The Fog Signals
The brightest lighthouse in the world won't be visible in fog, smoke, or heavy rain and snow. To overcome this issue and keep ships moving safely, sound signals were used to supplement the light itself. This was crucial technology employed at thousands of light stations around the world, Kewaunee included. In fact, once the light itself was electrified, many of the jobs associated with the position of the light keeper would have been eliminated - had it not been for these vital sound signals. In cases where sound signals existed, additional keepers were often assigned to allow the rotation of duties between the keeper and his assistant(s).
Read on to learn about the evolution of these signals used at this station.
1894 - 1912: 10" Steam Whistle
North Pier Lighthouse (Old)
The first lighthouse in Kewaunee was built at the end of the North pier in 1889. From this point until November of 1894, there was no sound signal to alert sailors in poor weather.
​Several modifications were made to the light station during the 1894 season, the most crucial being the construction of a fog signal building immediately behind the 1889 lighthouse tower.
This building was used to generate steam for a 10" diameter whistle that was blown in poor visibility.
This was very common technology for the time with many light stations employing steam whistles. This 10" diameter whistle provides a single, deep-toned note that carries a fair distance over water. The larger the whistle, the deeper the tone. Steam's need to be heated and the high quantity of steam needed to blow the whistles were the two main drawbacks to this technology. According to reports to Congress, the first year the whistle was used here it sounded for 315 hours, and consumed 27 tons of coal and 2 cords of wood.
In the subsequent years, the fog signal building remained in this spot, while the pier was extended and the lights continued to be moved and reconfigured.
Hear what it sounded like!
10" Single-Note
Watch the video to hear what a similarly sized whistle sounds like when blown. Kewaunee sounded a 2 second blast of its whistle every 20 seconds in poor weather.
1912 - 1919: 10" Air Chime Whistle
South Pier Lighthouse (Current Building)
There were likely numerous factors that led the US Lighthouse Service to replace the North Pier Lighthouse and range light with the current building. Regardless of what those were, when the current fog signal building was built, it was decided the fog signal would be powered by compressed air, rather than steam. This air was provided by compressors driven by 45hp kerosene engines on the main level of the building. The air was stored in 7 massive tanks to be used as needed by the whistle.
The whistle was a 10" diameter chime whistle, meaning the single whistle sounded 3 distinct notes in a chord. The chime was a rare feature in fog whistles at the time - with most employing a single note signal.
Local newspaper articles at the time praised the new whistle, however loudly complained against the noise of the kerosene engines that powered it. For example, in 1915, the Kewaunee Enterprise ran a series of articles complaining about the noise, one of which was titled "Noisy Contraption At Pierhead Does More Harm Than Good"
The Lighthouse Service had asked the city in 1911, while this lighthouse was still under construction, if it could furnish electricity to the building. At the time however, the city light plant at the base of the pier did not have enough demand to generate electricity for the city during the daytime.
Hear what it sounded like!
10" 3-Note Chime
Watch the video to hear what a similarly sized whistle sounds like when blown. Kewaunee sounded a 2 second blast of its whistle every 20 seconds in poor weather.
1919 - 1981: Type "F" Diaphone
South Pier Lighthouse (Current Building)
When electricity was reliable enough to be available 24 hours a day, overhead power lines were run out to the lighthouse above the catwalk. In later years, the power cable was attached to the underside of the catwalk itself.
The light was electrified, and the kerosene powered air compressor was replaced with one driven by an electric motor. A gasoline engine was used to power a backup air compressor and generator for times when power did fail. The whistle was replaced with a Type F Diaphone fog horn, which is more powerful, uses air more efficiently, and provides a highly unique sound compared to other signals.
The diaphone uses a slotted piston that fits snugly inside a similarly slotted cylinder. Air drives the piston forwards and backwards very quickly, while air is forced through the slits in the cylinder and piston.
As the slits in the piston line up with the cylinder's slits, powerful puffs of air are forced through, creating sound. As many puffs of air occur at any given moment, each puff creating its own voice, the final sound that is sent from the lighthouse is far more powerful than a whistle, which only sounds from one "voice."
Type "F" Diaphone (Continued)
The feature which made the large diaphone unique and unmistakable was the "grunt" the horn made at the end of the tone. This grunt was accomplished by stopping the airflow that drove the piston inside the cylinder, while continuing to allow airflow into the "voice" of the horn. As the piston slows down once the air is cut, the pitch we hear with our ears goes down as well - creating the grunt.
The Type F Diaphone had an audible range of between 15 and 20 miles.
This fog signal was one of the most popular sound signals in the world until being rendered obsolete by better shipboard navigation such as LORAN and eventually GPS.
Hear what it was like inside the lighthouse while the horn was operating.
See how the diaphone creates its unique sound
The Radio Beacon
A Fog Signal at the Speed of Light
In March of 1930, the Kewaunee Lighthouse was one of 3 stations on Lake Michigan equipped with a new "Radio Beacon." The radio beacon was a signal transmitted from each light station, which a ship could intercept using a directional antenna. The "radiocompass" or "Radio Direction Finder" installed on the ships could be used to determine the direction the signal originated from. In this way, the ship could either steer directly towards that signal - as was the case for ships looking to enter Kewaunee Harbor. Ship captains could also use the signals from two separate stations to triangulate their position out on the lake.
With usable distances between 20 and 60 miles, this technology allowed a much higher degree of accuracy to navigation in poor weather from a much greater distance than sound signals alone.
The antenna in the photo to the right was the transmitting antenna for the radio beacon.
Not long after installation, the fog horn and radio beacon at Kewaunee were synchronized to allow the mariner to use both to determine their approximate distance from the harbor.
The radio signal and the fog signal were transmitted/sounded at the same moment.
As radio waves travel at the speed of light, they arrive aboard the ship instantly and are picked up by the radio direction finder in the pilothouse of the ship. Upon hearing the radio tone, the sailor starts a stopwatch.
Sound waves travel much slower, approximately 1 mile every 5 seconds. The sailor stops his stopwatch when the sound of the fog horn reaches him. By taking the number of seconds between the tones and dividing by 5, the sailor can estimate his approximate distance from the sound signal in miles.
This is the same principle as timing the delay between a lightning flash and the thunderclap during a storm to estimate your distance from the strike!
This technology was replaced in the 1970s by LORAN and later by GPS.
The circular antenna atop the SS Badger's pilothouse (photo left) is the directional antenna. The Radio Direction Finding unit can be seen as the gold box immediately below the antenna inside the pilothouse.
