Running the foghorn at East Brother Light Station

East Brother Light Station is located on East Brother Island in northern San Francisco Bay, and is one of the few surviving Victorian wooden lighthouses on the west coast. The lighthouse entered service in 1874, and is still in active use as an aid to navigation. The property is owned by the U.S. Coast Guard and managed by East Brother Light Station, Inc, a non-profit which operates the lighthouse as a five room Dinner, Bed & Breakfast, open to guests year-round. To learn more about staying at the lighthouse or to read about the fascinating history of the island, please visit www.ebls.org
This type of horn is known as a diaphone horn, and was popular as a lighthouse fog signal throughout much of the 20th century as its distinctive two-toned sound carried over long distances and was very easy to distinguish from ship’s foghorns. This is an example of the Improved F-Type, or F2T diaphone horn which produced an extended low-frequency “grunt” as the second tone. The equipment seen here replaced the original coal-fired steam whistle, and was in service at EBLS from approximately 1939 - 1969, when it was decommissioned and a small electric horn was installed. In spite of being out of active service for over 50 years, all of the equipment in the EBLS Fog Signal Building is fully functional after extensive renovation over more than three decades, and is used during daily demonstrations for guests as well as running various systems on the island.
Compressed air for the horn is generated by a rare working example of an Ingersoll-Rand ER-1 straight-line air compressor. The compressor is powered via belt by a circa 1939 Caterpillar D2 diesel engine.
The process of running the horn is as follows:
- The Caterpillar engine must be started by a small gasoline "Pony Motor”, which is mounted on the side of the engine and started by pull cord.
- Once the pony motor is running, the engine-to-engine clutch is engaged to start the Caterpillar, at which point the pony motor is shut off.
- Discharge valve on the compressor is opened, and a clutch is engaged to start the compressor running.
- When pressure in the receiving tanks reaches operating range of 36-40 psi, the air feed valve is opened using a chain-wheel, allowing air to flow to the horn.
- Electric timer is engaged, which triggers a three-second horn every twenty seconds. As the wheel on the timer turns, the roller riding on the wheel drops in the notches creating an electrical contact which then opens a valve in the horn creating the blast of air.
Filmed and operated by Che Rodgers, Keeper 5/2017 - 5/2019.
© Che Rodgers 2019, all rights reserved