More than 600 years ago, the legendary Chinese Muslim explorer Zheng He was said to have sailed to the Arabian Peninsula and Africa in ships that dwarfed in size those of later European adventurers.
Zheng He's replica ship sailing into the future on wave of past glory
BEIJING // More than 600 years ago, the legendary Chinese Muslim explorer Zheng He was said to have sailed to the Arabian Peninsula and Africa in ships that dwarfed in size those of later European adventurers.
His achievements in leading seven voyages, and the supposed size of the vessels in his fleet, offer a convenient perspective for China's present-day rulers. They are presenting themselves as the people returning China to the glories, both in terms of maritime power and of the country's overall global significance, of this previous golden age.
The nation this week put into service its first aircraft carrier, a refitted former Soviet vessel.
Stephen Davies, a Zheng He specialist and consultant to Hong Kong Maritime Museum, says the explorer's voyages and the purported size of his ships are used as part of a "broad government campaign to boost China's international image".
His voyages indicate the country was a global power and so, in building up its military in modern times, China is simply assuming its "rightful role".
Yet centuries on, controversy rages about what Zheng really did and how large were the ships commanded by the explorer, who was a member of China's Hui community.
While academics largely dismiss the British author Gavin Menzies's claims in his bestselling book "1421" that Zheng reached North America ahead of the European explorer Christopher Columbus, and that he also discovered Australia, the ship size issue divides scholarly opinion.
According to the Ming Shi, the official account of the Ming Dynasty, which lasted from 1368 to 1644, the vessels were "44 zhang" or about 137 metres in length.
A ship this large would have towered over those of Columbus, whose Santa Maria flagship, launched in 1460, was believed to be only about 26m long.
But the 44-zhang dimension could be a vast exaggeration, as a stone tablet in Nanjing suggests Zheng's vessels were about 71 metres long.
"I was at a conference where two scholars came to blows because one wanted to believe they were [137 metres] and another wanted to question that," said Sally Church, a Ming Dynasty specialist at the University of Cambridge.
A new study written by Ms Church and two naval architects, Terry Little and John Gebhardt, has tried to answer the question of how vast the vessels could have been.
Due to be published by the Singapore-based International Zheng He Society, the research looks at the loads, bending and shear stresses a 137-metre ship would have been subjected to.
It found a very thick hull could have coped with, among other things, the shear forces - those that run parallel to the hull's surface - generated by the sea.
"Our calculations show that a 450-feet [137-metre] treasure ship could be built to withstand reliably the rigours of open ocean travel if the ships were well-built with a hull of sufficient hull thickness, to the order of two to three feet," says the research.
Ms Church, however, cautions that the study's conclusion was based on many assumptions. For example, it assumed advanced shipbuilding techniques would have been available to connect the planks that made up the vessel, which would have been far larger than any other wooden ships of the time.
"I don't think it could've been possible. On the other hand there isn't hard evidence on either side," she said. She thinks they were about half as long as is sometimes believed, and in a 2005 paper indicated the measurements given in the Ming Shi ultimately came from a novel.
Mr Davies also doubts the ships were as big as is claimed.
"I don't think there is any really credible evidence to support the massive measurements, which themselves appear to have been derived from only one source," he said.
Indeed, a project to build a replica vessel and recreate the voyages of Zheng, who lived from 1371 to 1433, is based around the idea the ships were much less than 137 metres long.
The 71.1-metre replica is being built in Nanjing, China's capital during Zheng's time, and the city where some or all of his vessels were built.
Boasting a 38-metre mast and with sails that will cover 600 square metres, the vessel has been described as the world's largest handmade ship.
It is due to take to the high seas in two years, with its volunteer sailors ultimately aiming to recreate Zheng's seven famous voyages undertaken between 1405 and 1433.
While it may never be possible to definitively say how large Zheng's ships were in the absence of archaeological evidence, the story of his exploration will continue to be important to China, both in terms of its self-perception and how it offers an image of itself to the outside world.
Just as some emphasise the supposed vast size of Zheng's ships to promote the idea of China's former greatness, so the "more belligerent" aspects of his voyages are often underplayed in official accounts, said Mr Davies.
For example, Zheng once captured a Sri Lankan king and brought him back to China, and the armed forces he commanded are said to have sometimes used violence to establish control over trade in the areas they visited.
"It is … an important story for projecting an idea that China's method of maritime expansion is peaceable," said Mr Davies.
By airbrushing out the more controversial activities of Zheng, China tries to show its current naval build-up is part of what officials have described as a "peaceful rise".
"It probably helps them portray themselves as good in the world … generous," said Ms Church.