How Can Catamarans “Fly” Above The Water?

What makes catamarans able to take off and fly above the water? And is this at all intentional, when it happens during a race?

During sailing races, it is not uncommon to see catamarans fly above the surface of the water, sailing a long distance without the two hulls being in contact with the water. A catamaran is equipped with daggerboards – a type of right-angled wings, which reach into the water under the two hulls. As the catamaran gains speed, the water is forced to flow around the wing in such a way that a pressure difference is produced which is sufficiently significant to carry the boat’s weight above the water.

The daggerboards, which can be raised and lowered, are located around the centres of the two hulls. The aim of the crew is to steer the catamaran, so the hull avoids contact with the water surface, if possible. During America’s Cup, a catamaran can reach speeds of about 50 knots or some 90 km/h.