Shipowners will earn less next year and in 2012 from renting out vessels to haul goods such as coal and iron ore as the fleet expands, Arctic Securities said.

The Baltic Dry Index, a measure of commodity-shipping costs, has slid 26 percent this year, according to the Baltic Exchange in London.

At the same time, the fleet of dry-bulk vessels has swelled by 12 percent, Oslo-based investment bank Arctic said in a report dated today. Expansion will come to 8.8 percent next year and 6.1 percent in 2012, it estimated.

“Deliveries over the next years will continue pouring into the dry-bulk freight market at a pace never before seen in dry- bulk history,” analysts Martin Sommerseth Jaer and Erik Nikolai Stavseth said. “We would expect the BDI to decline as a result of a weaker market balance in 2011 and 2012.”

Dry-bulk shipping rates rose to a record in 2008 before collapsing 92 percent for the whole year, making ships ordered at the height of the market surplus to requirements.

A “discrepancy” between prices of new ships and returns owners can earn from them led to “an ordering spree during the summer months” and 58.4 million deadweight tons of new-ship capacity ordered this year in total, Arctic said.

That shows either prices for new vessels are too low or hire rates are too high, Arctic said. “Either way, we expect this window of opportunity to close as the market balance deteriorates in 2011,” Jaer and Stavseth said.

A string of three annual declines for the Baltic Index would be the gauge’s first since it slid for four years through 1998.