The surplus of supertankers competing to ship 2 million barrel cargoes of Middle East crude oil expanded as ship demand slowed.

There are about 18 percent more very large crude carriers, or VLCCs, for hire over the next 30 days than there are probable cargoes, according to the median estimate of five shipbrokers and one owner surveyed by Bloomberg News today. In the previous survey two weeks ago, the surplus was 11 percent.

Oil companies are delaying booking the ships they need to force rental rates lower, Per Mansson, managing director of Nor Ocean Stockholm AB, said by e-mail. “The market started fading a bit in the days before New Year,” he said. Oil companies “will probably keep the cargoes away from the market as long as possible.”

Charter fees on the Saudi Arabia to Japan costs voyage jumped 19 percent to 70.08 Worldscale points a day today, according to the Baltic Exchange, yielding owners daily returns of $28,504 a day.

Average charter rates on the industry benchmark route plunged 69 percent to 41.74 Worldscale points last year as the Organization of Petroleum Exporting Countries made the deepest output cuts ever in response to the worst global recession since World War II.

That equated to average earnings of $23,130 a day for owners, according to the bourse. Frontline Ltd., the biggest operator of the ships, said in November it needs $32,900 a day to break even on its vessels.

Of the six respondents, three people said the supply of ships increased relative to demand, two said it shrank and one said it stayed the same.

Worldscale points are a percentage of a nominal rate, or flat rate, for more than 320,000 specific routes. Flat rates for every voyage, quoted in US dollars a ton, are revised annually by the Worldscale Association in London to reflect changing fuel costs, port tariffs and exchange rates.