SHIPPER say they must struggle to meet the compliance costs of a new requirement to weigh containers before they're loaded on ships from July 2016, a step carriers say will reduce accidents, reports the Wall Street Journal.

Underestimating container weights has been blamed for some recent maritime disasters, including the MSC Napoli, which suffered hull damage during a storm in the English Channel in 2007. 

But that charge, blaming overweight containers for the Napoli loss, has not been proven, and is based on largely anecdotal evidence. 

Now retailers, manufacturers and farmers are protesting compulsory weigh-ins of containers because it will raise transport costs and cause delays at ports worldwide.

The United Nations rule, enacted by its International Maritime Organisation (IMO), will require exporters to certify the weight of containers before they're loaded in 171 countries. 

But shippers say they are ill equipped to weigh so many containers. In a survey of shippers, carriers, and others involved in global trade conducted by container booking service INTTRA, 57 per cent of respondents were only vaguely familiar or not aware of the rule, and nearly 60 per cent did not believe shippers would be ready by July.

"The industry has been slow in making shippers aware,?said Juerg Bandle, senior vice president of sea freight for Swiss logistics company Kuehne + Nagel. "Now the industry is under time pressure to implement. It will be very challenging.? 
"There is serious concern that there are not even enough third-party scale providers to handle this service for the heavy container volumes,?said Beverly Altimore, executive director of the US Shippers Association.

The US Coast Guard hasn't released details of how it will enforce the weighing rule and declined to say when it would. 

China's Transport Ministry has been conducting trials at Shenzhen's Yantian Port. The ministry will issue regulations and guidance on the rule in the first half of next year, the official said.

The China Shippers' Association has expressed concerns to the ministry that the rule would "incur additional charges and reduce efficiency to the supply chain process,?said Cai Jiaxiang, the group's vice chairman.

The World Shipping Council, representing carriers, said shippers have enough information to comply.

"Nobody should be waiting for national guidelines before taking steps to implement the weight requirement,?said John Butler, the group's president.

Germany's Hapag-Lloyd, the fourth biggest container line, will leave containers that are too heavy at the docks.

Terminal operators at the Port Authority of New York and New Jersey plan to turn away containers if they aren't certified, said Bethann Rooney, assistant director of the Port Authority's commerce department.

APM Terminals, Maersk's port operating unit, may offer weighing services to shippers for a fee, said Thomas Boyd, a spokesman. APMT would set up scales near its ports, and is still working out pricing, he said.

But crops such like cotton and lumber can swell in humid environments, increasing their weight, said Peter Friedmann, executive director of the Agriculture Transportation Coalition.

"Putting the entire burden on the shipper is not fair,?he said.

Asked what the actual evidence was for overweight containers causing accidents, Maersk North Asia CEO Robbert van Trooijen told the Hong Kong Shipping Gazette there wasn't much.

Given the vast scale of Maersk operations, the risk was "relatively small", said Mr Van Trooijen.

"Whilst all incidents are recorded, there is not central repository across the various modes of transport (vessel, rail, truck, depot) to record every mis-declared weight incident," he said.