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Minot's Ledge Light

Minot's Ledge Light is near the Cohasset Rocks about a mile off Cohasset, about 30 miles north of Duxbury. The rocks had been the scene of many shipwrecks, including 40 just between 1832 and 1841. So, in 1838, the Boston Marine Society reported that a lighthouse was needed and petitioned Congress repeatedly to build it. Congress finally appropriated the funds in 1847. The site chosen was a rock known as the Outer Minot, a 25-foot-wide stretch of rock that was exposed only at low tide on calm days and would make the lighthouse the first one in the country in a wave-washed location.

The War Department thought a stone tower could not be built in such a location so designed a 70-foot-tall tower on nine-iron pilings cemented into five-foot-deep holes drilled into the rock. The keeper’s house and lantern were built on top of these pilings, and the entire structure was far less expensive than a stone tower would have been.

The iron lighthouse on Minots Ledge went into operation on January 1, 1850. In storms, the structure reportedly swayed as much as two feet in either direction. The first keeper thought the structure so unsafe he quit after 10 months and the second keeper also expressed grave reservations about its safety. Then, on April 17, 1851, a huge storm completely destroyed the tower, killing the two assistant keepers who were manning it at the time—all that was left the next morning were a few bent pilings sticking out of the rock.

While a new lighthouse was being constructed, a lightship was anchored off Minots Ledge from 1851 to 1860. The new Minots Ledge Light, now under the U.S. Lighthouse Board’s direction, was built of interlocking granite blocks, each anchored to those above and below with massive iron dowels. Work began in July 1855. First the ledge was leveled to accommodate the seven huge granite blocks that formed the foundation. Because construction could only be done at low tide on calm days, the stones were cut and the tower erected onshore. It was then dismantled and the stones hauled to a vessel that transported them to the ledge. The last stone was laid in June 1860, creating an 89-foot tower, of which the first 40 feet was solid except for a central cistern. This base was topped by a hollow tower containing a storeroom, workspace, and living quarters (a real keeper’s house was built on Government Island in 1858. Finally, the tower was surmounted by a bronze lantern whose rooftop finial was about 108 feet above the base. A Second-Order Fresnel lens was installed in the lantern, which was first lit on November 15, 1860. At $300,000, the new Minots Ledge Lighthouse was the most expensive lighthouse built to date in the United States.

Changes to Minot's Ledge Light since that time have included the installation of a rotating mechanism for the Fresnel lens in 1894, making it a flashing light. Its flash was 1-4-3, which someone decided stood for “I love you,” so Minot's was nicknamed the “I Love You Light.” In 1947 the Coast Guard automated the light, powering it with batteries. An underwater cable was installed in 1964 and at that time the Second Order Fresnel lens was replaced with a Third Order lens. When the cable was damaged in a storm in 1971, the light was again powered by batteries until converted to solar power in 1983


A 52 Weeks of Fun Fascinating Fact about Minot's Ledge Light

This lighthouse became the first water-washed lighthouse in the history of the United States.

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  • Minot's Ledge Light
  • Boston
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