Abstract: A formwork for a draft tube which includes ganged precast forms, each precast form corresponding to a curved segment of the draft tube. The precast forms are molded with continuous side plates extending thereabout and anchored in the precast concrete form and projecting beyond the surface opposite to the contact surface to provide a flange. A fastening means for attaching adjacent forms with a space therebetween to allow for stripping. A method includes determining the outline of the inner surface of the draft tube and dividing it into segments and preparing molds to make precast forms corresponding to each segment. The precast forms are assembled and shored to provide the draft tube ganged formwork, and concrete is poured about the draft tube formwork and is cured. The precast forms are stripped from the set concrete structure and reused in another draft tube formwork.