Business is booming for small ships that can unload cargo without berthing at wharves although most are unqualified for shipping operations, according to local maritime officials.
The practice endangers the safety of both their own boat and other vessels in the harbor, officials said yesterday.
The ships, commonly referred to as "self-unload ships" in the industry,  are working at the mouth of the Yangtze River, moving to and from neighboring provinces and local harbors to supply Shanghai with stone.
Authorities estimated there are up to 200 self-load ships based in neighboring Zhoushan waters in Zhejiang Province.
"The increasing need for construction-use stone in recent years have attracted many ship owners, especially fishermen from some parts of Zhejiang Province," said maritime official Wang Cheng'ai. "Many have refitted their ships into self-unload cargo vessels to enter the business."
Using a conveyor belt-like system from the boat to the shore, the vessels easily unload goods by stopping close to the riverbank.
Vessel owners avoid supervision from the maritime administration and cut operating costs as they avoid wharf fees.
But the small ships are fragile and can be dangerous when operating in inclement weather.
"The ships are not stable enough," Wang said. "Any big wave could cause them to capsize."
Another problem is that few ship workers - most were farmers or fishermen previously - have received any professional training, officials said.
One self-load ship capsized on July 26, killing three people, on its way to transporting 980 tons of stone to Luchao Harbor in the city. The self-load ship carried 460 tons more than its load limit.
Three self-load ships have sunk in Yangshan Deep Water Port this year, causing 10 deaths.
Maritime authorities said self-load ships working without licenses or in poor conditions would face severe fines.