Iona moved to the Western Isles, serving Port Askaig and Colonsay, but from Oban rather than West Loch Tarbert. From 1 May she displaced the ageing as the Stornoway mailboat, and offered a car-carrying service to Kyle of Lochalsh and Mallaig. Iona's basic passenger facilities were less than ideal for the very long sailing to the West Highland railheads. Ullapool had been selected as a more suitable mainland port and Iona inaugurated a new terminal and linkspan there on 26 March 1973. Hoist loading continued at Stornoway for another two months. Thereafter Iona bow-loaded at Stornoway and stern-loaded at Ullapool. She was not a popular Lewis mailboat. Major service problems began on 13 June 1973, when the Stornoway linkspan broke down. Iona had to hoist-load, again, for three days. Then Iona herself broke down, and for several days sailed at 10 knots on one engine. The newly rebuilt also lay idle at Stornoway. Iona again suffered engine trouble in July and spent the rest of that season as the Oban - Craignure ferry, opening the new Oban linkspan on 15 October. On 29 April 1974, still without a permanent role, she started a new fast "Marine Motorway" from Oban to Castlebay and Lochboisdale, inaugurating a Lochboisdale linkspan that July and berthing there overnight. Iona included Coll and Tiree only in her winter roster, which also included a non-landing call at Tobermory. She still used her lift at Barra, Coll and Tiree. Even without Coll and Tiree, the sail from Oban to Barra and South Uist was still a long one and, with very early morning departures. Iona's lack of sleeping berths was greatly criticised. In her 1975 refit, a new deckhouse was added, aft of the officers' accommodation and incorporating eight double cabins. MV Iona completed five seasons on the Oban - Castlebay / Lochboisdale service, but proved increasingly too small, especially with the heavy year-round army traffic to Uist bases via Lochboisdale. The arrival of the new at Oban and the purchase of Western Ferries' Kennacraig facilities in October, finally allowed Iona to take up the Islay service on 15 February 1979. At first she gave three return runs daily between Kennacraig and Port Ellen, with two on Sundays. From 24 October 1979, she gave two calls weekly at the newly extended Port Askaig pier. After Western Ferries finally abandoned their Islay service at the end of September 1981,