Mile Rocks Light
Mile Rocks Lighthouse with helicopter landing on the top
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 San Francisco
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| Location | offshore Lands End San Francisco California United States |
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| Coordinates | 37°47′34″N 122°30′37″W / 37.79278°N 122.51028°WCoordinates: 37°47′34″N 122°30′37″W / 37.79278°N 122.51028°W |
| Year first constructed | 1906 (first) |
| Year first lit | 1966 (current rebuilt) |
| Automated | 1966 |
| Foundation | massive reinforced concrete enclosed with steel plates basement |
| Construction | steel tower |
| Tower shape | cylindrical tower with aerobeacon and helipad on the top (current) 3-stage cylindrical tower with balcony and lantern (first) |
| Markings / pattern | white and red horizontal bands tower (current) white tower |
| Focal height | 49 feet (15 m) |
| Original lens | 3rd order Fresnel lens |
| Current lens | aerobeacon |
| Light source | solar power |
| Range | 15 nautical mile 
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| Characteristic | Fl W 5s. |
| Fog signal | blast every 30s. continuously |
| Admiralty number | G4054 |
| ARLHS number | USA-496 |
| USCG number | 6-0365 |
| Managing agent |
United States Coast Guard |
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United States Coast Guard
Mile Rocks Lighthouse is located on a rock about 1 mile (1.6 km) southwest of the Golden Gate Bridge, off of Lands End in San Francisco, California. It was completed in 1906, replacing a nearby bell buoy. The tower of the lighthouse was removed in 1966, the top converted into a landing pad for helicopters, and the light automated. The lighthouse was at one time painted with alternating red and white rings, but as of 2017, the lighthouse is painted plain white.
In 1889, the United States Lighthouse Service placed a bell buoy near the rocks. However, the strong currents in the area would pull the buoy beneath the surface of the water and set it adrift. The lighthouse was completed in 1906 after considerable difficulty caused by the heavy seas and strong currents occurring at this point. The rock upon which the lighthouse is built measured only 40 by 30 feet (12.2 by 9.1 m) at high water. The base of the tower is a large block of concrete protected by steel plating. Steel and concrete in the foundation alone weighed 1,500 tons. The superstructure is of steel, and houses the fog signal apparatus and the quarters for the keepers, with the lantern above.
It was on this rock that the SS City of Rio de Janeiro was wrecked shortly before the building of the lighthouse. One hundred and twenty-eight persons, of 209 aboard, lost their lives when the City of Rio de Janeiro sank on February 2, 1901.
The original third order Fresnel lens was transferred to the Old Point Loma lighthouse in San Diego. In 1966, all of the tower was removed and only the first story was left, and the light automated. The top of the first story is now a landing pad for helicopters.
Original Light – U.S. Coast Guard Archive
Mile Rocks lighthouse, with Point Bonita and Marin headlands in distance
The lighthouse after modifications
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Wikipedia