For 40 years she has been synonymous with taking Glasgow families "doon the watter".

And later this month the Waverley - the world's only sea-going paddle steamer - will celebrate her ruby anniversary in style.

Since May 1975, when she started sailing in preservation under charity status, Glasgow's favourite ship has taken more than five million passengers up and down the west coast of Scotland and beyond.

To celebrate this special occasion, on 21 May the firm that runs the ship, Waverly Excursions, is hosting a special reception for the hundreds of volunteers, supporters and enthusiasts who have helped the ship stay afloat through rocky financial waters over the last 40 years. Among the guests will be Glasgow Lord Provost Sadie Docherty.

Later that evening, passengers will have the chance to sail down to Greenock to see off another grand sea-faring vessel, the QM2, and watch its spectacular fireworks display.

Three days later, 40 years to the day since the Waverley first left Glasgow in its new role, that day's 1975 timetable will be replicated, with a classic route that takes in favourite spots including Largs, Rothesay, Tighnabruaich, Tarbert and Loch Fyne.

It's going to be a particularly special time for this most special of ships, and no one is looking forward to it more than the woman whose job it is to keep her sailing, chief executive Kathleen O'Neill.

"People know what the Waverley is and have a great affection for her," says Kathleen, as she gives the Evening Times an exclusive behind the scenes tour of the ship as she is spruced-up for the season ahead. "For many, she reminds them of her childhood - there is a real nostalgia value there.

"Her attraction lies in a mix of things - the heritage, social history, maritime history, engineering history, the scenery. But I think more than anything, it's just about having a great day out."

That the Waverley has managed to keep sailing for so long is an achievement in itself. It's partly down to the support of enthusiasts, including high-profile fans such as EastEnders actor Timothy West and his wife Prunella Scales, who are regular passengers.

Kathleen admits keeping a vintage ship sailing is an expensive business, especially in these days of high fuel, insurance and compliance costs.

"We are lucky that ports in Glasgow, Argyll and Bute and Inverclyde give us free berthing," she says. "But it costs £12,000 a day to run the Waverley on the Clyde. That's a huge amount of passengers to get up the gangway. The pressure is on most of the time and we can't always make the money to cover the costs."

One thing that can't be controlled is the weather, and according to the ship's captain, Senior Master Andy O'Brian, it can have a big impact on the ship's success.

"Sailing the Clyde is very difficult on a ship like this," says Andy, 49, from Gourock, who started his sailing career at 16 as a gangway boy. "The weather affects us far more than it does the ferries. But the satisfaction comes in doing the job well. And you also get to sail in some wonderful places."

Maintenance costs are kept down by the ship's committed team of volunteers and the services of young apprentices donated by City Building and BAE systems.

Former Rolls Royce engineer Gordon Johnstone, 83, from King's Park, has been volunteering for seven years.

"I just love going doon the watter," he smiles. "And volunteering is a good chance for me to pass my skills on to others. To see the Waverley still sailing after all these years is fantastic."

At the other end of the age range is City Building painting and decorating apprentice Gemma Wright, from Riddrie.

"I enjoy coming to work every day," she explains. "And my granddad was so excited when I told him I was going to be working on the Waverley. It's amazing to work on something so iconic."

Sidebar

The Waverley is the world's last sea-going paddle steamer. She was launched in 1946 from the A&J Inglis yard, on the site of the Riverside Museum, and towed to Greenock where her triple expansion steam engines were fitted by Rankin and Blackmore.

Originally operated by the London and North Eastern Railway, she was designed for pleasure excursions from Craigendoran to Lochgilphead and Arrochar.

In 1974, at the end of her working life, the vessel was bought for £1 by the Paddle Steamer Preservation Society and taken into charitable status. Her first sailing in preservation was on 21 May 1975.

Since then the ship has carried more than five million passengers from 80 ports around the British Isles. She has also been voted Glasgow's Favourite Tourist Attraction.

In 1977, the Waverley grounded on rocks off Dunoon, which almost led to her total loss. She was rescued by heavy pumps provided the US Navy stationed at Holy Loch.

Between 2000 and 2003, the ship was virtually rebuilt in Great Yearmouth with the help of more than £3 from the Heritage Lottery Fund and grants from local authorities, Scottish Enterprise and the European Union. The work returned to the ship to her 1940s glory.

In 2011, EuroMillions lottery winners Chris and Colin Weir, from Largs, stepped in to keep the ship going when it faced financial crisis.

Today the ship receives funding assistance from the Paddle Steamer Preservation Society, Glasgow City Council, Inverclyde Council, Argyll & Bute Council, North and South Ayrshire Councils.

As well as providing pleasure cruises, the Waverley also has its own skills academy, where people from all over the world come to train in the unique maritime skills needed to sail the ship.