Rolls-Royce's Blue Ocean development team has set up a virtual-reality  prototype at its office in Alesund, Norway, that simulates 360-degree views from  a vessel's bridge. Eventually, the London-based manufacturer of engines and  turbines says, captains on dry land will use similar control centres to command  hundreds of crewless ships.

Drone ships would be safer, cheaper and less polluting for the $375-billion  US shipping industry that carries 90 per cent of world trade, Rolls-Royce says.  They might be deployed in regions such as the Baltic Sea within a decade, while  regulatory hurdles and industry and union skepticism about cost and safety will  slow global adoption, said Oskar Levander, the company's vice-president of  innovation in marine engineering and technology.

"Now the technology is at the level where we can make this happen, and  society is moving in this direction," Levander said. "If we want marine to do  this, now is the time to move."

The European Union is funding a $4.8-million study called the Maritime  Unmanned Navigation through Intelligence in Networks project. The researchers  are preparing the prototype for simulated sea trials to assess the costs and  benefits, which will finish next year, said Hans-Christoph Burmeister at the  Fraunhofer Center for Maritime Logistics and Services CML in Hamburg.

Even so, maritime companies, insurers, engineers, labour unions and  regulators doubt unmanned ships could be safe and cost-effective any time  soon.

While the idea of automated ships was first considered decades ago,  Rolls-Royce started developing designs last year. Marine accounts for 16 per  cent of the company's revenue, data compiled by Bloomberg show. Descended from  the luxury car brand now operated by Bayerische Motoren Werke AG, Rolls-Royce  also makes plane engines and turbines.

The company's schematics show vessels loaded with containers from front to  back, without the bridge structure where the crew lives. By replacing the bridge - along with the other systems that support the crew, such as electricity, air  conditioning, water and sewage - with more cargo, ships can cut costs and boost  revenue, Levander said. The ships would be five per cent lighter before loading  cargo and would burn 12 per cent to 15 per cent less fuel, he said.

Crew costs of $3,299 a day account for about 44 per cent of total operating  expenses for a large container ship, according to Moore Stephens LLP, an  industry accountant and consultant.

The potential savings don't justify the investments that would be needed to  make unmanned ships safe, said Tor Svensen, chief executive officer of maritime  for DNV GL, the largest company certifying vessels for safety standards.

"I don't think personally that there's a huge cost-benefit in unmanned ships  today, but technologically it's possible," Svensen said. "My prediction is that  it's not coming in the foreseeable future."

The International Transport Workers' Federation, the union representing about  600,000 of the world's more than one million seafarers, is opposed.

"It cannot and will never replace the eyes, ears and thought processes of  professional seafarers," Dave Heindel, chairman of the ITF's seafarers' section  in London, said. "The human element is one of the first lines of defence in the  event of machinery failure and the kind of unexpected and sudden changes of  conditions in which the world's seas specialize. The dangers posed to the  environment by unmanned vessels are too easily imagined."