I assume you mean, in reverse, the stern does not go to starboard...An engine in reverse creates prop walk to port...thus your experience. Prop walk is a weak effect. When you have adequate water flow past the rudder, say moving 1+ knots, your rudder to starboard can override the prop walk effect allowing you to control the direction of the stern. If the stern gets out of kilter, ie too far to port, your solution is apply hard left rudder and a short burst of power in forward. This shot of prop wash on the rudder will swing the stern back to starboard. Repeat if required. Then resume your maneuvering in reverse...but you need to get the boat moving if you want the rudder to effect its rotation.