The Sills siblings do their training at Roadford Lake in Devon
Cornish windsurfer Saskia Sills has added to her Under-15 world title by winning gold at the U-15 National Championships in Weymouth.
The 13-year-old from Launceston proved herself as the UK's top windsurfer in the 6.8 Techno class last week.
In August, Sills also won gold at the World Junior Championships in Weymouth, finishing just one place ahead of her twin sister Imogen.
The sisters train at Roadford Lake, on the border between Devon and Cornwall.
The twins' older brother, Sam, is also a world champion windsurfer.
He won gold in the Techno Under-17 boys' division at the World Championships in August.