MV Iona (VII) was the first of a new generation of major car ferries built for the Scottish Transport Group to replace the ageing 1939 mailboat Lochiel, serving Islay, Jura, Gigha and Colonsay from West Loch Tarbert.

She was troubled by a run of early breakdowns: starboard ramp, hoist, forward capstan, bow-thrust unit and automatic steering.

[1] The absence of a turntable at the forward end of her car deck made the management of on-board traffic difficult.

In April 1972 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 Loch Seaforth 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.

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.

The arrival of the new MV Claymore 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.

After Western Ferries finally abandoned their Islay service at the end of September 1981, Cal-Mac offered more calls to Port Askaig.

Each winter Iona returned to Oban, relieving Claymore and usually had her own refit in February or March, sometimes at Govan, but more usually in Greenock.

Losing her crane in 1983 and a Perspex canopy on her limited open deck space, she was extensively refurbished in 1984.

[1] In May 1989, Iona was once again displaced by Claymore, cascading to the Islay station on the commissioning of MV Lord of the Isles.

For the first time in sixteen years, she was again on a purely hoist-loading route, until she opened linkspans at Mallaig and Armadale on 1 April 1994.

She was a great success at Armadale seeing an increase in traffic, and offering a varying routine of weekend sailings from Mallaig to Castlebay, Lochboisdale.

[citation needed] From 2006 to 2009 Pentalina-B was chartered out in her off-season, to carry livestock across the English Channel from Dover.

She was chartered to Cal-Mac in December 2008, operating the Ullapool - Stornoway freight run in place of MV Muirneag.