A tidal turbine blade

A caudal fin shaped blade for use on a horizontal axis tidal current turbine is designed by bio-mimicking the Blue Marlin fish caudal fin. A method for forming the blade includes the steps of defining a traditional horizontal axis tidal turbine using a symmetrical airfoil comprising nine airfoil stations placed at 10 percent of the blade, determining a twist angle distribution by creating a twist angle distribution rule for root airfoil and tip airfoil and using a third order polynomial function passing through the centre of each airfoil to twist the blade from root airfoil to tip airfoil.