Eric Mowbray Merrifield was born on 20th March, 1914 in Eldorado, Southern Rhodesia. 

Eric Mowbray Merrifield was the System Harbour Engineer of the Port of East London from 1st September, 1961 until his retirement in 1976. He is notable for the invention and development of the Dolos, an armour block used in breakwaters, groynes and harbour walls to dissipate the immense energy of waves, maintaining the integrity of the structures.

Aubrey Kruger (21 July 1935 – 19 July 2016) was a South African draughtsman and inventor. He worked as a draughtsman for the South African Railways and Harbours Administration in East London, Eastern Cape, until 1966. 

Kruger invented a “Dolos”, a concrete block, in 1963 after being instructed by the South African Railways and Harbours Administration to find a solution for the sea eroding the harbour. 

A dolos is a reinforced concrete block in a complex geometric shape weighing up to 80 tonnes (88 short tons), used in great numbers as a form of coastal management to build revetments for protection against the erosive force of waves from a body of water. 


The design of the dolos is usually credited to the South African Eric Mowbray Merrifield. In the late 1990s the claim of Aubrey Kruger gained more prominence. Kruger's claim is that he and Merrifield had considered the shape of concrete blocks to be used to protect East London's extensive breakwaters for the City's non-natural harbour, following a major storm in 1963.

Merrifield wished to design a block that did not break up or shift when struck by the sea; that was cheap; and that did not require precise placement. Kruger stated that he went home for lunch, cut three sections from a broomstick, and fastened them with nails into an H-shape with one leg turned through 90 degrees to create the distinctive dolos shape. Merrifield was intrigued by the object and had Kruger draw a plan. 

They are used to protect harbour walls, breakwaters and shore earthworks. In Dania Beach, Florida, dolosse are used as an artificial reef known as the Dania Beach Erojacks. They are also used to trap sea-sand to prevent erosion. An order of 10,000 dolosse are required for a kilometre of coastline. It is used all over the world in harbours.

According to en.wikipedia