HMS Unicorn goes under the microscope for preservation project

The survey team are examining every piece of timber on the ship's exterior

Perched on a pontoon above the chilly water of Dundee's Victoria Dock, surveyors are inspecting every section of one of the world's oldest ships.

HMS Unicorn has been a feature of the city since 1873, half a century after she was built at Chatham Dockyard in Kent.

The former training ship has weathered many storms, including almost being scrapped in the 1960s.

But 200 years of exposure to the elements, including the wind and rain lashing the survey team today, has left its mark.

HMS Unicorn has been based in Dundee since 1873

"Generally, on the starboard side, which is what we're surveying at the moment, it's not great," says shipwright Dominic Mills, from surveyors T Nielsen & Co.

"Most of the planking is in a very poor state."

The survey is part of a major conservation project that will see the ship moved to a nearby dry dock in the next few years.

A survey of the ship's interior was carried out last month. Back outside, the news is mixed.

Much of the ship's exterior has been damaged by the elements

Mr Mills said: "Up near where the cover was protecting it, some of the original planking is quite good.

"But as you work your way down, that original planking starts to become quite decayed."

Even the "newer" planking, some which could date as far back as the 1850s, has extensive rotted sections.

Mr Mills said: "I'd say that it needs to be in the dry dock or repaired sooner rather than later.

"In all honesty, it's not helping the structure as a whole, to have all that amount of decay in it."

Shipwright Dominic Mills said much of HMS Unicorn is in original condition

After the surveys are complete, the data will be collated to give a complete picture of the ship's condition.

Lady Catherine Erskine, who chairs the Unicorn Preservation Society, said it was "vitally important" to know exactly where the ship's problems were ahead of its move to the nearby East Graving Dock.

Lady Erskine said it was a "crying shame" that the ship has not had the recognition it deserves.

She said: "I think everybody in Britain knows the Victory, and they know of the Mary Rose.

"Well, the Unicorn is of such significance.

Lady Catherine Erskine said it was a "crying shame" that Unicorn was not more recognised

"She's up there with those ships, but unknown, and a feature of Dundee for many many years."

Operation Safe Haven will see Unicorn moved to the dry dock where conservation work will continue.

There are plans for an accredited maritime heritage centre that would tell the ship's story.

The condition of its timber also has led to an unusual non-financial appeal from the preservation society.

The history of HMS Unicorn

HMS Unicorn was built in Chatham Dockyard in Kent

HMS Unicorn is the oldest ship in Scotland and one of the six oldest ships in the world.

The 46-gun frigate was built during peacetime and launched in 1824, spending its early life in reserve, anchored on the River Medway.

HMS Unicorn was moved to Dundee in 1873 to become a training ship for the Royal Navy Reserves.

It was almost scrapped in the early 1960s when Earl Grey Dock was filled in as part of preparatory work for the Tay Road Bridge.

After its move to Victoria Dock, the vessel was handed over to the Unicorn Preservation Society in 1968, and opened to the public in 1975.

Lady Erskine said: "I'm just asking the conservators for specifications of what we need, but ideally we will be getting people to gift us their enormous oak trees.

"Then we could get those milled and planked ready for the restoration work.

"We probably need to be cutting them down this year in preparation."

Lady Erskine said moving Unicorn to dry dock in time for its 200th anniversary would be "the best birthday present."

The latest work follows a survey of the ship's interior last month

Back outside, Dominic Mills and his colleague continue their meticulous work.

"I have worked on all of the old ships of this type, but this one is probably the most original, certainly inside," said Mr Mills.

"Virtually all of what you see dates back to the day it was built and it hasn't been largely rebuilt over that time.

"It really is a fantastic ship."

Photographs by BBC Scotland's Kris Miller