San Francisco’s huge sand bar, rocky shores, narrow entrance, swift currents, high winds and submerged rocks can make entering the San Francisco Bay a treacherous undertaking, even today. But a ship captain’s greatest source of concern when sailing to the City is fog: the low pressure fog that can bring visibility down to zero[1]. Shipwrecks were common in San Francisco’s early years. It is estimated that there have been about 400 shipwrecks. My great grandfather, William CTS Filmer[2], a former ship captain who was very proud that he’d never sunk a ship, was San Francisco’s Harbor Master in the 1940s and often went out on tug boats to help navigate ships to shore.
In 1849 when the Gold Rush brought settlers to the San Francisco in droves, the only way to give a ship captain his bearing in low fog were bonfires set at the tip of Lands End[3]. Ships steered to the left of those bonfires to avoid the San Francisco sandbar located quite a ways out from Ocean Beach[4]. The cliffs at the point were whitewashed to make the landmark clear. The first fog signals, manually-operated bells, were placed at critical sites, including Alcatraz[5], Fort Point[6], Angel Island[7], Mile Rock, Blossom Rock[8] and Yerba Buena Island. In 1878 these bells were replaced with steam whistles. In the early 1900s steam whistles were replaced with diaphone horns that had three sleeves of brass that vibrated in a chamber via steam-powered air compression. They were two-toned, making the iconic “BeeeOhhh” sound. Invented in 1929, diaphragm horns replaced diaphone horns. Diaphragm horns, like the one located today on the Golden Gate Bridge[9], have two metal discs in the horn that emit a solid blast. They produce similar levels of volume to the diaphone horns but require smaller and much less powerful air compressors. Today, all of the diaphone horns that were located throughout the San Francisco Bay have been replaced with audible electronic beeping signals.
In 1854 the first lighthouse on the West Coast was placed on the southwest corner of Alcatraz, and a bell was placed on the southeastern tip of the island. In 1909 the original 50 foot lighthouse, which had been severely damaged in the 1906 Earthquake and Fires[10], was replaced with an 84 foot concrete tower that is still in operation today, though it became automated in 1963.
Shortly after the lighthouse and fog bell were activated on Alcatraz, a lantern and fog bell were installed on the roof Fort Point. The lantern operated from 1864-1934 and still remains today.
In 1856 a light house was built at Point Bonita at the northern point of the San Francisco Bay. It was first built on a 300 foot ridge, but in 1877 was moved closer to the tip of the point. It is maintained today by the US Coast Guard and open to the public on Saturday, Sunday and Monday afternoons. For the first two years of operation, a cannon would fire every 30 minutes when the fog was low. At one point, after three consecutive days of fog, the Army sergeant assigned to this post threatened to quit. He was given an assistant, but even so, 1,390 rounds were fired the first year, 1,582 rounds the second. Seen as too burdensome, the cannon was discontinued and removed, though the lighthouse remained.
In 1859, after 23 people died when the Lucas, a three-masted passenger ship, crashed off the Farallon Islands[11], a fog whistle was installed there using a naturally formed blow hole to accommodate a fog whistle. It turned out to be incredibly unpredictable: if there were no swells on a becalmed foggy day, the whistle made no sound. In 1880 it was replaced with a steam powered siren.
In 1886 the Point Knox Lighthouse on Angel Island was erected. It was a single-story wood shack. A second story was added in 1915. The Coast guard burned the building in 1963 and installed an electronic light beacon at that location. Concurrent with the lighthouse, a fog bell was installed on the other side of the island.
In 1901 the steamship Rio de Janeiro struck the reef off of northern side of Lands End as it was returning from Hong Kong. Of the 220 passengers, only 79 survived: it would be the deadliest shipwreck in San Francisco history. As a result, the Mile Rock lighthouse was installed in 1906. It was considered one of the most spectacular rock lighthouses in the world. In 1966 the lighthouse was dismantled and converted into a helicopter pad. Today just the skeleton of the platform remains. It still retains an electronic sound signal.
In 1936 the San Francisco Bay had 51 diaphones, whistles, bells and sirens. When the Golden Gate Bridge was completed in 1939, diaphragm horns were installed on the south tower and under the roadway at midspan. The south tower (one 2-second blast every 30 seconds) guides incoming ships while the midspan horns (two short blasts) guides outgoing ships. It is still manually maintained whenever the fog dips below the span. In a typical year, the fog horns average about 900 hours. In 2013 the fog horn on the south tower got stuck in the “on” position, blasting continually from 2 am – 3:15 am.
Growing up in the Sunset in the 1940s and 50s my mother Anne remembers being able to hear the fog horns on the Farallon Islands and at Mile Rock – they were that loud. The sounds they made were deep and mournful, but like most San Franciscans who grew up here, Anne found the sound comforting.
In 1960 the Angelo Petri, the world’s largest wine tanker, sank just outside San Francisco’s Golden Gate Bridge. It was carrying 2.3 million gallons of wine and vegetable oil. As a result of this shipwreck, outdated fog horns were replaced with electronic sound signals. Today radar, sonar and depth finders make fog signals obsolete, but ships, fishing boats and recreational sailors still use the lighthouses and sound signals to navigate water hazards when the fog rolls in.
[1] Karl the Fog: https://thesanfranciscophoenix.com/?p=3950
[2] William CTS Filmer: https://thesanfranciscophoenix.com/?p=4643
[3] Lands End: story coming March 20th
[4] Ocean Beach: https://thesanfranciscophoenix.com/?p=5243
[5] Alcatraz: https://thesanfranciscophoenix.com/?p=3344
[6] Fort Point: https://thesanfranciscophoenix.com/?p=3968
[7] Angel Island: https://thesanfranciscophoenix.com/?p=3487
[8] Blossom Rock: see story coming December 27th
[9] Golden Gate Bridge: https://thesanfranciscophoenix.com/?p=4916
[10] 1906 Earthquake and Fires: https://thesanfranciscophoenix.com/?p=2849
[11] Farallon Islands: https://thesanfranciscophoenix.com/?p=4818
