The Volunteers Who Have Measured One Harbour’s Tide Since 1890

The Westmere Harbour Board installed the gauge in 1890 for the pilots who brought colliers and timber ships over the bar, and for 41 years it paid a tide clerk to look after it. In 1931, short of money, the board abolished the post. The gauge would have stopped there, except that the Westmere Seamen’s Mission, a reading room and boardinghouse for sailors at the top of Fish Street, offered to keep it going with volunteers. The mission closed in 1988; the rota simply carried on without it. There are 11 people on it now, most of them retired from the sea, and between them they cover the week. By their own count, the hand readings have missed 19 days in 136 years, most of them during a single week of snow in 1947.

The gauge itself has barely changed. Beneath the shed is a stilling well, a cast-iron pipe as wide as a dinner plate, sunk into the harbor floor and open to the sea only through a small hole near the bottom. Inside the pipe a copper float rides up and down with the tide, and a wire from the float runs up over the brass wheel to the pen.2 A clock in the drum turns it once a week. Every Monday, whoever is on duty unclips the old chart, rolls it, pencils the dates on the outside, and clips on a new one. There are about 7,000 of these rolls, and nearly all of them survive.

Since 2009 Westmere has also had an electronic gauge, a radar unit on a gantry at the end of the quay that bounces a signal off the water every second and sends a one-minute average to the National Coastal Survey in Corran. The Survey asked the rota to keep reading the staff anyway, as a check on the radar, and to keep changing the charts. In the winter of 2014 the arrangement paid for itself. Storms knocked out the radar’s power for 11 weeks, and the only record of the harbor’s tides through the worst surges in a generation is a purple line drawn by a mechanism installed when the pilots still worked under sail.

Write what you see

Pinned to the inside of the shed door, behind a sheet of yellowed plastic, is a card of instructions typed in 1931 for the first volunteers. Most of it concerns the clock and the ink. The last three lines are the ones every new member of the rota is told to learn by heart: Read the staff at the top of the tide, not after. Write what you see, not what you expect. If in doubt, write that you are in doubt.

Hazel Imrie, 74, was first mate on the island ferries for 22 years and talks about those lines the way other people talk about scripture. “The last two are the whole of science,” she says. “People want to tidy things. You read 4.63 and you think, well, the tide table said 4.58, I must have misjudged the swell, and you write 4.60. You don’t. You write 4.63, and if you weren’t sure, you write ‘not sure.’ Then whoever comes after you can decide.” The logbooks are full of doubts: swell confused, glasses misted, staff fouled with weed, reading poor. As far as anyone has found, not one figure in 136 years has been erased. Mistakes are struck through with a single line, initialed, and corrected alongside.

There are 47 volumes. The first 11, covering 1890 to 1931 and written in the tide clerks’ copperplate, are kept in the Westmere Municipal Archive. The other 36 live in a steel cabinet in the shed, under a shelf with a kettle on it.3

What the line says

For most of the 20th century, nobody did much with any of this beyond printing tide tables. Then, in 2017, the National Coastal Survey went looking for long records. Satellites have measured the height of the open ocean with great precision since the early 1990s, and computer models can estimate how sea level ought to respond to a warming climate, but both need checking against what has actually happened on real coastlines, over spans long enough to see a trend through the noise of storms and seasons. Records that reach back into the 19th century without long gaps are rare. Oskar Feld, a sea-level scientist at the Survey, found Westmere’s mentioned in a 1960s harbor report and drove down to see it. “I expected a shoebox,” he says. “I got a shed full of paper and a man who could tell me the high water for any date I named.”

Over two years, the Survey scanned the charts, digitized the pen trace hour by hour, and checked it against the logbooks. The result is a sea-level record for Westmere from 1890 to the present with fewer than three hours in every hundred missing.^* It shows mean sea level at the harbor about 27 centimeters higher than it was in the 1890s. More telling than the total is its shape. From the 1890s to the 1980s, the sea at Westmere rose by a steady 1.6 millimeters or so a year. Since 1990 it has risen at more than twice that rate.

Part of that rise is the ocean, warming and expanding and taking on meltwater from land ice, much as the global models describe. But part of it is Westmere itself. The quay and most of the lower town stand on land reclaimed from the estuary in the 18th century, and repeated surveys tying the tide staff to a benchmark cut into bedrock beneath the steps of the old customs house show the quay sinking by about 0.4 millimeters a year as the fill slowly compacts.^† No regional model would have known that. Nor would it have known that the quay floods at a lower water level than the tide tables assume, because a 1970s repair left a dip in the stonework at the bottom of Fish Street. Those things are in the logbooks, in someone’s handwriting.

Feld is careful about what the record does and does not prove. One harbor is not the planet; the global rise rests on hundreds of gauges and three decades of satellites, not on Westmere. What the rota offers is something a model cannot: what has actually happened, here, at the bottom of this street. In the 1950s the logbooks note water over the quay edge at Fish Street once or twice a decade. In the 2010s it happened about nine times a year. In 2025 it happened 23 times. “The models tell you what the sea is likely to do on average,” Feld says. “Bernard’s numbers tell you what it did to his street.”

The handover

Lusk’s eyes are going. He has cataracts in both, the left worse, and on gray mornings the centimeter marks on the staff blur into one another. In January he told Imrie he would give up his Tuesday slot at Easter. His replacement is Ines Carrow, 27, who crews the pilot launch out of Westmere and joined the rota in 2023 after walking past the shed every day for two years and finally knocking on the door. She is younger than the next-youngest member by 31 years.

A handover at the Tide House is not a ceremony; it is a series of Tuesdays. Since January, Carrow has met Lusk on the quay at every Tuesday daylight high water, and he has shown her the things the card does not say: how to stand so the low sun does not glare off the enamel; how to time the swell by counting, so that you read the middle and not the hope; how to coax the drum clock when it runs slow in a cold snap, with a hair dryer kept in the cabinet for the purpose. “He makes me read first and then tells me his number,” Carrow says. “We’ve been within a centimeter every time since February. He says that means I’m ready. I think it means he’s being kind.”

On the Tuesday after Easter, Carrow read the tide alone for the first time. Lusk came anyway, and stood at the top of the slipway with his hands in his pockets, very obviously not watching. She crouched at the staff, counted the swell under her breath, stood up, and went into the shed to write her number in the logbook, below a column of figures in handwriting that changes every few pages—a clerk’s copperplate, then the round hands of a dozen retired sailors, then Lusk’s squared-off capitals. She did not tell him the number, and he did not ask. He can read it in the book, like everyone who comes after him. That is what the book is for.