Awesome engineering lures crowds to Lock 18

Just like people, canals need care and attention as they age. This year, three canal locks at Seend, near Devizes, were restored and given a new lease of life by our team to get them ready for the busy boating season ahead.

Installing fabric dam at Lock 17 - Image courtesy of Richard Holden

Working hard through the bitter winter, a team of skilled craftsmen repaired locks 17, 18 and 19, which were all built between 1794 and 1803. On March 10, the charity invited the public to venture into lock 18 and discover the challenges of repairing our historical structures.

More than 700 people turned out to view the incredible engineering that took place, while George III was on the throne, in this quiet spot in the middle of the Wiltshire countryside. And to celebrate the wonderful Kennet & Avon Canal.

They took part in many activities including crafts aboard The Admiral Welcome Boat, watching our virtual reality video of canal locations, trying their hand at bricklaying and building bird boxes, yarn bombing, viewing a tankful of canal fish and listening to poetry readings.

Apprentice Sam Pointer helps Keith Burgman with bricklaying - Terry Hewlett

A spectacular lock 

Canal Laureate Nancy Campbell paid a visit and said: "Sometimes when I write a poem about canals I come at it from a sideways angle. By putting on all these activities you can reach people with a range of interests so they too can discover the canal in their own way.”

The spectacular lock is five metres (16.4ft) deep and was constructed from Bath stone and brick. Ali Harper from Devizes said: “I’ve sailed over this lock and it’s alarming to see how deep it is.”

Guests were impressed with the accuracy with which the stones are fitted. Nancy was moved by the stone’s texture and age. "It’s the first time I’ve been to the bottom of a lock and it gives a sense of hidden histories stretching back to the industrial revolution."

We are spending £281,000 on the three locks, built by engineer John Rennie. Visitors admired the new lock gates towering at both ends of lock 18. Each pair of oak handmade gates cost between £15,000 and £21,000 and each of the larger bottom gates weighs almost three tonnes. They have a lifespan of 20-25 years and are lifted into place by crane.

Team leader Ray Humphry installed their predecessors in 1996. “I’m proud to be replacing them again - I’ve fitted about 150 pairs in my time. Fundamentally the techniques haven’t really changed over the years,” he said.

A lock stoppage on average takes five weeks to complete. "We have a sense of anticipation each time we drain a lock wondering what problems we will face. This time we had to remove about 70 tons of silt to uncover the stone floor in this lock," said Ray.

As it happened the floor was almost pristine but work was needed on the chamber walls and other areas. "Among our many tasks, we repaired the brickwork above the waterline with traditional lime mortar, but used sand and cement beneath. We cut reclaimed Bath stone to size and used the blocks to repair the quoins – getting the gates to sit well against them is always a tricky job. The gates themselves come with more steel reinforcement these days and are better made, so they leak less," said Ray.

Impressive bottom lock gates - Terry Hewlett

Wonderful volunteers

Waterways Manager Mark Evans said: "The feedback we had has been incredibly positive and it was probably the best open day we’ve held - everyone pulled together. Of course, it could not have happened without the help of our wonderful volunteers, who supported us in all aspects.”

Canal & River Trust is spending £38 million on maintenance across waterways in England and Wales. TV presenter Paul Martin came to see the lock and commented: “This lock is an example of awesome engineering. It’s so important to look after this heritage because once it’s gone, it’s gone for ever. It’s really important for everyone to get involved with looking after the canal. There are so many lock gates on this stretch, which are expensive to replace, so please support the Trust if you can."

Susan Litherland, Canal & River Trust 

Last date edited: 9 October 2018