Capacity on ferry crossings from Ullapool to Stornoway has come under scrutiny after it was announced vehicle travel is already fully booked for the rest of the week – with the main tourism boom still to come.
Transport Scotland said the increased volume reflects the success of the introduction of the road equivalent tariff (RET) scheme which has boosted island tourism.
A spokesman added that a study was looking at ways at how further improvements can be made to the service.
Local councillor Ian Cockburn said the capacity problems can cause inconvenience and he advocated the possibility of an additional ferry in the future.
Harbour improvements have been earmarked in the long term to extend berth space for additional vessels.
However, one islander spoke of trying to travel by car to Ullapool by ferry for the last two weeks, but has been unable to due to the ferry being fully booked.
The passenger, who wished not to be named, said: “I have been trying to get over to Lewis for the last couple of weeks but have been unable to – something has got to change.
“I tried to book on Tuesday to get over to see my grandfather and grandmother on Lewis but it has been just awful.
“I was the first reserve the other week and even still couldn’t get.
“I can’t even go over as a foot passenger as my grandparents are in their 90s – I can’t ask them to come and pick me up and to be honest I need a vehicle over there.”
A Transport Scotland spokesman said: “Over £1.4 billion has been invested in ferry services across the Clyde and Hebrides since 2007, including the MV Loch Seaforth and harbour upgrades at Stornoway and Ullapool.
“We are continuing to invest in new vessels and ferry infrastructure to renew the fleet.”
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He added: “Increased vehicle carryings reflect the success of RET fares and the welcome growth of island tourism, but also mean that there are increasing occasions where popular sailings are fully booked for people wanting to travel with a vehicle.
“Following the completion of the current appraisal study, we will be engaging with Outer Hebrides’ stakeholders on next steps.”
A CalMac spokesman: “I’ve checked the statistics with last year and can confirm that there is continuing growth in traffic on this route.
“I would encourage people to book as far in advance as they can to ensure they can get on the sailings they would prefer.”
He insisted there was still some passenger space available on every sailing so far this week, but it was full for the rest of the week for vehicles.