rotate gameobject on z axis with mouse x movement

I have looked at and tried everything posted but can’t seem to get anything to work. I have a boat controller that I steer with the mouse ( it’s basically the car controller with a TPS camera) I was able to get the boat to rise up with speed, but when I turn the boat with the mouse movement, I want the boat to tilt into the turn - along the objects Z axis. the script below works somewhat in that the boat tilts but up and down. I don’t want up and down or side to side I want it to tilt along its length to bank left or right

  var speed : float = 5.0; //how fast the object should rotate
  function Update(){
       transform.Rotate(Vector3(Input.GetAxis("Mouse X"), 0) * Time.deltaTime * speed);

wow that was simple, just add a minus sign

transform.Rotate(0, 0, -(Input.GetAxis(“Mouse X”)) * Time.deltaTime * speed );