In pictures: America's Cup racing in Portsmouth

The America's Cup has been dubbed "Formula One on foils"

The latest round of America's Cup World Series takes place in Portsmouth this weekend, with practice races under way on Friday.

The series is a collection of regattas leading up to the 35th America's Cup in Bermuda in 2017.

Sir Ben Ainslie is hoping to lead the first British team to win the overall competition.

The six competing catamarans, powered by huge sails, are capable of reaching speeds of 40mph (64km/h).

The six competing teams began practice races on Friday

The catamarans, powered by huge sails, are capable of reaching speeds of 40mph (64km/h)

The race dates back to 1851 when a group of US businessmen visiting for Prince Albert's Great Exhibition challenged a British sailing team to a race around the Isle of Wight.

The 34th America's Cup was held in 2013, when an American team advised by Sir Ben Ainslie overcame an 8-1 points deficit to Team New Zealand to clinch a dramatic victory in the last of 17 races.

Sir Ben Ainslie hopes to lead the first British entry in the main America's Cup event since 1964

Sir Ben Ainslie's Land Rover BAR team is the first British entry in the Challenger Series, which precedes the main event, since 2003.

He is hoping to win in Portsmouth for a second year running to earn points towards the finals in Bermuda next year.

The Red Arrows gave a display for large crowds in Portsmouth

The Red Arrows flew over a large crowd on the shore-line on Friday.

The Duke of Edinburgh, in his role as Admiral of the Royal Yacht Squadron, was in Portsmouth for the races.

The Duke of Edinburgh was in Portsmouth to watch the racing