The Radiobeacon System Great Lakes map
Thanks to a gift from Nancy Burgess, and her dad, Robert Hoth, we now have a 1950 ‘United States Coast Guard Radiobeacon System Great Lakes’ map to add to our collections.
The Plum Island Station was one of the synchronized distance-finding commercial radio communications stations (Class C, 20-mile range) that served the bulk-carriers (iron ore, coal, petroleum, cement and limestone) boats and freighters on the Great Lakes. It was established May 3, 1940 and discontinued in 1982. The Plum Island signature code was 'UM', as in "Uniform Mike' a phonetic alphabet used to clearly spell letters in radio communication.
The radio beacon system was a critical part of maritime safety and communication infrastructure evolved from early Morse Code until the rise of satellite-based systems (GPS) in the late 20th century.
The radio beacons were located at entrances to heavily travelled harbors, at coastal areas and at other key locations and landmarks to transmit radio signals for use by marine navigators. They transmitted signals by radio in all directions much the same as lighthouses do. Each radio beacon was identified by the unique characteristics of the transmitted code much like the visual signal sequences of lighthouses and considered an aid to navigation. Radio beacons were located such that bearings from two or more could be obtained for position fixes in most areas on the Great Lakes.
The Plum Island radio beacon broadcast a ‘___’ distinct signal repeatedly for 60 seconds with 120 seconds silent. All radio beacons operated during fog or low visibility, and during one of two 10-minute periods out of each hour in clear weather. The Plum 10-minute period of each of clear weather was assigned a time of 5 to 11.
I had the opportunity to chat with former Plum Island Station Coastie, David Robb (1965), and learned quite a bit about the radio beacon on the island. When Robb was stationed on Plum, the beacon’s equipment was in the fog signal building’s watch shack, which was added to the front section of the building in 1955.
The crew would also keep an eye on the range lights so they could quickly change the bulbs out, if needed. In his time the Fresnel lens was lit by a system of 4 chandelier-sized bulbs that rotated when a new bulb would burn out. When the fourth lightbulb burnt out, the crew member would run from the fog signal building and up the range light stairs to quickly change out the bulbs as soon as possible.
An automatic identification finder (ADF) was located on board ships, somewhat like a radio, that could pick up these unique radio frequencies. When the ADF was rotated through 360 degrees, it would pick up the Morse codes. Once the strongest signal was found, the mariner would read the compass and plot a series of direction lines to find out where the boat was located in the water. Each station would broadcast 24 hours at a unique frequency at a specified time with a code that identified the station.
The Plum Island Rear Range Light’s latitude / longitudinal position is 45-18-13.597N / 086-57-29.447W and the Front Range Light’s position is 45-18-13.597N / 086-57-17.935W degrees and depending on the plotted location, they would know how close they were to the island inspite of the weather. For example, when approaching the Door from the south on a foggy day, the radio beacon signal would coincide with the fog signal. Robb said that he could set his stopwatch at the moment he heard the beep of the radio beacon and a few seconds later he would hear the actual foghorn blast. The Plum Island foghorn’s signature was a 3-second blast with 17 seconds of silence. This was distinct from Pilot Island’s signal which was a 5-second blast followed by 30 seconds of silence.
The crews’ quarters housed an auxiliary radio system with an AM radio (FM was just being introduced) and the ability for communication from the fog signal to the station. The main radio was in the watch shack, but the auxiliary radio was used during search and rescue operations so the chief could stay in communication with the boat.
Later a teletype machine was added.
Note: A special thanks to Master Captain David Robb, who taught me more about the Coast Guard,, boats and radio transmissions than I could absorb in one sitting and won't soon forget!
Also, a special thanks to Nancy Burgess who knew that others needed to learn about the importance of the map that her father kept all these years.
Comments