Though most of the boom is in bulk carriers, rates for container ships that carry finished products to the U.S. are up, too--as much as 30%.

FORBES: A Bubble in Bulk

The investment bill could rise yet more because of a change in the pattern of trade: in 2014 the Panama Canal opens a second lane, doubling its capacity and allowing it to carry bigger container vessels and bulk ships.

ECONOMIST: American railways

Bulk ships are the mirror image of container ships: they sail for China fully laden and return nearly empty.

ECONOMIST: Maersk orders ten colossal vessels