Power generating apparatus

Disclosed herein is a power generating apparatus for extracting energy from flowing water. The apparatus comprises a buoyancy vessel, and a turbine assembly coupled to the buoyancy vessel which comprises a turbine rotor mounted to a nacelle, and a support structure. The turbine assembly is pivotally moveable between a first position and a second position. When the power generating apparatus is floating on a body of water, in the first position the nacelle is fully submerged below the water surface; and in the second position at least a part of the nacelle projects above the water surface. Movement of the turbine assembly from the first position to the second position is buoyancy assisted, for example by providing the turbine assembly with positive buoyancy or selectively increasing its buoyancy. Movement of the turbine assembly to the second position may be desirable to reduce the draft or the drag of the power generating apparatus, for example when the power generating apparatus is being relocated, or to prevent damage during storms. In addition, when in the second position it is possible to gain access to the nacelle for maintenance or repair.