Lightship “N” was anchored near the shoal in 1823. One of the country’s first such vessels, “N” was built in New York, measured 72 feet in length, weighed 120 gross tons, and displayed a fixed light from each of her masts. Naval Lt. William Porter inspected the ship in 1838 and issued the following report. “Fifteen years old; very much out of order, requires thorough repairs. The cause of rot in our light-vessels can be attributed to the following causes: want of care and proper ventilation and the mephitic vapor rising from bilgewater. All causes can be obviated by the use of common windsail [ventilator] and the inverted bellows, as used on board of the vessels of the Navy, which has proved of decided benefit in expelling the noxious vapors arising in a ship’s hold.” The ship certainly didn’t provide a healthy environment for its inhabitants, but surprisingly the vessel would not be retired until 1859.

The first attempt to replace the lightship with a permanent structure was launched in 1827 when a wooden pile structure was erected on the shoal. $29,200 was spent on the project that year, but it sustained serious damage from the sea before its completion. $10,000 was spent the following year to preserve the structure, but this only delayed the demise of the lighthouse by twelve months.

Major Hartman Bache inspected the site in 1835 to determine what type of structure would be best suited for the shoal that was buffeted by the sea and, during the spring thaw, swept by ice flows. Bache’s proposal called for a stone foundation topped by an elliptical, squat lighthouse. The artificial island foundation alone would cost $84,500, and the entire project an astounding $124,000.

Bache’s superior, Colonel J. J. Albert, balked at the inordinate sum, and the project was postponed. At this same time in England, a blind engineer named Alexander Mitchell patented a screwpile foundation for constructing offshore lighthouses. He described his invention thus: “A bar of iron having at its lower extremity a broad plate or disk of metal in a spiral…on the principle of a screw, in order that it should enter the ground [sea bed] with [ease], thrusting aside any obstacles to its descent, without materially disturbing the texture of the strata it passes through, and that it should at the same time [provide] an extended base, either for resisting downward pressure or an upward strain.” The screwpile was a means of “obtaining a much greater holding power than was possible by any pile or mooring then in use.”

Brandywine Lighthouses: Screwpile and Caisson Photograph courtesy U.S. Coast Guard

Intrigued by the novel design, Albert suggested that a screwpile lighthouse be tested on Brandywine Shoal noting that if successful it would be markedly less expensive than Bache’s earlier proposal. Congress approved $30,000 in 1847 for the screwpile experiment, and construction commenced in May of 1848 under the direction of Bache and George Meade, who would later supervise the placement of screwpile lighthouses on the Florida Keys. Congress provided additional funds for the lighthouse in 1849 and 1850, bringing the total cost to $62,000. The light from the nation’s first screwpile lighthouse was exhibited on October 31, 1850, and Lightship “N” was soon relocated to replace the destroyed Minot’s Ledge Lighthouse.

Nine iron pilings served as the foundation for the Brandywine Shoal Lighthouse, but it soon was apparent that additional rows of iron pilings were needed to form an ice breaker to protect the load-bearing screwpiles from large moving ice fields. By 1858, a network of sixty-eight interconnected iron piles encircled the lighthouse. In an 1878 report, the lighthouse was described as made: “of iron, with a wooden platform, supported on screw-piles surrounding the house and forming an ice-fender. The house in shape is the frustum of a cone, and is made of cast-iron plates bolted together and lined on the inside with wood. The lantern is on top of the house. The first floor is divided into kitchen, store-room, and hall, with stairway leading to the second floor, which is divided into two sleeping-rooms and oil-room.”

In 1851, by a special act of Congress, the Brandywine Lighthouse became just the third U.S. lighthouse to be equipped with a Fresnel lens. In this case, it was a third-order lens manufactured in Paris by Henry Lepaute. The Fresnel lens had been used in Europe since the 1820’s, and mariners who had sailed abroad knew the lenses produced a far superior light. The U.S. was slow in adopting the technology mostly due to the parsimonious Stephen Pleasonton, head of the U.S. Lighthouse Service.

An ad hoc Lighthouse Board, charged with improving the country’s lighthouses, conducted an experiment at Brandywine Shoal with the Fresnel lens. The board was transported by vessel to a point fifteen miles east of Brandywine Shoal, 6.25 miles north of the Cape Henlopen Lighthouse, and 8.75 miles south of the Cape May Lighthouse. Both of these other lighthouses were coastal beacons, equipped with numerous lamps and reflectors. The board observed the three lights and concluded, without difficulty, that the Brandywine Light was more brilliant even at a greater range, than either of the first class seacoast lights. Not long thereafter, the Lighthouse Board assumed control of the Lighthouse Service from Pleasonton and started placing Fresnel lenses in all American lighthouses as quickly as possible.

After several years, there was some concern as to the condition of the iron screwpiles supporting the lighthouse, and a diver was sent down in the waters in July of 1873 to examine the pilings. The wear on the pilings was varied. Some had lost a half-inch to corrosion, while others showed no appreciable loss. Most of the pilings were bent, but none were found to be more than 15° from vertical. Overall, the foundation was found to be in good condition.

The Brandywine Lighthouse screwpile experiment had proved successful, but by the twentieth century, living conditions at the station were considered somewhat cramped compared to other offshore lights then being built. The sum of $75,000 was provided in 1911 for “rebuilding and improving the light at Brandywine Shoal on the present or adjacent site.” The decision was made to build a reinforced concrete lighthouse just fifty feet from the current light. The Annual Report of 1915 provided a detailed description of the newly completed lighthouse.

“The foundation of the structure consists of a reinforced concrete pier filled with sand, stone and concrete, 35 feet in diameter.

Fresnel lens from Brandywine Lighthouse

At the top of this pier is a reinforced concrete deck 46 feet in diameter and 24 and one half feet above mean low water. The deck supports a three-story dwelling of reinforced concrete, circular in plan, from the roof of which projects a circular watch room, which supports a third-order cylindrical helical-bar lantern whose focal place is 60 feet above high water. The main deck is covered by a veranda roof and there are galleries with railings on a level with the watch-room floor and the lantern floor. The concrete pier was constructed on shore, launched, towed out to the site, and sunk in place on a pile foundation. The pile foundations consists of 74 timber piles driven about three feet on center to a penetration of 19 feet. The heads of the piles project 1 foot above the surface of the shoal, upon which the concrete pier rests. In addition to the wooden pile foundation, the lighthouse is also fixed in position and supported by 12 reinforced concrete piles 16 inches in diameter and 34 feet long. These piles were driven into the shoal through annular pockets near the outer circumference of the caisson and the pockets around the piles filled with concrete. A layer of riprap protects the bottom about the structure.”

The third-order Fresnel lens was transferred from the old to the new lighthouse where it was first lit on the evening of October 20, 1914. The two towers stood side-by-side for a while until the superstructure of the screwpile light was torn down. The platform surrounding the old light, however, was retained, and several structures, used by the Navy in the 1940’s and 50’s, were built thereon. To form a protective harbor near the light, a protective wall of riprap, forming almost a complete circle, was placed around the lighthouse.

The Brandywine Shoal Lighthouse was the last manned station on Delaware Bay when it was automated in 1974 – an appropriate distinction for a station where the first screwpile design in this country was deployed, where one of the earliest lightships served, and where tests were conducted with the third Fresnel lens to be used in the U.S. A part of the station’s history can be visited without venturing out into Delaware Bay, as the original third-order Fresnel lens from the Brandywine Lighthouse is on display at the Tuckerton Seaport in Tuckerton, New Jersey.

References

1. "A Lighthouse For Brandywine Shoal," Wayne Wheeler, The Keeper’s Log, Summer 1999.
2. Guiding Lights of the Delaware River and Bay, Jim Gowdy and Kim Ruth, 1999.