GUANGZHOU, Oct. 29-- Chinese archeologists have started a full examination of the Nanhai No. 1, the wreck of an ancient Chinese merchant ship currently preserved in a giant tank of water.

The project is expected to last three to four years, according to the Marine Silk Road Museum in Yangjiang, a city in south China's Guangdong Province.

The Nanhai No.1 dates back to the Southern Song Dynasty in the 13th century. It was raised from the bed of the South China Sea at the end of 2007, along with much of its cargo.

Archeologists will work at the museum, in the tank designed to house the ship of about 30 meters in length and a 10 meter beam.

Archeologists estimate there are about 60,000 to 80,000 antique items in the wreck, most being porcelain, precious metal objects and coins.

Over 6,000 pieces of porcelain, copper and other treasure were salvaged in two trial excavations in 2009 and 2011.