ROTTERDAM -- Shipping companies could save a fortune in training costs and improve safety at sea by using "virtual reality" navigation simulators, according to experts.


Ships' officers must currently spend long and costly periods at sea while training for their master's certificate.


But computer simulators, which recreate almost every aspect of a ship's bridge -- even to the extent of bringing on possible sea-sickness -- can reduce this training time dramatically while offering valuable experience of rare emergency conditions.


"The potential savings for fleet operators are huge," said Tjakko Bouwman, director of the Royal Dutch Shipowners' Association. "We think the compulsory sailing time for a trainee can be brought down if navigation simulators are used."


Simulators were first developed by defense companies in the 1970s, and although they are now widely used for flight training they have only recently been adapted for sea navigation.


Simulators for maritime training use high-definition computer technology which combines three-dimensional graphics projected onto wrap-around screens with sound and movement.


The U.S. company FlightSafety International, which has just installed a navigation training system for the Dutch port of Rotterdam, has also made its latest system interactive so that students can react to each other while learning. The 20 million guilder ($11.43 million) Rotterdam unit can simulate the behavior of up to five vessels and port controllers anywhere in the world and is so realistic its owners are indeed expecting cases of sea-sickness.


"The problem in the past for ships has always been that simulators were always single. In a big harbor a large vessel may need at least four tugboats as well as a pilot and all of them need to work together," said Louis Kroezen, of MarineSafety Rotterdam, a joint venture of FlightSafety and Rotterdam City.


"Here we can simulate any ship of any size in any port, even ports that are still in their design stage. We can simulate rain, storm or fog ... and mimic chemical disaster or fire."


There are still only a handful of sophisticated simulators available to shipping companies around the world and none of them is as advanced as the Rotterdam system. They are also expensive -- Rotterdam charges 500 guilders per hour excluding the use of a trainer. But experts say it is money well spent.


Fred Bloot, technical officer at the Dutch Transport Ministry, says sea training is enormously costly and is one of the main reasons for the growing shortage of ships' officers with internationally recognized qualifications.


"Ships' officers must do four years of training ... one of which must be at sea," he said. "If you could reduce the at-sea training period for a master's certificate by just three months, it would save the industry tens of millions of guilders."


Roger Kohn, spokesman for the International Maritime Organization, said 80 percent of accidents at sea are thought to be due to human error and the only way to reduce that toll is with training.