 The new law required that all passenger-carrying ocean vessels of any nationality leaving a U.S. port had to be fitted with efficient radio apparatus when carrying 50 or more passengers and crew.This equipment had to be capable of transmitting messages to other systems over a distance of at least 100 miles (160 km), and under the supervision of a skilled operator.One exemption was that the law did not apply to "steamers plying only between ports less than 200 miles (320 km) apart".