The loads on both a model of a smooth cable and a helical strake (also known as scrouton spiral) were measured in a wind tunnel. The coefficients of drag, lift and transverse force were ascertained for an angle of attack between 0 and 360 degrees. Results show that the drag coefficient increases by the spiral in each case whereas the lift coefficient changes only insignificantly. A defined transverse force is caused by the spiral. To find an explanation of this force by the circulation a simple mathematical model is given. Finally the behaviour of a twisted rope in water calculated by a known code is predicted in case of steady current.

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