This curious looking object a few miles to the South East of Bembridge started life during the First World War as part of an anti-submarine defence system. During 1916 the British Admiralty, alarmed by the losses of allied merchant shipping to German U-boats designed four or six towers that were to be built and positioned in the Straits of Dover. They would be linked together with steel nets and armed with two 4" guns. However when the Armistice was signed in 1918 only one of the planned towers was anywhere near completion. The others were dismantled but what was to be done with this 92 foot tall metal cylinder (costing one million pounds sterling, in those days), sitting on its raft of concrete?

Until the end of the first World War the dangerous Nab Rock had been marked by a lightship, and it was decided to replace this with a fixed lighthouse. The new lighthouse was floated into position and the concrete raft (189ft long, by 150ft wide, by 80ft deep) flooded so the tower could sit on a shingle bank near the Nab Rock.
As can be seen from the photograph the tower took up a distinct angle (3 degrees from the vertical towards the Northeast) when it settled. The lighthouse used to be manned by a crew of four, but in common with all Britain's lighthouses it is now unmanned and is fully automated.

During WWII the Nab was armed with two 40mm Bofors Guns and was credited with shooting down 3½ enemy aircraft (the half was shared with a passing ship).

The tower still provides a welcoming sight to seafarers returning to the Solent at the end of their voyage. In November 1999 the Nab was hit by a freighter, the Dole-America, carrying a cargo of bananas and pineapples. The ship was badly damaged and only avoided sinking by being run-aground. The base of the tower suffered only superficial damage.

English & Welsh lighthouses are run and maintained by Trinity House.