Four years after the Coast Guard began an effort to replace nearly its entire fleet of ships, planes and helicopters, the modernization program heralded as a model of government innovation is foundering. The initial venture — converting rusting 110-foot patrol boats, the workhorses of the Coast Guard, into more versatile 123-foot cutters — has been canceled after hull cracks and engine failures made the first eight boats unseaworthy. Plans to build a new class of 147-foot ships with an innovative hull have been halted after the design was found to be flawed. Full Story