Historic postcard of American Shoal.

Beacon B as depicted near American Shoal Lighthouse in a 1910 postcard. Click image for credit and larger view.

History of Beacons

A Visual Positioning System

Despite 19th century efforts to improve maritime commerce, poor positioning accuracy still contributed to dozens of vessels grounding in the Florida Keys each year.  The U.S. Coast Survey was tasked with developing navigational aids in the Florida Keys, including a series of unlighted reef beacons that visually warned ships of their proximity to the reef. Before modern, satellite-based Global Positioning Systems (GPS) were in place to guide boaters, day beacons were a visual positioning system that helped mariners confirm their position on charts.

The first beacons in the Keys were primitive “screw pile” beacons installed in two to four feet of water at American Shoal, East Washerwoman, and Caesar Creek. The nine-foot long iron piles driven into the seafloor held 30 to 40-foot long mangrove wood posts. The posts were topped with a black colored barrel that could be seen with the naked eye from a distance of two to three miles and up to six miles using a spyglass.

Beacon and lighthouse.

The shaft from unlit Beacon B is still visible above the water near the historic American Shoal lighthouse. Click image for credit and larger view.

Totten Beacons

By 1853, construction began on more permanent markers, labeled alphabetically from "A" through "P". These would become known as the “Totten Beacons” after Lieutenant James B. Totten, the U.S. Army Assistant to the Coast Survey who oversaw their construction. Totten reported to his superiors that he had installed 14 of the 15 planned beacons by July 1855.

Each beacon consisted of several parts. At its base, a nine-foot long, nine-inch diameter cast iron screw pile was driven into the reef. The screw pile’s top end was a four-foot hollow pipe to accept the beacon’s vertical shaft. For ease of transportation, the beacon’s mast was comprised of three sections, starting with a 14-foot cast-iron base inserted into a screw pile. The base was then bolted to a 10-foot long cast iron mid-section via a set of collars. The mid-section, in turn, was bolted to a 16-foot long wrought iron upper spindle. The shaft of the upper spindle tapered from a 7.25-inch diameter at its base to two inches in diameter at the top. The lettered marker was mounted on two powerful hinges at the junction of the second section and the spindle, creating a vane that held the wrought iron letter inside of a six-foot frame. The spindle’s top was crowned with a lattice-work iron cylinder hoop, six feet high and 2.5 feet in diameter to give it extra visibility. Each beacon was painted in various patterns of black, white, and red, so that no two adjacent beacons had the same colors on like parts.

Inset view from an early Totten Beacon drawing showing the use of a letter to mark the reef. Click for larger image and credit.

Totten Beacon diagram. Click image for credit and larger view.

The Remaining Legacy

Following Totten’s work, storms and hurricanes battered the beacons. Some remained standing for only a few years, while others lasted decades. The U. S. Lighthouse Board took over responsibility for the beacon’s maintenance and by the 1870s had developed more substantial beacons that used stakes, tie rods, and turnbuckles to provided additional support to the beacon’s mast.

Some of the new beacons replaced the single letter vane with a tri-vane design that made the letter visible from more angles. These newer style beacons also used screw piles that had a disc-shaped base similar to the screw piles used on several of the lighthouses installed on the Florida Keys reefs. Historical research suggests that the beacons were maintained until the 1920s, serving an important role protecting lives and property.

Single vane beacon design. Instead of a number, Totten Beacons contained letters from A to P. Click image for credit and larger view.

Tri-vane beacon design, in which the letter was visible from more angles. Click image for credit and larger view.



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