Wind farms are a familiar sight off the coast of Britain, but what goes into maintaining them? At Westermost Rough, in the North Sea, a team of workers are tasked with ensuring 35 gigantic turbines keep generating electricity.

That involves climbing the turbine towers almost 300ft (90m) high above the water, as the BBC discovered when we joined workers on a voyage to the site about five miles from Withernsea, East Yorkshire.

When we set out on a crew transfer vessel from Grimsby docks on a bright October morning, the sea is unusually calm.

"It's like a sheet of glass," says our pilot Peter Gracey as he looks out across the calm sea.

Westermost Rough is operated by Orsted and can generate enough electricity to power more than 180,000 homes.

As we approach heading north from Spurn Point, at the tip of the Yorkshire coast, the turbines are standing still.

The lack of wind means the blades are idle, but for maintenance crews it is close to perfect working weather.

In the distance, another bright yellow crew transfer vessel can be seen moving between turbines, ferrying engineers from one maintenance job to the next.

Days like this are prized by crews. Calm seas make it easier to transfer workers safely from vessel to turbine and mean engineers can carry out inspections and repairs that might otherwise have to wait.

Sam Torrance is among the technicians who carries out these tasks.

A former apprentice from Healing, near Grimsby, he has worked for Orsted for the past seven years.

For Torrance, the job is equal parts detective work and engineering.

"I'm a troubleshooter," he says. "The office will tell me something's broken and I have to go and find out why it's broken and I'll go and fix it."

The work often starts long before he reaches the turbine itself. Modern offshore wind farms send a stream of data back to shore, reporting everything from power output and wind speeds to pressure readings and fault codes.

"We get a lot of feedback," he explains. "The turbine will send fault codes, it'll send pressures, it'll send what the wind speeds are and how much electricity it's producing."

Staff back at base use the data to prepare Torrance for the maintenance work.

"They might pick me 20 parts or 100 parts. I might end up only needing one of them."

During the summer months, crews race to complete servicing programmes before rougher weather arrives.

"You don't want to fall behind over the winter," he adds.

As our Windcat vessel approaches one of the turbines, Gracey manoeuvres it into place.

Able Seaman David Higgins then oversees the transfer of technicians from boat to turbine – a process governed by strict safety procedures.

"It's almost like a taxi service, which is why it's called a crew transfer vessel," Higgins says.

The engines push the vessel firmly against the turbine's access ladder, holding it securely in place. Torrance and his colleagues then attach themselves to a fall-arrest system before beginning the ascent to a work platform.

On a calm day, the transfer looks straightforward. In rougher weather it can be anything but.

"If there's any big waves you would stop everything until it's clear," Higgins explains.

Once aboard the platform, crew members face a trip to the top of the turbine tower, helped sometimes, but not always, by a built-in lift.

For Torrance, having to climb up can be one of the most physically demanding parts of the job.

"It's exhausting," he says. "Your lungs burn. The air is thick. If the lift is out of use, it's a bad day."

Tools and equipment are lifted up to the turbine by crane before technicians begin diagnosing faults, replacing components or carrying out planned servicing.

Despite the pressure to return turbines to service, Torrance says there is no pressure to cut corners.

"The job takes as long as it takes," he adds.

Westermost Rough is approaching the midpoint of its estimated operational life. It was designed to operate for 25 years and was the first in the world to make commercial use of Siemens 6MW offshore wind turbines, with components built in Hull.

Three other wind farms, Hornsea 1, 2 and 3, have been constructed nearby, but in 2025, Orsted decided to "discontinue" Hornsea 4, which would have been one of the country's largest, saying it no longer made economic sense.

In August this year, the company said it was "evaluating options for future development" at the site.

In January, the government awarded contracts to build a record amount of offshore wind around the UK, arguing that these projects are cheaper than new gas power stations and will "bring down bills for good".

However, at the time, the Conservatives said climate targets and increasing costs in the sector were raising energy prices.

The way engineers work could also change in the years ahead.

Last week, Orsted announced successful trials of large cargo drones, capable of delivering tools and spare parts directly to offshore turbines, potentially reducing lifting operations and helping maintenance teams respond more quickly.

For now, however, offshore wind still very much depends on people like Torrance.

As the vessel returns to Grimsby at the end of the day, he reflects on an industry that has shaped his own career and, to some extent, the Humber's economy.

"It's rewarding at the end of the day," he says. "Amazing to be a part of."