Extract of energy from the sea

Apparatus for extracting energy from waves in the surface of a body of water, comprising a structure moored in and floating in the body of water and having an inlet channel disposed to face into oncoming waves;

• and means for converting the energy contained in water entering the inlet channel as a result of the wave motion, to a transmittable form, said means comprising an air chamber in the form of an elongate spiral passage having a passage at one end, in communication with a downstream part of the inlet channel and having an air inlet and outlet at the other end, a rear outlet from the downstream part of the inlet channel, and valve means operable, in response to water flowing into the channel, to close suddenly the rear outlet and cause that water flowing into the channel to enter the chamber and pressurize air in the chamber whereby to enable the pressurized air to be taken from the air outlet from the chamber to do useful work.