North Sails tests the world’s largest sail

The A2 sail – a light-wind spinnaker generally used for racing – was made for the 59-metre-long superyacht Perseus^3 and measures just over 2600 square meters in area.

The sail took 10 sailmakers and two graphics installers 15 days to make. It was tested for the first time last week.

“The boat was specifically looking for a target area from a rating perspective, so the design was driven by that,” North Sails engineers Glenn Cook said. 

“And because Perseus^3 is a huge boat, you can’t turn very quickly and trimming adjustments are also slow, so we looked to make a sail that had a very stable flying shape. 

“Plus the sail has to work across a variety of conditions; the design is more forgiving than you would do on a smaller sail.”

The sail was built with a long luff – the leading edge of the sail – meaning it could drop into the water when gybing. However, Cook said North Sails had developed a system above the tack to collect the sail while gybing and keep it clear of the water.

One of the challenges the team faced was ensuring the A2’s grey colour was consistent across the sail.

Contender Sailcloth USA president Duncan Skinner said matching the spinnaker’s grey colouring took the longest time because that amount of material could not be dyed all at the same time. 

“The machines just aren’t that big,” Skinner said. “You have to pay a lot of attention to the dye formulation and to the timing… and when you look at the kite, it’s pretty damn close.”

The spinnaker is made from Superkote 350 nylon fabric that weighs around 150 grams a square metre, with the entire sail weighs around 550kg. The material includes a bit of stretch so that shock loads are not transferred directory to the rigging or the hull.

Just dragging the A2 around the deck needs between 10 and 15 people, Cook said.