His specialist experience was structural engineering which led to an interest in hydro-electric projects, dams, shipyards, docks and industrial developments.
[2] One of Geddes' most notable projects, under the overall direction of James Arthur Banks and later constructed by the contractor Marples Ridgway,[3] was his contribution to the design of the Allt na Lairige dam in Argyllshire in the 1950s.
This was the first concrete dam in western Europe, and possibly the world, to be prestressed by using high tensile steel bars, bolted either end, to compress the structure.
One of his outstanding achievements was the major shipbuilding dock at the head of the Musgrave Channel in Belfast for Harland and Wolff.
His proposers were Hugh Sutherland, William Thomas Marshall, Ian Sneddon, Anthony Cusens, Robert Simpson Silver and Arnold Hendry.