The rudder consists of a pair of slightly conical (usually but not always - designs vary), semi-cones mounted on a pivot either side of the propeller with the long axis of the cone running fore and aft when the helm is midships.
The rudder comprises a pair of slightly conical (typically but not necessarily - designs differ), semi-cones positioned on either side of the propeller, attached to a pivot when the helm is centered. The long axis of each cone runs fore and aft.