The service expanded with the addition of in 1966, in 1972 and in 1974. The Union Company responded to the competition by converting to take roll-on roll-off (RORO) road traffic and ordering a new RORO ship, . However, the resurgence was short-lived: on 10 April 1968, "Wahine" foundered at the entrance to Wellington Harbour during a storm, resulting in 53 deaths. By the time replacement ship entered service in 1972, competition from the Cook Strait ferries and increased competition from air travel, especially following the National Airways Corporation's introduction of the Boeing 737 in 1968, saw the Wellington-Lyttelton service become uneconomic. The Union Company withdrew in 1974, and after two years under the Ministry of Transport, the service was cancelled in September 1976. In 1982 "Arahura" joined the fleet to replace the ageing "Aramoana" and "Aranui". The faster "Arahura" reduced the time across Cook Strait by 20 minutes to three hours.