The crank shaft is rotating Clockwise when viewed from above, Newtons 3rd Law, For every action there is an equal and opposite Reaction. In this case the Block will try to rotate Counter Clockwise. This will push the rear of the prop to starboard which pushes the stern of the boat to Port and the bow will point to Starboard. The rotation of the prop is also making the motor rotate in that direction as well. In addition an engine trimmed in close to the transom will also result in making the engine swivel in that direction as well, if trimmed out from the transom, there will be a point where the forces are balanced, then further outward trim will cause a pull to Port.
There is a Friction Adjustment on the swivel bracket that can be adjusted to keep the engine from turning on its own