Maersk (MAERSKB) Line’s Triple-E class container supership will be the biggest vessel afloat when it enters service in July, with a capacity of 18,000 20-foot boxes. Unfortunately for the world’s largest shipping line, the $190 million Triple-E is too big for any port in the Americas and can’t make it through the Panama Canal. That restricts it to an Asia-Europe market, where growth in cargo demand is weaker than forecast when Maersk ordered 20 of the megaships two years ago from Daewoo Shipbuilding & Marine Engineering (042660) for a total of $3.8 billion.