A hundred years ago today, May 1, 1921, navigation in New York Harbor became a safer proposition thanks to being equipped with a system of radio warning signals aiding navigation. Lighthouses and light ships had long been present, but they were of very limited usefulness in foggy conditions. Therefore, the lighthouse at Sea Girt, NJ, as well as the light ships Ambrose and Fire Island were equipped with powerful radio beacons.

Official notices had been made to mariners, and many vessels were already equipped with radio compasses in the form of a rotatable loop attached to the receiver. The beacon would identify in Morse, and the bearing could be fixed to within one degree.

Radio had been in operation on the Fire Island for some time, as we recounted previously. That ship was equipped with both a wireless transmitter and a bell. By measuring the time between reception of the radio signal and the bell, distance could be accurately measured.  The Sea Girt lighthouse, however, was the first land-based radio fog beacon in the U.S.

This description of the system appeared in the New York Tribune, May 8, 1921.