Japan's bulk carrier builders have unexpectedly found themselves with a fresh competitive edge following unusual movements in the international currency markets.

An expected rise in US interest rates has prompted a further devaluation of the Japanese yen against the US dollar, continuing a trend that in the past 12 months has dramatically improved the earning potential of Japanese yards.

Another factor has been a strengthening Chinese yuan over the last 18 months that has left rival Chinese shipbuilders, temporarily at least, at a competitive disadvantage.