IT'S 600 YEARS since Admiral Zheng He, the intrepid Ming dynasty naval explorer set out on the first of seven landmark voyages which took him to Southeast Asia, India, the Persian Gulf, the Red Sea, and as far as the east coast of Africa. In this anniversary year, a modern-day Admiral Zheng - retired Rear Admiral Zheng Ming of the People's Liberation Army navy - is building a seaworthy replica of Zheng He's famous 'treasure ship' with the aim of following his routes. 'Zheng He's route is the Silk Road of the sea,' says the affable admiral when we meet in a Beijing teahouse. A senior member of a group devoted to studying the achievements of Zheng He - who also was known as Cheng Ho - the modern-day mariner becomes animated when discussing the project to build the replica ship. Emperor Yongle, the first ruler of the Ming dynasty, wanted to showcase China's naval power and in 1402 commissioned Admiral Zheng He, a Muslim eunuch from Yunnan province, to undertake a daring mission to the seas known to the Chinese as the 'Western Oceans'. Three years later, the expedition was ready and it is this historic event that the 600th anniversary marks. Zheng He's journeys took him to 37 countries over 28 years. It is believed by some to be the mightiest fleet that ever sailed, with 300 ships and 37,000 sailors. The pride of the fleet was the treasure ship, a stunning vessel about 130 metres long and with 1,000 men on board. It is a replica of this ship that Admiral Zheng's group, which is known as the Beijing Association for the Studies of Zheng He's Voyage, wants to build. The problem with building the replica, being constructed in Zhoushan, Zhejiang province, and which is should be finished by the end of the summer, is that no one really knows what the ships looked like. No such vessels exist today, leaving the boat-builders to try to recreate the vessels from documentary evidence. It's a procedure involving much experiment, trial and error. The first sail was made of bamboo weave, but then the decision was made to construct it from canvas. It's still undecided what the final version will be. 'There are 10,000 questions to answer when building a boat,' the admiral says. 'What wood did they use? If that wood doesn't exist any more, what do we use? We're gradually learning how to build the real thing by research. Thousands of ships were built but none still exist, not even as shipwrecks.' Rear Admiral Zheng worked through the ranks of the modern navy, 'from an average sailor with a cleanly shaved head to a decorated officer'. He graduated from the naval architecture facility of Shanghai Jiaotong University and joined the navy almost 50 years ago. For 10 years he was the director of the Naval Armament Department, and designed nuclear-powered submarines and destroyers. In approaching his pet project, he combined his naval engineering skills with those of a traditional boat-builder, Chen Guohe in Zhoushan, to come up with a model of the treasure ship. The replica will be 61 metres long, as a lack of information about the original flagship means making a bigger ship is technically too difficult. Earlier efforts to build a replica have sunk, but the admiral remains confident. He went through old documents and managed to duplicate many of the individual aspects of the boat - including the keel, frame, deck, sails, anchor, mast, helm and bottom plate. Then it was a question of putting them all together to create a seaworthy vessel. The devil is in the details. For example, there were no records of what lamps would be used on a ship in Zheng He's time, so they had to work it out from other historical sources. Zheng He's amazing exploits have become a focal point for Chinese nationalism, although his modern namesake is keen to point out that his group is a non-governmental organisation and relies on donations to support its efforts. In the days when the intrepid admiral, who became known as the 'three-jewelled eunuch', roamed the high seas, China was far more technologically advanced than other cultures and had no equal at sea. Once the replica is built, the first step will be to sail up and down the Chinese coast, from Nanjing to Changle to Guangzhou, and also to visit Hong Kong. Crewing details have still to be worked out, but the admiral says he's unlikely to captain the ship. The second step is to travel around Southeast Asia, and the third stage will be to take the boat around the world by the end of the decade. China has been keen to push the Zheng He story as a symbol of Chinese ingenuity, but also of its benign foreign policy. Admiral Zheng points out that Zheng He was not a coloniser. He never built a fort and was more interested in trade than theft, although the fleet was also supposed to spread the word to the peoples of southern Asia in particular that China was a mighty power. 'Zheng He's fleet brought Chinese inventions with them - fishermen in Sri Lanka still use nets today that they call China nets,' the admiral says. 'It was very different from Christopher Columbus - wherever he went he made the locals slaves and robbed their natural resources. 'In the Ming dynasty, the policy was to bring help to weak and small countries. This has an international meaning nowadays - big countries should not prey on small ones and developed countries should help smaller ones instead of depriving them of their natural resources.' Born Ma He in 1371, to poor parents, the future great seafarer was captured by soldiers and castrated when he was still a boy. He was forced into the army, where he excelled, and also studied languages and philosophy. He died in 1433, aged 62. Zheng He sailed for nearly 30 years but after the emperor died in 1424, China began to look inwards, beginning a policy of isolationism that lasted hundreds of years. 'The Ming dynasty was the peak of China's power and we want to awaken Chinese pride and show the importance of openness,' says Admiral Zheng. 'After the Ming dynasty, China turned its back on foreign countries. In the 15th and 16th centuries, some small European countries like Spain and Portugal developed a lot, while China went backwards.' There will be many events this year to mark the 600th anniversary on July 11, including conferences, special TV programmes and fairs in China and Hong Kong. Zheng He received international attention after the publication of British author Gavin Menzies' book, 1421, which claims Zheng reached the Americas that year. Menzies, a former submariner, presented evidence at the Foreign Correspondents' Club in Hong Kong last year to support his claims that the first explorers who circumnavigated the globe were not Europeans, but Chinese. Some of the evidence for his book was based on the findings of Lam Yee-din, an unemployed electrical engineer from Hong Kong, who discovered 26 charts in Hong Kong's Central Library of Zheng He's apparent 1408 voyage to Europe. Despite this evidence, other historians dispute Menzies' claims. The two Zhengs have a lot in common besides their surnames and ranks. 'We're not related but we do share a lot of experiences - he spent 28 years on the sea, I spent more than 50 years at sea,' Admiral Zheng says. 'We both have a very great feeling for the sea.' His work now is to raise awareness in China of Zheng He. 'I was very disappointed during a recent Chinese beauty pageant when a contestant was asked to name a famous explorer. She answered Columbus rather than Zheng He. Imagine.'