MouseY movement

Hi I would like to move my ship towards the Y axis of the mouse, i've checked the game input to mouseY

So far I have the code pasted below. Also a screenshot to elaborate this issue I have an object with no rotation but the camera is rotated -90 to show a side view. I have no gravity selected.

The top and bottom of the ship are in the scene editor 1.4 and -1.4 ( aka the min & max a ship could move thus its boundaries )

However the ship never reaches my max or min point as you can see in the screenshot. Its like it has a sort of delay or offset.

I am new to unity, i have many years of AS3 knowledge but awkwardly new to unity, but loving it! and so far I can't seem to bend my head around it. Thank you!

 using UnityEngine;
 using System.Collections;
 
 [System.Serializable]
 public class Boundary
 {
     public float xMin, xMax, zMin, zMax, yMin, yMax;
 }
 
 public class PlayerController : MonoBehaviour
 {
     public float speed;
     public float tilt;
     public Boundary boundary;
     
     void FixedUpdate ()
     {
         float moveHorizontal = Input.GetAxis ("MouseY");
         //float moveVertical = Input.GetAxis ("Vertical");
         Vector3 movement = new Vector3 (0.0f, moveHorizontal);
         rigidbody.velocity = movement * speed;
         
         rigidbody.position = new Vector3 
             (
                 0.0f, 
                 Mathf.Clamp (rigidbody.position.y, boundary.yMin, boundary.yMax), 
                 0.0f
                 );
 
         rigidbody.rotation = Quaternion.Euler (0.0f,0.0f, rigidbody.velocity.y * -tilt );
     }
 }

![alt text][1] [1]: /storage/temp/27392-screenshot-2014-06-06-22.49.25.jpg