The 1960s saw the start of the oil exploration in the North Sea which would dramatically change the economy of the north of Scotland, and would play a big part in the success of the company. However, this decade was mostly spent consolidating the company's experience on maritime civil engineering and supporting the fishing and marine infrastructure in Scotland.
During the 1960s Arch Henderson had two offices, one in Aberdeen which was managed by Ian Henderson, the son of the late founding Partner, Archibald Henderson, and another office in Inverness which was managed by Malcolm Morrison.
One of the major projects of the decade was the deepening of Macduff Harbour along with associated repairs, a new quay and a new fish market. The harbour was closed and drained on 1 March 1965 to allow the works to take place and the harbour was reopened by December that year. The new depth of 10 feet below MLWS allowed for the increasingly larger fishing vessels to berth in the harbour to make use of the new market facilities.
The fishing industry in Shetland also had a welcome boost to its infrastructure with a new pier and a small fish market designed and built in Scalloway. The small island of Whalsay, which is still dominated by the fishing industry, benefitted from a new pier and breakwater in Symbister harbour. The pier also provided a safe berthing space for the inter-isle ferry which had previously had to anchor off shore, with passengers and freight being transferred into small flit boats to reach the ferry, which was not usually a comfortable experience. Arch Henderson also designed a jetty and an oil storage facility in Lerwick which is still used today for the import of heating oil, aviation fuel, petrol and diesel.
A new slipway was designed for the shipbuilding company A Noble & Sons for its facility in Girvan, and a new slipway was created in Peterhead. In Aberdeen the company worked for BP on the Point Law facility.
The Inverness office diversified the range of civil and structural engineering projects, with a variety of small works in the Highlands for private estates, in the form of bridges, sewers, sea walls, and some housing developments. A new ferry berth was also created for Stornoway Harbour.