Industry changes, friendships don't.

One day in 1968, when Mike Diaz was with American Export Lines, he was visited by consultants from McKinsey & Co. They were working for a ship line that was planning to move from breakbulk to containers, and they wanted to learn how AEL had made the switch on two of its services.

Diaz shared details about his line's experience. The consultants thanked him and presumably used the information to advise their client, a Danish company named A.P. Moller, whose Maersk Sealand now is the world's largest container line.

Thirty-five years later, Diaz laughs about the episode. "Maybe I shouldn't have talked to the guys from McKinsey," he says. "Then we might have kept …