From a line in a list to light on a hill
Every light is drawn from its own entry in the List of Lights. What the List gives is kept as given; what it does not give, we chose, and each choice is named here.
From the List
390 lights
position, lamp height, listed range, rhythm, the tower's description and remarks: each as the List gives it. 7 more are placed from OpenStreetMap, Wikidata or the directorate's page.
Ours
3 rules
which lights turn, how many beams a lens has, and how strong each is on the ground. The List gives none of these; a chip on each card says so.
Checked against ground
332 lights
have their reach worked out on 72 bearings over real elevation, on a grid of about 300 m.
The rhythm
the List's seconds, never ours
Turning lens
127
flashing lights listed for 15 nautical miles or more: drawn as beams sweeping round. The cut-off is ours.
Blinks in place
219
weaker flashing lights, and every occulting, isophase and quick light: a lantern that brightens and dims.
Steady
32
fixed lights: nothing turns, nothing blinks.
No rhythm listed
19
drawn dim and still; the card says the List gives none.
How many beams a lens is given
2 beams · one turn in 20 s
3 beams · one turn in 30 s
4 beams · one turn in 20 s
Three real lights, seen from above. A single flash is repeated round the lens until one turn takes 20 seconds or more, up to 8 beams; a group of flashes is a group of beams. From any bearing the beams still pass exactly as the List says, so the rhythm is the List's; only the calm of the turning is ours.
Flash lengths
156 listed
For 190 more the List gives the period but not how long each flash lasts; the usual flash for that kind of light is drawn, and the card says so.
Listed, and filled in
Two lights that flash in twos. For the first the List prints every length of light and dark; for the second only the period, so its flashes are drawn at the usual short length with a short gap between them.
Light on the land and the sea
where a beam can fall, and how brightly
Reach, bearing by bearing
On each of 72 bearings a beam is stopped by the least of three things: the listed range (dashed), the curve of the earth for an eye 5 m above the sea, and the ground itself.
Azhikode, listed for 24 nautical miles (44 km): the hills behind it cut the light short on 30 of the 72.
How strong, from how far it is listed
The List gives a range, not candelas. Ours: full strength at 24 nautical miles and over, falling steeply below. A weaker light also reaches less far, and a lamp under 35 m lights less land.
Each point of ground
4 tests
Is it inside a beam now; how far is it from the lamp; can the lamp be seen from it, walking the ray over the elevation with the earth's curve; does the slope face the lamp.
Lights worked at once
22 laptop
- tablet 16
- phone 12
the strongest and nearest the middle of the view. The rest keep their rhythm as points until the view moves to them.
Sectors
44
13 with arcs of colour and 31 with an arc of visibility, read from the List's remarks. Such a light is drawn only inside its arcs, in their colours, to the half degree.
The scene
what is true to life, and what is drawn larger so it can be seen
Heights, drawn taller than life
Hills must read from far off: six times life size at a distance, easing to 1.6 close in. A chip on the map says so.
Towers
Built from the List's words: round, square, six- or eight-sided, framework; colours and bands. On the map far larger than life, in true proportion to one another. On the card and in the row by year, to scale beside a person and a palm.
Two skies
The map opens at Dawn, with the land plain to read and the beams still falling on the hills. Night sits beside it; the choice lasts for the visit.
Which lights show first
183
lighthouses: a tower the List describes that shows 15 nautical miles or more, or a name on the ministry's or the directorate's lists. All 397 lights adds the harbour, breakwater and range lights.
Lesser lights
light no land at all until the view is inside the port, and then weakly. Far out, a turning light shows one soft beam; the others of its lens fade in as the view comes closer.
Still, if you ask
With reduced motion set on the device nothing moves: the lights are drawn at one instant, the voyage is off, and each card's rhythm is a still strip.
What it cannot tell you
Not for navigation
The List's newest correction for these coasts in our copy is notice 34 of 2023. A light built, moved or changed since may be missing or stale.
No beam in the air
The light is shown where it falls, on land and sea. There is no shaft of light at the lantern: every way we drew one read as a grey bar.
No drawn shoreline close in
Close in, land and sea are told apart by tone and relief. A shore of mudflat or salt pan at sea level can read as sea.
Nothing smaller than 300 m
The reach is worked on a grid of about 300 m. It cannot see a building, a sea wall or a narrow point.
Staffed, or heritage
The directorate's pages say neither, so the card shows neither.
Arcs hidden near the light
Where the List says a light is obscured only within some distance, that is not applied.
Sources, dates read and what did not join are on the Data page.