Daymarks and Lighthouse Colours
The Problem of Daylight Navigation
A lighthouse is most obviously useful at night, when its light cuts through the darkness and allows a navigator to fix position with precision. But ships move in daylight too, and the tower itself — when it can be seen against a coastline — carries navigational information that is entirely independent of any lamp. The challenge is making that tower unambiguous: a plain white cylinder seen against a white chalk cliff, or a grey granite tower against grey granite headland, tells a navigator very little. This is why lighthouse authorities around the world have painted, banded, and patterned their towers in schemes calculated to make each one distinctive from every nearby structure that a mariner might see from offshore.
The daymark is any visual feature — colour, pattern, shape, or combination of these — applied to a lighthouse or other aid to navigation specifically to make it identifiable by day. The term is used broadly in American practice to describe a dedicated non-illuminated structure serving this purpose, but in the context of lighthouse design it refers to the tower's visible characteristics. These characteristics are recorded in official publications alongside the light's nocturnal character, giving the navigator a single reference that covers both day and night identification.
Stripes and Spirals
Vertical black and white stripes are among the most recognisable patterns applied to lighthouse towers. Cape Hatteras, the tallest brick lighthouse in the United States at 64 metres, carries a bold spiral stripe pattern in black and white that was applied in 1873 specifically to distinguish it from the nearby Bodie Island lighthouse, which has horizontal bands. The pattern is visible in clear weather from a distance sufficient to serve as a useful positional fix, and it has become so associated with the tower that it appears in the official seal of the Cape Hatteras National Seashore.
Spiralling stripes appear at several other American lighthouses, notably Cape Lookout in North Carolina, where the black-and-white diamond pattern creates an optical effect visible at considerable range. The diagonal and spiral patterns were preferred over simple horizontal banding in some situations because they remain distinctive as the tower's apparent orientation changes with the viewer's position. A horizontal band read from dead ahead may look very different from one seen at an oblique angle; a spiral maintains its character over a wider range of bearing.
In British waters, Trinity House has standardised patterns for its towers over many years. The lighthouse at Cape Wrath is painted white, making it visible against the dark headland. St Mary's lighthouse at Whitley Bay wears white paint on its tower with a black band at the gallery. Several Irish lights operated by Irish Lights show red bands or painted sections that serve as geographic identifiers in addition to the light's nocturnal character.
Colour as Identification
A single colour, applied to the whole tower, can be as distinctive as a pattern if the background against which the tower is seen differs markedly from the colour chosen. The red-painted lighthouse at Galeota Point in Trinidad stands against dense tropical vegetation; the white tower at Portland Bill in Dorset stands against the pale limestone of the Bill itself. The choice is driven by contrast with the background, not by any intrinsic meaning attached to the colour.
However, colour on lighthouse towers has sometimes been standardised within a national system to carry positional meaning. In Sweden, the Lighthouse Authority painted towers on the southern coast differently from those on the north-eastern coast, so that a navigator uncertain of his position could at least identify which stretch of coast he was on from the tower's colour scheme. Similar regional coding existed in parts of the Baltic.
Sector lights use colour to convey directional information to mariners: a light showing white in the safe channel, red on the shoal side, and green on the deep-water side, guides a vessel through a narrow passage without the navigator needing to take a bearing. The coloured arcs of a sector light are produced by coloured glass panels in the lantern, not by the tower's painted exterior — but some towers are painted to correspond with their coloured sectors as an additional day identification.
Material and Natural Colour
The original colour of many lighthouses was determined simply by the material from which they were built. Granite towers like Bell Rock and Bishop Rock were left as bare stone, their grey or pinkish colour sufficient to distinguish them from surrounding water in good visibility. Brick towers were often rendered and whitewashed, both to protect the brickwork from salt penetration and to increase the tower's visibility. In tropical climates, limewash was reapplied annually because the intense sun bleached it rapidly; in northern climates, the period between painting was longer but the physical difficulty of the work — painting in high winds and low temperatures — was greater.
Cast-iron towers presented different choices. The Bolivar Point lighthouse in Texas, a cast-iron structure of the 1870s, was originally painted black. Many cast-iron screwpile lights in Chesapeake Bay were painted in combinations of white, red, and black to distinguish them from one another in a waterway where multiple similar towers were visible simultaneously from a vessel in the channel.
The colour of the lantern room and its surrounding gallery is usually painted black, creating a consistent cap on towers of varying colour below. The black lantern room serves a practical purpose — it absorbs heat and reduces glare that might otherwise interfere with the keeper's view from the gallery — but it also provides a consistent visual cue at the top of the tower that helps identify it as a lighthouse rather than another structure.
The Day Beacon
Where a lighthouse stands in a position where its nocturnal light is of limited value — because traffic is predominantly in daylight, or because the position is well within a harbour — a day beacon may serve the navigational purpose without any lamp at all. Day beacons are essentially skeletal or solid structures carrying a distinctive topmark and painted in standard colours. They are common in American Intracoastal Waterway practice, where thousands of short structures mark the channel with standard red and green colours corresponding to the directions 'leave to port' and 'leave to starboard' when proceeding from south to north.
In the approaches to major ports, the combination of day beacons, range lights, and full lighthouse towers creates a system in which every structure carries both a diurnal identity (shape, colour, pattern) and a nocturnal one (light character). A navigator using modern electronic charts can verify visual observations against a database that records both sets of characteristics for every aid in the system. The daymark does not become redundant in the electronic age — it provides a visible, unambiguous, non-electronic confirmation that the position on screen corresponds to the position in the real world.
Maintenance of Daymarks
Keeping lighthouse colours vivid requires sustained effort. Salt air degrades paint rapidly; the ultraviolet radiation at exposed coastal sites accelerates fading; biological growth — algae, lichen — obscures patterns and changes apparent colour from offshore. Trinity House schedules repainting cycles for its towers based on exposure assessment, with the most exposed stations repainted on four-year intervals and sheltered harbour lights on longer cycles.
The painting of an offshore lighthouse, particularly one accessible only by helicopter or small boat in favourable conditions, is a logistics exercise in miniature. The paint itself must be formulated for salt resistance and UV stability. Application at height requires rigging or working platforms. For stripped masonry towers like the Fastnet Rock off southwest Ireland — which was being recoated in 2022 when a fresh Fresnel lens was also installed — the scaffolding required to paint the full tower represents a significant proportion of the total project cost.
Some towers have become so strongly identified with their colour and pattern that proposals to change them generate public opposition. The candy-cane striping of the Cape Hatteras tower, the all-black paint of the Westhoofd lighthouse in the Netherlands, the red top of the Heceta Head lighthouse in Oregon — these have become part of the identity of the lighthouse in the popular imagination, as much as the light character or the building's history. They are navigational instruments that have also become landmarks in the cultural sense.
Exploring the daymark variety of the world's lighthouses is one of the pleasures of the interactive Open the map, where you can see the marked characteristics of towers across every coast and inland waterway.
Standardisation and Its Limits
The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) has worked to standardise maritime buoyage and, to a lesser degree, lighthouse marking across member states. The cardinal and lateral buoy systems are now largely unified across most of the world into two systems (IALA A and IALA B), but lighthouse tower colours remain largely national in character. There is no international standard governing whether a particular lighthouse should be white, red, black, or striped, beyond the general principle that the daymark should distinguish the tower from its background and from adjacent aids to navigation.
This means that the variety of lighthouse colour and pattern in the world reflects the accumulated decisions of dozens of national lighthouse authorities over several centuries, each applying its own standards and aesthetic judgements. The result is a visual richness that mirrors the diversity of the coasts themselves.