With the demise of British seamen, whose numbers have fallen from 70,000 to 30,000 in the last decade alone, there has been an influx of foreign mariners from south-east Asia and Eastern Europe who do not speak English.
Now the European Union is putting pounds 300,000 into a research project which is designed to come up with a single working language, probably based on English, and which all seamen can understand.
The influx of foreign languages has created tensions among the crews on ships where there may now be up to 30 different languages spoken.
There have also been mix-ups and misunderstandings which have led to accidents and deaths.
Incidents have included the desperate search for a Chinese waiter in Wales who spoke the same language as the crew of a salvage tug that was in Milford Haven when the Sea Empress ran aground.
As part of the work, researchers from the University of Wales, in Cardiff, are using tape recorders to capture the communications, or the lack of them, on the bridges of selected ships, where there may be a British or a Dutch captain, a Filipino chief officer, a Chinese second mate and an African third officer, all working alongside each other.
"Gradual evolution has changed the composition of seafarers, and they are now predominantly from countries where English is not the first language," said Professor Alastair Couper who is co-ordinating the research.
"They can have different versions of English too, and the same words can have different meanings. You can get all kinds of problems and many tensions and anxieties," he said.
The team are looking at the extent of language diversity, the use of sign language, and are compiling a report on those accidents where communication problems may have been involved.
"The problem has been highlighted by a number of incidents, including the Sea Empress disaster," Professor Couper said.
"Language was a major factor, for example, in the fire on board a Baltic ferry where 100 people died.
The opportunities for misunderstandings are very great and a lot of casualties have taken place as a consequence," he said.
As well as producing a pilot syllabus for the teaching of maritime English and guidelines for avoiding misunderstandings, the researchers also intend to come up with methods of managing what are described as cross-cultural tensions.