Thursday, September 26, 2013


Lewes, Delaware

Overfalls is a "lightship", meaning it was a portable lighthouse. It's a National Historic Landmark—the only one in Sussex County, Delaware.

Built in 1938, it served the East Coast for 34 years. One hundred seventeen were built. Seventeen remain extant; Seven are open to the public.

What is a lightship?

A lighthouse that floats, it serves the same function such as:
  • A light to aid navigation at night
  • A horn to warn mariners in fog
  • A radio beacon for longer range identification
Lighting the way
The Overfalls main aid to navigation was a 375 mm dual electric lantern located 57 feet above the water line. Rated at 15,000 candle power, (approximately 1,000 watts), it flashed every 3 seconds from dusk until dawn. On a clear night it could be seen for 12 miles.
The ship also had a dual diaphone fog horn with a range of 5 miles that sounded every 30 seconds in foggy weather.
A radio beacon with a range of 25 miles transmitted the call letters of the ship (NMJF) in Morse code. In foggy weather it was synchronized with the horn and broadcast every 30 seconds.

P.S. Back in the 1950-60s, Lewes was the biggest fishing port in the country by tonnage of fish caught.