A wave energy converter comprising: a shell being a floating body extending along the surface of a body of water and moving generally in phase with waves therein, and a non-circular column; said shell and column being spaced apart to permit the shell and column to move up and down relative to each other when placed in the body of water and in response to the waves present in said body of water; and a power take off (22, 24) device connected between the shell and the column to convert the relative vertical motion between the shell and column due to the waves into electrical energy; characterized by: the shell having an outer wall and a central opening with a non-circular inner surface shaped to conform to the non-circular outer surface of the column for the positioning therein and passing therethrough of said non-circular column, said non-circular column extending through the shell above and below the shell; and the said non-circular column positioned within, and extending along, the central opening of the shell, the non-circular inner surfaces of the shell and the non-circular outer surfaces of the column being formed and shaped such that, when placed in a body of water and in response to waves in the body of water, rotational and/or twisting motion between the shell and the column is inhibited while the inner surfaces of the shell and the outer surfaces of the column are spaced apart and extend along parallel spaced apart planes to permit unhindered vertical up and down motion of the shell relative to the column. a shell being a floating body extending along the surface of a body of water and moving generally in phase with waves therein, and a non-circular column; said shell and column being spaced apart to permit the shell and column to move up and down relative to each other when placed in the body of water and in response to the waves present in said body of water; and a power take off (22, 24) device connected between the shell and the column to convert the relative vertical motion between the shell and column due to the waves into electrical energy; characterized by: the shell having an outer wall and a central opening with a non-circular inner surface shaped to conform to the non-circular outer surface of the column for the positioning therein and passing therethrough of said non-circular column, said non-circular column extending through the shell above and below the shell; and the said non-circular column positioned within, and extending along, the central opening of the shell, the non-circular inner surfaces of the shell and the non-circular outer surfaces of the column being formed and shaped such that, when placed in a body of water and in response to waves in the body of water, rotational and/or twisting motion between the shell and the column is inhibited while the inner surfaces of the shell and the outer surfaces of the column are spaced apart and extend along parallel spaced apart planes to permit unhindered vertical up and down motion of the shell relative to the column. the shell having an outer wall and a central opening with a non-circular inner surface shaped to conform to the non-circular outer surface of the column for the positioning therein and passing therethrough of said non-circular column, said non-circular column extending through the shell above and below the shell; and the said non-circular column positioned within, and extending along, the central opening of the shell, the non-circular inner surfaces of the shell and the non-circular outer surfaces of the column being formed and shaped such that, when placed in a body of water and in response to waves in the body of water, rotational and/or twisting motion between the shell and the column is inhibited while the inner surfaces of the shell and the outer surfaces of the column are spaced apart and extend along parallel spaced apart planes to permit unhindered vertical up and down motion of the shell relative to the column.