Portland Harbour

Portland Harbour is beside the Isle of Portland, Dorset, on the south coast of England. Construction of the harbour began in 1849; when completed in 1872, its 520-hectare (1,300-acre) surface area made it the largest human-made harbour in the world, and it remains one of the largest in the world today. It is naturally sheltered by Portland to the south, Chesil Beach to the west and mainland Dorset to the north. It consists of four breakwaters: two southern and two northern. These have a total length of 4.57 km (2.84 mi) and enclose approximately 1,000 ha (2,500 acres) of water.

Portland Harbour was built by the Admiralty as a facility for the Royal Navy (though access was also available to merchant ships); on 11 December 1923 it was formally designated HM Naval Base (HMNB) Portland, and continued to serve as such until closure in 1995.

History

Creation of harbour of refuge (1844–1872)

The original harbour was naturally sheltered by the south coast of England, Chesil Beach and the Isle of Portland, providing refuge for ships against weather in all directions except east. The harbour had already been used by ships for centuries when, in the 16th century, King Henry VIII built Portland Castle and Sandsfoot Castle to defend the anchorage. Prompted by the expansion of the French naval port of Cherbourg, just across the English Channel, the Royal Navy established a base at Portland in 1845; a scheme for the harbour to be transformed into a refuge had been granted parliamentary approval the year before. Portland was the first naval anchorage specifically designed for the new steam navy.