Caledonian MacBrayne this week tightened up procedures by weighing vehicles classed as "light goods vans" before they boarded. Those exceeding the 3.5-tonne limit were turned away with the threat of police action.
Hauliers said that breaches of the limit had previously gone unchecked and unpunished and it had been common practice, enabling them to carry more essential merchandise to the islands. The warned enforcement of the rules means the cost to hauliers could rise as much as four times, meaning islanders will face a price hike in their deliveries.
But CalMac senior manager Ian Fox said overweight vehicles were unsafe to drive, and overloading a van could result in injury or damage on board a vessel.
A CalMac spokesman added: "We have anecdotal evidence that some vehicles may be overloaded and feel we have no option but to take this step. We are certain that customers will understand the importance to everyone's safety of ensuring our crews know precisely the weight of vehicles being carried."