Chatham Light has swept this shoreline for nearly 150 years. Help us keep it that way.

In July 2026, the Coast Guard replaced Chatham Light’s longtime rotating DCB-224 beacon with a new LED beacon.

The difference is readily visible. The former light produced a broad, powerful rotating sweep across the waters around Chatham and offshore. The new LED produces a far lower-intensity beam, changing the near-shore coverage, the visible sweep and the familiar loom of Chatham Light.

That’s why we’re asking the Coast Guard to take another look—not because LED technology is bad, but because we believe there may be better ways to deliver the navigational performance Chatham Light needs.

Not by itself. LED describes the light source; it does not by itself establish the beam’s navigational performance. LEDs can produce light using fewer watts, but electrical efficiency is not the same as luminous intensity or effective navigational performance.

In fact, the prior DCB-224 beam had the narrower vertical divergence—approximately 1.5–2 degrees, compared with roughly 3 degrees for the new single-tier MBR300R LED. Vertical divergence is also different from the horizontal width of the beam as it sweeps around the horizon. A supposedly narrower LED beam therefore does not explain the loss of the near-shore sweep or make the new light equivalent offshore.

The central difference is luminous intensity, measured in candela. The prior beacon was rated at approximately 2.8 million candela; the installed LED configuration is approximately 78,000 candela. That is less than 3% of the prior beacon’s intensity.

Candela already measures how strongly a light is projected in a given direction. Greater intensity leaves more light available to reach a mariner after distance, fog, haze, moisture, rain or snow attenuates and scatters the beam. Those degraded-visibility conditions are precisely when a major coastal light’s conspicuity and loom matter most.

Offshore, lower intensity affects the distance and conditions in which the light can be detected conspicuously and the margin available when visibility deteriorates. Near shore, it weakens both the direct flash and the scattered loom that made Chatham Light a readily recognizable reference around the harbor approaches and shifting shoals. These differences raise the same concrete safety question in both settings: does the new configuration provide mariners with an adequate detection and conspicuity margin in real marine conditions?

Chatham Light carried a published nominal range of 24 nautical miles for decades. The Coast Guard has now changed that listing to 14 nautical miles. Seeing the new light once at a long distance in clear air does not show that it provides the same intensity, conspicuity or performance in real marine conditions. The relevant question is not whether LED technology can be effective—it can—but whether this particular installation provides the offshore and near-shore performance mariners need from Chatham Light.

Yes. On August 19, 2026, the Coast Guard updated the Light List entry for Chatham Light from 24 nautical miles to 14 nautical miles. That is a reduction of 10 nautical miles, or approximately 42%, from a range that had been published for decades.

The Coast Guard has explained the change in relation to the commercial shipping lanes and said it does not consider the revised range to present a safety issue. NOAA’s current electronic-chart data confirm that substantial portions of the offshore traffic separation scheme lie at or beyond the new 14-nautical-mile nominal range.

But the exact location of a lane boundary is not the central issue. Nominal range is a standardized rating based on 10-nautical-mile meteorological visibility; it is not a guarantee of detection in the fog, haze, moisture, rain, snow and rough weather regularly encountered off Chatham. With the traffic lanes already near the light’s nominal limit, the important safety question is whether the new light has enough intensity and conspicuity to provide a prudent margin when real conditions are worse than the rating condition.

The shipping channel is an important consideration, but it is not the only water or group of mariners served by Chatham Light. Local commercial fishermen, recreational boaters and smaller vessels also operate around Chatham’s harbor approaches, shifting shoals and near-shore waters. We appreciate the Coast Guard’s explanation and recognize its responsibility for setting federal aid-to-navigation requirements.

When the LED beacon was installed, Coast Guard personnel said it was expected to provide “the same, if not better, visibility offshore,” and reported clear-air sightings beyond 25 nautical miles. Those observations and the new 14 NM listing provide important context, while the light’s physical intensity, degraded-visibility performance, near-shore conspicuity and recognizable rotating sweep remain appropriate subjects for collaborative evaluation.

We see this as a reason for continued constructive discussion. The goal is to understand the revised specification and work with the Coast Guard to ensure Chatham Light serves the full navigational context around Chatham. Read the full update.

Because Chatham Light sits above unusually challenging water.

The U.S. Coast Pilot, NOAA’s official coastal navigation publication, describes constantly shifting shoals at the entrance to Chatham Harbor, advises extreme caution, and describes the difficult waters and shoals extending toward Monomoy. These are the waters immediately below and around Chatham Light.

The former powerful rotating beam provided a conspicuous visual reference across these near-shore waters. Its sweep also cast light across the outer bar and breaking water, giving mariners another indication of surf and sea conditions.

The new light’s far lower intensity weakens the direct flash and eliminates much of the scattered loom, making it a less conspicuous and therefore less effective safety reference for mariners. That difference may become more apparent as daylight shortens and fall conditions change. It raises a straightforward question: can we restore useful near-shore coverage while still providing strong offshore performance?

We think we can.

For decades, the U.S. Coast Guard Light List published Chatham Light as a 24-nautical-mile light, with its familiar characteristic of two white flashes every 10 seconds—Fl (2) W 10s. On August 19, 2026, the Coast Guard changed the published nominal range to 14 nautical miles, a reduction of approximately 42%.

The U.S. Coast Pilot, NOAA’s official guide to coastal navigation, reinforces Chatham Light’s navigational role by identifying the light in describing the surrounding approaches, shoals and waters. Together, the Light List and Coast Pilot provide the navigational context for what Chatham Light is expected to do.

When the new LED beacon was installed, Station Chatham’s commanding officer said it was expected to provide “the same, if not better, visibility offshore.” Coast Guard personnel also noted that the new beacon could be seen more than 25 nautical miles away.

The Coast Guard has explained the new range in relation to the commercial shipping lanes, and NOAA’s chart data confirm that substantial portions of the traffic separation scheme lie at or beyond 14 nautical miles from Chatham Light. The concern is not a precise lane boundary. It is whether a light whose nominal rating is already near the shipping lanes provides a prudent safety margin in the fog, haze, moisture, rain, snow and rough weather regularly encountered off Chatham. That is relevant context, alongside the needs of local commercial fishermen, recreational boaters and smaller vessels using the near-shore waters.

A replacement should provide offshore intensity and conspicuity with an appropriate safety margin in degraded visibility, while also restoring a useful near-shore reference. Range, intensity and beam coverage all matter. So does the strong visual presence—or loom—that helps make a major coastal light readily recognizable in real marine conditions.

The goal is a light that provides the near-shore and offshore navigational performance mariners expect from Chatham Light.

Chatham Light’s published characteristic is Fl (2) W 10s—two white flashes every ten seconds. That distinctive pattern helps mariners identify Chatham Light.

With a rotating beacon, the beam sweeps past the observer rather than shining continuously in one direction. Horizontal beam width, rotational speed, flash duration and intensity therefore work together to determine what a mariner actually sees. A narrower horizontal beam is visible at peak intensity for less time as it sweeps past.

That’s why the light should be evaluated as a complete rotating system, not simply by the rated output of an LED fixture. It should preserve Chatham Light’s identifying characteristic while providing the beam coverage and intensity needed to be conspicuous near shore and offshore.

Until now, remarkably little.

The technology producing the light has changed, but its essential visual and navigational character has remained: a strong rotating sweep visible offshore and across the waters close to Chatham.

As lighting technology improved, that characteristic wasn’t eliminated—it was strengthened. In 1969, a new rotating aerobeacon produced approximately 2.8 million candlepower and was described as visible as far as 28 nautical miles offshore. In 1993, new DCB-224 aerobeacons were installed while continuing the powerful rotating sweep.

The official navigational record reinforces that continuing role. The Light List maintained a 24 NM nominal range for decades and has now been updated to 14 NM, while the U.S. Coast Pilot describes the difficult navigational environment surrounding the light.

In 2026, when the new LED beacon was installed, the Coast Guard described it as providing “the same, if not better, visibility offshore.” That statement concerns expected visibility, while the new Light List entry establishes a 14 NM nominal range. Understanding that distinction should be part of the constructive review.

The opportunity now is to find the best way forward—whether through proven equipment or newer technology—to provide the broad near-shore visibility, powerful offshore performance and recognizable rotating sweep that have long characterized Chatham Light.

Yes. And Chatham has a useful example of how that can work.

When the Mitchell River Bridge needed replacement, its historic significance led to a Section 106 consultation involving federal, state and local interests.

The result combined modern construction with historic character: modern structural technology while preserving important aspects of the bridge’s traditional appearance and the visual experience of its operation as a drawbridge.

Chatham Light presents a similar opportunity. A lighthouse has a nighttime appearance as well as a daytime one. Paint, markings and architecture help define it during the day; the rotating sweep helps define it at night.

Section 106 is, at its heart, a consultation process. We’d like to see the Coast Guard, Town and appropriate state and local historic preservation interests use that process constructively as part of finding the best answer for navigation while preserving Chatham Light’s historic character.

Yes. There are encouraging examples here in the Northeast.

At Montauk Point, the Coast Guard and Montauk Historical Society are working together on a pilot that returned the lighthouse’s historic Fresnel lens to active service using a modern motorized rotation system and LED light source. It’s a particularly interesting example of combining modern technology with the powerful rotating character of a historic lighthouse. See the Montauk Point media links.

At Gay Head Light on Martha’s Vineyard, the Coast Guard and community have worked through changes in lighting technology while addressing the light’s distinctive historic characteristics. Most recently, a modern LED beacon was installed while restoring Gay Head’s historic three-white/one-red characteristic.

At Whaleback Light at the mouth of the Piscataqua River, the Coast Guard worked with lighthouse and maritime stakeholders after concerns were raised about replacing a rotating beacon with a flashing LED. Following an aids-to-navigation study, a rotating beacon was restored.

These situations aren’t identical to Chatham, and no single example dictates the technical answer here. But they show something important: modernization doesn’t have to be one-size-fits-all.

The Coast Guard has worked constructively with communities to combine modern technology with the navigational and historic characteristics that matter at individual lighthouses.

That’s the same collaborative approach we’re asking for at Chatham.

We’re asking the Coast Guard to work with the Town and appropriate state and local historic preservation interests to get Chatham Light’s navigational performance right.

The priorities are straightforward:

1. Near-shore navigation: restore effective coverage and conspicuity across the difficult waters, shoals and harbor approaches described in the U.S. Coast Pilot.
2. Offshore performance: understand the basis for the change from the longstanding 24 NM range to the new 14 NM listing, and agree on the intensity, conspicuity and loom Chatham Light should provide while maintaining its identifying Fl (2) W 10s characteristic.
3. Historic character: preserve, as reasonably possible, the familiar nighttime appearance and rotating sweep that have characterized Chatham Light for generations.

Our preferred solution is a Montauk-style approach: combine a modern LED light source with appropriate rotating optics and reliable drive mechanics to restore Chatham Light’s broad, recognizable sweep. If that is not feasible, the Coast Guard should use an appropriate LED system that restores the key characteristics of the beam—sufficient range, intensity, conspicuity and coverage—while maintaining the light’s identifying Fl (2) W 10s characteristic.

The goal is navigational safety and an effective aid to mariners. Modern technology is one means of getting there, while preserving the historic characteristics of Chatham Light wherever reasonably possible.

That’s what we’re asking the Coast Guard, Town and community to work together to achieve.