THE MARITIME ATLASCape d'Or Data method

DATA METHOD

The Dory Rips of Cape d'Or

How the tide, the arrows, the sea floor and the record on this page were made, what each can and cannot show, and where every fact comes from.

Snapshot: 28 October 2026. Nothing on the page comes from a database. Every moment, place, map layer and source is kept with the page and built from the research made for the reel. Before the page is built, each one is checked: a moment without a source, a place without a basis, or a source the page prints that does not exist stops the build.

The tide clock

The clock runs 30 seconds, evenly, from the predicted low water of 08:44 to the next, at 21:06, on 15 August 2026, Atlantic Daylight Time (UTC−3): 12 hours and 22 minutes. That day was chosen because a satellite passed over the cape on it, 3.6 hours after low water on a big tide.

The water level is the Canadian Hydrographic Service's prediction for station 00240, Cape d'Or: low water 0.73 m at 08:44, high water 11.62 m at 14:46, low water 0.99 m at 21:06, in metres above chart datum, the level of the lowest tides. The service publishes the high and low waters; between them the page draws a half-cosine curve. The real curve in the upper Bay of Fundy is not quite that shape, so the readout between the turns is close, not exact. The station is listed as not operating: these are predictions, not measurements.

The year's figures in section 04 are worked out from the 1,411 predicted high and low waters of 2026 (1,410 rises and falls): the biggest range 11.65 m, the average 8.69 m, the smallest 5.46 m.

The arrows

The arrows are the pilot books' words drawn on the map. They were drawn for the reel and approved by Joel on 15 October 2026, and the page takes them from the reel's map. The words, from the Admiralty's sailing directions of 1885 (p. 190), are repeated in the United States pilot of 1918 (p. 171) and rewritten in Canada's sailing directions of 2021 (ATL 106, paras 117 and 134):

  • with the flood, the stream from Cape Chignecto "sets nearly straight" at Cape d'Or;
  • it makes "a long rip off cape D'Or to the distance of a mile", caused by meeting an eddy that sets toward the cape along its eastern shore;
  • on the ebb, an eddy forms to the westward of the cape.

The same pilot says that inshore the flood "makes a circuit of Advocate bay". It gives no direction, so the map does not draw it. The first draft of the reel's map drew Advocate Bay water running down the cape's west side into the rip; a blind check of the claims found that this misread the text, and the map was corrected before it was approved.

The arrows show where the water goes, not how fast. Their dashes move faster when the stream is stronger, on a sine curve that is zero at high and low water and greatest halfway between. That timing is representative: no source read gives the times the streams turn at Cape d'Or. The pilots give the speed round the cape as 5 to 6 knots (2.6 to 3.1 m/s); no modern measurement at the cape was found.

The front, a dotted line about 1.9 km (1.2 miles) south of the point, is not in the pilot books. It is drawn where the satellite frame of 15 August 2026 shows one, and the page labels it so.

The sea floor

The sea floor is the Canadian Hydrographic Service's NONNA bathymetry: NONNA-100 for Minas Channel (cells of about 107 m) and NONNA-10 near the point (the record says 10 m; the service returned cells of about 13 m). Both are subsets requested from the service's coverage server in October 2026 and kept with the research. Depths are in metres below chart datum; a positive value is ground that dries at low water, shown pale grey-green.

The grids are resampled onto the atlas projection: deeper is darker, on a curve from 0 to 100 m, with a hillshade lit from the north-west with heights stretched six times in the channel and three times at the point, so the scarp, the trough and the sand waves read. Seams one or two cells wide in the survey are filled from their neighbours; land and wider gaps stay empty and show the plain sea colour. The depth lines are every 20 m from NONNA-100 in the channel, and at 10 m and every 20 m from a lightly smoothed NONNA-10 at the point.

The profile in section 03 takes the NONNA-10 cell under each point every 50 m due south of the light: about 17 m at 250 m, 37 m at 500 m, 74 m at 1 km, a trough of 77 to 84 m between 2 and 2.8 km, and 36 to 48 m from 3.5 to 10 km. The research's own profile, taken with a slightly different cell, gave 19 m at 250 m; the reel said "about twenty metres". The steepest slope within 3 km of the light, 32 degrees, and the finding that the floor shows a scarp and a trough rather than a ridge across the channel, come from the research's own measurements of the survey.

The sea floor is not for navigation. The full notice the CHS licence asks for is below and in the page's footer.

The satellite frame

The frame is NASA's Harmonized Landsat and Sentinel-2 product (HLS S30, nadir BRDF-adjusted reflectance), from Sentinel-2 on 15 August 2026 at 15:20 UTC (12:20 ADT), requested through NASA GIBS as a 540 × 960 picture of 3.9 × 7.0 km south of the cape. Its cells are 30 m. The scene is dark, so the page shows it in one tone, its brightness stretched between the 0.5th and 99.3rd percentiles, as the reel did; land is masked by the shore so the atlas's own land fill stays.

The research checked 68 HLS scenes from April to 10 October 2026: 22 were under 15% cloud, and 4 of those fell on the flood 1.8 to 4.2 hours after low water. On 15 August (cloud 2%, a range of 10.9 m) the frame shows a pale foam arc curving east-south-east from the point, a round eddy east of it and a front about 1.9 km south. On 19 September, 26 minutes before low water on a small tide, the same water is smooth. The frame comes up on the clock from 11:50 to 12:50, or stays on with its button.

The shore, the places, the projection

The shore of Minas Channel is Statistics Canada's 2021 cartographic boundary file, asked for the frame alone at 0.0001° and simplified at 0.00005° (about 5 m). The province view uses the Atlas's own outline, as on the other pages. Both are today's shoreline, generalized for a screen; neither is a chart.

The light's position is the Coast Guard's List of Lights 2026, no. 167: 45° 17′ 27.0″ N, 64° 46′ 27.5″ W. Every other place is the province's official name point (NS GeoNAMES), kept with its gazetteer code. All are recorded positions; nothing on the map is placed by estimate except the arrows, which are schematic and say so.

The map uses the projection of every atlas page in the Maritimes: a spherical Lambert conformal conic with standard parallels 44° and 46° N, central meridian 63° W and origin 45° N, so shapes match across pages.

Three kinds of moment

THE RECORD beside the map lists 11 moments of the tide.

  • A predicted time (a solid amber dot; 3 moments): the low and high waters, from the Canadian Hydrographic Service.
  • Seen from space (a half dot; 1 moment): the satellite's pass at 12:20.
  • The pilot books' words (a hollow dot; 7 moments): what the books say happens with the flood or the ebb, placed by the page in that part of the tide and marked "placed". They are not timed by any source. Since the books of 1885, 1918 and 2021 are one text, rewritten, each of these says "one lineage".

The station's history

Section 06 lists 15 moments from 1836 to 2026, each marked by the kind of record behind it. A record of its time is a notice, report, pilot book or list made within a year or two of what it reports: the notices of 1875, the Department of Marine's reports for 1922–23 and 1924–25, the Notices to Mariners of 2017, the List of Lights of 2026. A later history is a compiled account: Lighthousefriends, which quotes the Department's reports, and Lighthouse Digest. A moment that rests on one source says so.

The whistle's start is given as 1874–75: the notices date it from 2 January 1875, and Lighthousefriends, quoting the report, says it ran for some months before, unannounced, because the water supply was not steady. The whistle's pattern (6 s blast, 24 s quiet, twice a minute) is the Nautical Magazine's notice 69 of 1875, read in the cached text. The first light is the Department of Marine and Fisheries' report for 1922–23, which names the Eatonville tower twice. The diaphone is its report for 1924–25, one primary source. The houses' later life rests on Lighthousefriends, with Darcy Snell's own words in a Canada Explore video of 2010 for his part.

Distances and the curve

Distances are great-circle distances on a sphere of 6,371 km between recorded points: the light to Black Rock's name point, 13.5 km (8.4 miles); the light to Parrsboro's, 37.3 km; the light to Eatonville's, 13.8 km. The road distance from Black Rock Road, 307 km, about 3 hours 53 minutes, is Joel's own reading of the fastest route; the page names the road and not a house.

The Earth's curve over 13.5 km is d²/2R = 14.2 m on a sphere of 6,371 km. With the standard allowance for the bending of light in the air near the ground (a refraction coefficient of 0.13), the apparent drop is 0.87 of that, 12.4 m. The page says "about 14 m" and "about 12 m".

Pictures

The 3D pictures are frames of Joel Hirtle's model of the cape, rendered in Blender (Cycles) for the reel: the ground from NRCan's HRDEM lidar, the sea floor from CHS NONNA, the buildings from photographs. They are a model, not photographs, and the captions say so. The fog and the glow of 1922 are the model's weather: no picture of the 1922 tower at the cape cleared for use was found (Library and Archives Canada and the Nova Scotia Archives hold photographs; both need a request).

The photograph of the cape and the picture of Joel filming were made from Black Rock Road; they carry no location data. The title page of 1885 is the Internet Archive's scan of the Google copy, in the public domain. Each picture is kept with a record of its source and licence.

Where the record disagrees

  • Three tides, or one stream and an eddy. Wikipedia and tourism guides (Bradt, 2009 to 2017; The Little Book of Nova Scotia, 2015) say three currents meet off the cape, over a subsurface reef. No pilot book or chart read says three. The page follows the pilots.
  • Apple River or Eatonville. Wikipedia says the 1922 tower came from Apple River; the Department of Marine's report for 1922–23 says Eatonville, twice, and Lighthouse Digest agrees. The page follows the report.
  • 1874 or 1875. The whistle ran from December 1874, unannounced, by Lighthousefriends; the notices date it from 2 January 1875.
  • The light's character. Older secondary lists give a flash every 9 seconds and a fog signal of three blasts a minute; the Coast Guard's list of 2026 gives a long white flash every 6 seconds and no fog signal. The page follows the Coast Guard (Joel, 14 October 2026).
  • The depth at 250 m. 17 m in this page's profile, 19 m in the research's, from neighbouring cells of the same survey.
  • Speeds. 5 to 6 knots round the cape in 1885 and in 2021: the same figures, not two measurements. Measured currents in Minas Passage (up to 5.2 m/s, about 10 knots) are a different place and a different quantity.

What was not read

  • The Department of Marine's reports for 1874–75 to 1877–78, on the whistle's building, cost, the storm and the cisterns. They are on Canadiana, which does not allow scripts; the page uses them through Lighthousefriends.
  • E. H. Rip Irwin, Lighthouses & Lights of Nova Scotia (2003). In copyright; not read.
  • Photographs of the fog alarm station and the first light at Library and Archives Canada and the Nova Scotia Archives. Not reproduced: each needs a request and its terms read.
  • A modern current model or measurement at the cape. None was found open: the CHS tidal current atlas (2015) gives speed bands for the whole bay, and the published tidal models of the area offer no data to download.
  • The origin of the word "Dory". Searches of the old books under several spellings found nothing.

The page follows the rip and the light station. It does not tell the cape's other histories: the Mi'kmaw history of the Fundy shore, and the copper mining at the cape around 1900.

The CHS notice

This page uses the Canadian Hydrographic Service's NONNA data under its licence, which asks a product made from it to carry the following notice in a prominent place:

This product was made by Joel Hirtle and contains intellectual property of the Canadian Hydrographic Service (CHS) of the Department of Fisheries and Oceans. This product does not meet the requirements of the Navigation Safety Regulations, 2020 under the Canada Shipping Act, 2001. Charts and publications issued by or on the authority of CHS must be used to meet the requirements of those regulations. The copyright in the data are and remain the property of His Majesty the King in Right of Canada and shall not be sold, licensed, leased, assigned or given to a third party. The incorporation of CHS data in this product does not constitute an endorsement or an approval of this product by the Canadian Hydrographic Service, the Department of Fisheries and Oceans or His Majesty the King in Right of Canada.

Every source

The list is built from the same source list the page uses, so it cannot drift from the page.

RECORDS OF THEIR TIME

LATER HISTORIES AND COMPILATIONS

THE MAP AND ITS DATA

JOEL HIRTLE'S OWN WORK

  • Joel Hirtle's Google Maps route from Black Rock Road to Cape d'Or (fastest route, about 3 h 53 min), 21 October 2026307 km by road. Joel's own reading of the route; the start is given as the road only.
  • Joel Hirtle, photograph and video of Cape d'Or from Black Rock Road, Kings CountyJoel's own work.
  • Joel Hirtle, 3D model of Cape d'Or (Blender, Cycles), made for the reel of October 2026Ground from NRCan HRDEM lidar, sea floor from CHS NONNA, buildings from photographs. A model, not a photograph. Joel's own work.