More than 1000 ferry trips were cancelled by operator CalMac last year due to technical issues, new figures have shown.
The number is an increase of almost 300 from the previous year, according to a Freedom of Information request by the Scottish Greens.
Green MSP John Finnie, who represents the Highlands and Islands and is the party’s transport spokesman, has called on transport secretary Michael Matheson to launch a review into replacement plans for the fleet.
CalMac said despite the technical faults it boasted a 99.35% success rate, completing 168,000 sailings last year.
According to the statistics, 1069 trips were cancelled last year – compared with 780 the year before – due to technical issues with ships.
In total, 5653 journeys were cancelled, with the majority – 3811 – due to poor weather.
Other reasons included pier work, very low tides and mechanical problems onshore.
The year before, 5383 trips did not run – with 4066 due to adverse conditions.
The numbers come amid a growing controversy over ships due to be built by Port Glasgow shipyard Ferguson Marine for CalMac, which have been delayed and could end up costing more than twice the original price tag.
Mr Finnie said: “Calmac is entrusted to deliver lifeline services to remote and island communities up and down the west coast so it is particularly concerning that the number of cancellations as a result of technical breakdowns has greatly increased in the last year.
“Behind these cancellations are people unable to attend hospital appointments on the mainland, missed job interviews, small businesses unable to send and receive goods, and a loss of important tourism revenue.
“We know that the bulk of the fleet needs renewed. The average age of the Calmac fleet is 23 years and the Scottish Government’s own ferry plan for 2013-2022 highlighted that the majority of the vessels needed to be replaced.
“This hasn’t happened and we’re left with the situation where we have an ageing fleet which requires longer periods of maintenance and repair.”
Calling for a review, Mr Finnie stated local representatives and trade unions must be “at the heart of the procurement process in order to deliver a fleet that communities served by the Clyde and Hebrides services deserve”.
CalMac’s director of operations Robert Morrison said: “Last year we successfully carried out more than 168,000 sailings with 1069 cancellations due to technical reasons, a 99.35% rate of reliability which benchmarks very favourably when compared to other transport operators.
“To increase fleet resilience further we are investing more than £21m during this year’s dry dock maintenance programme, which includes a record £9m investment on vessel upgrades.
“More than 90 major projects will be carried including new engines, replacement pitch control systems, new bow thrusters, replacement ramps and new generators on various vessels.
“We have also introduced a new team to carry out in-service preventative maintenance to help avoid technical issues arising.”
A Scottish Government spokesman said: “Transport Scotland is currently working with CMAL and CalMac to develop investment programmes for major vessels and small vessels with the aim of increased standardisation, taking account of the many and varied routes which CalMac serves.
“The latest Vessel Replacement and Deployment Plan is in final drafting and the intention is to publish this spring.
“While reliability currently stands at around 99.35%, we look forward to working with all interested parties to continue to deliver improvements, building on the substantial investment in routes, services, vessels, harbours and fares which have been made in these services in recent years and which have led to significant improvements in connectivity, capacity, affordability and passenger numbers.”