Media playback is unsupported on your device Media caption The ramps will have to be modified before it can be used

A new £6m replacement Strangford ferry remains tied up in County Down because problems with the ramps mean vehicles are unable to drive off it.

The ramps on the vessel, which was specifically built for the Strangford Lough crossing, will have to be modified before it can be used.

As it stands, cars would be unable to disembark from the vessel at high tide.

The Stormont Executive paid £5.7m for the bespoke ferry.

It is intended for use on the half-mile crossing between Portaferry and Strangford.

During recent sea trials in Strangford Lough, it emerged that the ramps on the ferry do not drop low enough to allow cars to drive off them when the ferry docks at high tide, as the ramps stop before they reach the slipway.

Image caption The ramps on the ferry do not drop low enough for cars to disembark

The ship is currently moored in Strangford awaiting modification.

Strangford resident Sheila Cunningham expressed anger at the news: "It appears to be a simple mistake that should not have happened," she said.

"Most children would know that one bit ought to fit the other bit. It arrived with great pomp and circumstance and we all welcomed it, but now it's sitting there unused."

The new vessel, called the MV Strangford II, was originally scheduled to begin operating last summer, but will remain tied up until the repair work is carried out.

A spokesperson for the shipyard which built the vessel, Cammell Laird in Liverpool, said it delivered the ferry to the specifications asked for.

Image caption A DOI spokesperson declined to say how much it would cost to fix the problem and who would pay for the work

"Whatever the technical difficulties are, it is not the responsibility of Cammell-Laird," it said in a statement.

"All handover requests were made. We delivered what we were asked to deliver. The ramp meets the specifications we were given."

Strangford Community Association chairman Gary Laverty said the news was a blow to local residents: "Basically, we're down to one ferry at the moment. If that one breaks down, that's it, I don't know what we'll do," he said.

Image caption One local resident, expressing anger at the news, suggested a child could have worked out the issue

"They spent £750k redesigning the new ramp over the summer. So why doesn't it work? What's going on?"

Infrastructure Minister Chris Hazzard, whose constituency includes Strangford village, was unavailable for interview.

Image caption Community representative Gary Laverty said the news was a blow to local residents

Asked who was responsible for the mistake, the Department for Infrastructure (DFI) said in a statement: "The department's specification required the ferry to be designed to handle the tidal requirements at Strangford."

A departmental spokesperson declined to say how much it would cost to fix the problem and who'll be paying for the work. In response to questions about the cost, the spokesperson said: "At present the priority for the department is to get the new ferry into service.

"While the department regrets the delay to the new service, health and safety issues must always take priority."

The other ferry on the route, the Portaferry II, will continue to provide regular ferry crossings until the new ferry begins service.

The spokesperson added: "The MV Strangford II will enter service as soon as a passenger certificate has been issued by the Maritime and Coastguard Agency. At present we do not have a date for this but expect this to be early in the new year. "