Isle of Cumbrae was launched shortly before Christmas 1976 and entered regular service the following April. Her design was basically a scaled-down version of the Skye ferries Kyleakin and Lochalsh. Like them she was propelled by Voith Schneider units fore and aft, in diagonally opposite corners of her hull. She had three lane on her car deck, each capable of holding six cars, giving her a total capacity of 18. Her passenger accommodation was located down the length of the hull on her starboard side, above which sat her small wheelhouse. The loading method for both cars and passengers was via a ramp at either end of the car deck. Each ramp was folded in two sections, like those on the Island Class ferries. The main body of the ramp would be lowered whilst approaching the slipway and the forward section would be lowered once the vessel was actually in position on the concrete slipway.

Arriving at Largs early in her career

After entering service in early April 1977 the Isle of Cumbrae quickly solved all the problems encountered previously with the smaller ferries. The crossing was only of ten minutes duration and with five minutes at each terminal she could complete two return sailings each hour.

She remained on the crossing from Largs until summer 1986. Initially at this time (from 4^th July) she was paired with the new Loch Striven which could carry twelve cars and was of a similar design, but after exactly a month the Isle of Cumbrae was transferred to the Western Isles, effectively switching places with the new Loch Linnhe (the second of four identical sisters built for the company). Whilst the new twins took control of the Largs route the displaced Isle of Cumbrae took over the Fishnish – Lochaline crossing in the Sound of Mull. The previous long-term vessel here had been the Canna which of course could only carry six cars, so the arrival of the Isle of Cumbrae was a great improvement for the route as it meant that for the first time, commercial vehicles could be carried.
 

The new crossing was only 15 minutes in length and quickly proved popular, although on the return leg of the journey from Mull to Lochaline, a number of passengers would be confused by the vessel swinging round and proceeding in what appeared to be reverse. The reason for this being the angle at which Lochaline slipway was set facing up the loch. It was simply easier for the ferry to turn at Fishnish than in the confines of Lochaline itself. Sailing from early morning to late evening in the high summer, Isle of Cumbrae could fit in a return sailing every 40 minutes, offering up to nearly 20 crossings each day.
Her introduction on this back-door route was a huge success. Drivers could turn up for any given sailing and be virtually guaranteed of a space on the ferry – unlike previously when many would see the Canna arrive and depart two or more times before finally being able to board. This new development meant that day trips to Mull from places such as Fort William and beyond were now possible, as were day trips to Inverness for the islanders, provided they were prepared for a full day out.

Arriving at Fishnish, Mull

The former Cumbrae ferry lasted on the Lochaline crossing for a further decade before she began to leave vehicles behind. Previously, at busy periods such as the Mull Rally weekend, she would be assisted by the Coll or one of the other Island Class ships, however by 1997 it was clear that she needed replacing with an altogether larger ferry.
 

Covering on the Kyles of Bute crossing

Her replacement duly arrived on the scene in July 1997 in the shape of the Loch Alainn, capable of taking 24 cars on her wide car deck. The Isle of Cumbrae was soon found alternative employment however, and in a matter of days she was to be found in the Kyles of Bute having replaced Loch Riddon on the short crossing from Colintraive to Rhubodach on Bute. Here too she brought an increase in the number of cars that could be accommodated on each crossing – her predecessor taking a maximum of 12 on the three minutes sailing. She did of course end up venturing back to her original route from time to time on relief duties or at peak periods (either Loch Linnhe or Loch Riddon would switch places with her).

Her period on the Kyles of Bute was relatively short though. She remained there for the 1998 season whilst a new pier was constructed at Colintraive and was subsequently replaced by the much larger Loch Dunvegan in early 1999. Following this latest displacement, the Isle of Cumbrae was transferred to the now year-round Tarbert – Portavadie route across Loch Fyne, although she was only on this for the duration of the summer timetable. Winter would see her take up a relief role, covering on the Colintraive and Lochaline crossings for the larger Loch Dunvegan and Loch Fyne respectively.

On her current summer role pictured in Loch Fyne