in which it grew, revealing the last few year’s growth was removed for greater resilience.

Obtaining the wood was only half the shipmakers' challenge. The Dutch use of wind-powered sawmills and better hull design allowed them to create the world’s largest oceanic fleet.