The Nassau Agreement was signed in December 1962, and the Polaris Sales Agreement was signed in April 1963. Initial construction took place between 1963, when Faslane was chosen as the new Polaris base, and 1968, when the first Polaris boat began its patrol. Safety considerations required that the armament maintenance and the storage facility have its own berth and be at least from the main facility whilst operational considerations dictated that the two facilities should be within an hour's sailing time. Coulport, on the opposite peninsula, met both of these requirements.