Bincleaves groyne and the north-eastern breakwater

Bincleaves groyne and the north-eastern breakwater are two breakwaters enclosing Portland Harbour, constructed between 1893 and 1906. Later 20th-century alterations and additions have been made. All buildings, structures and plant added after 1945 are excluded from this listing.

The breakwaters are built of large blocks of Portland stone, with granite facings to the circular pierheads. They are approximately 1.3km long and separated by the north ship channel. Each breakwater has three circular pierheads, each with a diameter of about 30m.

The seaward side of each breakwater is battered and constructed of large, bolstered stone blocks. The inner, elevated road is faced with coursed blocks of Portland stone, and the lower road is bordered by piles of large Portland stone blocks. Each pierhead has a stone staircase on its inner face, along with bollards and winches associated with the boom. A landing stage is located halfway along the length of each breakwater.

The north-eastern breakwater features a lighthouse, a 22m cast-iron structure made up of a skeletal, hexagonal frame around a central cylinder with a domed lantern by Chance Brothers & Co. There is also a concrete circular gun platform and holdfast for a rare First World War 3-inch 20cwt anti-aircraft gun, along with four ammunition lockers.

Bincleaves groyne includes an early 20th-century coastal battery and long and short range torpedo firing ranges. A building associated with the short range torpedo pier has been clad in corrugated iron and is substantially altered.

Both breakwaters retain First and Second World War observation posts and searchlights constructed of concrete and brick, alongside 29mm spigot mortar gun emplacements.

According to section 1(5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990, any buildings, structures and plant added to Bincleaves groyne and the north-eastern breakwater after 1945 do not possess special architectural or historic interest.