BW Gas Ltd., the world’s biggest shipper of liquefied petroleum gas, idled four tankers because rates plunged so low that each vessel was losing the company about $25,000 a day.

The Berge Racine will idle until the end of the year, when it will be given to new owners, Andreas Sohmen-Pao, chief executive officer of parent company BW Group, said by phone, confirming a note sent to clients. Three other carriers will also stop trading until freight rates improve, he said.

“The conditions are so bad and have been bad for so long we see this as a painful but necessary decision,” Singapore- based Sohmen-Pao said. “It’s impossible to say how long we will be putting them into lay-up,” as ship deactivation is called.

Cargoes have dwindled over the past year because of delays at natural-gas projects and reduced crude output by oil- producing nations, said Geir Olafsen, chief analyst at Inge Steensland A/S, an Oslo-based shipbroker specializing in LPG. The gas is a byproduct of crude oil and natural gas output.

“Ships were built against expected new exports,” Olafsen said. “When they were delivered, that created a big overhang” because anticipated cargoes failed to materialize, he said.

Removing the crews from the idled vessels will cut daily operating costs to about $2,500 per ship, from as much as $12,000, Sohmen-Pao said. Each carrier was making about $5,000 a day in rental income and needed $30,000 to break even, he said.

The amount of LPG shipped from the Middle East, the main cargo-loading region, fell 10 percent last year from 2008 to 27.3 million metric tons, Olafsen said. Over the same period, the fleet of very large gas carriers expanded 6 percent to 140 ships, he said. (Bloomberg)