|Gravelly Shoal Light||Seeing The Light|
Perhaps as a result of its exposed location, or as a result of its keeper's dwelling being one of the few of wooden frame construction on any of the Great Lakes, the station was a constant source of maintenance problems, and was not surprisingly one of the first to be automated through the installation of an acetylene illumination system in 1900. At this time an occulting white Pintsch gas buoy was also placed at the southeastern end of Gravelly Shoal to better mark the western edge of the passage between the shoal and Big Charity Island.
As a result of the combination of increasing vessel size, improvements in offshore light construction and the growing adoption of radio direction finding equipment, it became plain in the late 1930's that the old Charity light and the gas buoy on Gravelly Shoal had outlived their usefulness, and consideration turned to the construction of a state-of-the-art offshore aid to navigation at the eastern end of Gravelly Shoal to better mark the deeper water of the passage. United States Lighthouse Service engineers F. P. Dillon and W. G. Will were tasked with the design of the structure, and resurrected their design previously used with great success on Lake Erie at both Conneaut and Huron in 1935.
As a sign of the times, construction of the new light on Gravelly Shoal was incorporated as part of President Franklin Delano Roosevelt's Public Works Administration, designed to "put America back to work," and as such was built under PWA project No. 56. Bids for the actual construction work were advertised out of the Detroit depot, with 32-year-old John C. Meagher of Bay City's bid of $75,000 winning him the contract. The $24,000 contract for the fabrication of the steel tower itself was awarded to the Wickes Boiler Company, the world-renowned boiler engineering and fabricator, located in Saginaw.
Meagher's flotilla, consisting of the crew boat Tipperary and the old wooden work barge Marquis Roen, set out for Gravelly Shoal on a calm April 12th, 1939, and after using a sextant to locate the specified location for the light (44°03.0'N., 83°32.3'W.), turned to the task of driving five wire-wrapped pile clusters deep into the bottom in 24 ½ feet of water. After the installation of waterproof exterior forms and the removal of the water with pumps, the concrete 50-foot diameter pier itself was poured, along with its integral basement service rooms.
Conditions at the site continued atypically calm through April and May, with only two days lost due to inclement weather conditions. However, things took a turn for the worse in July, when the water became so rough that in one thirty day stretch the crew was only able to tie-up at the pier on one single occasion. By August, conditions began to clear, and with work on the pier complete, the Marquis Roen arrived at the Wickes Boiler Company dock, and the 61-foot tall steel tower was hoisted onto the barge's deck for the trip out to the shoal. Tied-up alongside the circular pier, a large wooden shear leg was erected on the barge's deck, and the 25-ton tower carefully lifted from the deck and lowered inch-by-inch onto its locating bolts at the center of the concrete pier.
As the project neared completion, Meagher speculated that the thickness of the pier at the waterline was insufficient to withstand Huron's heavy wither ice crush. Convinced of his calculations, he recommended the thickness of the pier at the side walls be increased by seven feet to better protect the piers structural integrity, and provided a quotation of $7,000 to perform the additional work. However, the Coast Guard, to whom responsibility for the nation's aids to navigation had been transferred that same year, disagreed, and accepted the station as constructed, placing it into service in October, 1939.
Designed as a completely automated electrified station, the Gravelly Shoal Light came under the control and maintenance of Coast Guard Station Tawas. The station's 375 mm light was equipped with a 15,000 candlepower, 120 volt electric lamp with current supplied by way of a submarine cable laid across the surface of the shoal from Point Lookout. The light's 75-foot focal plane allowed the characteristic 1-second flash every 5 seconds to be seen from a distance of 16 miles. A standby 110 candlepower acetylene light with a half second flash every three seconds was also installed, and was designed to activate automatically whenever electrical power at the station was lost For operation in thick weather, the station was also equipped with twin two-tone #3 diaphones, emitting a characteristic 30-second cycle consisting of a 3-second blast followed by 27 seconds of silence. The diaphones received their supply of compressed air from twin electrically driven compressors located in the utility rooms deep within the pier.
Fifteen years after the station's completion, the Coast Guard determined that winter ice floes were placing undue stress on the pier side walls, and as the original contractor, Meagher was approached to add seven feet of concrete to strengthen the pier sides. Meagher was more than happy to make the modification at a cost of $54,000, some $47,000 more than the amount he had quoted fifteen years previously!
At some thereafter, a large steel tower
was erected atop the station for a radiobeacon transmitter. The 1953
Coast Guard Light List indicating that the signal transmitted at 296
kilocycles, and emitted a group of 0.5 -second dashes for 15.5 seconds,
followed by 14.5 seconds of silence. As of 2001, both the light and
radiobeacon still serve as active aids to navigation.