Make Cube's Volumetric Grid Respond to Rotation

I am currently working on a Buoyancy System(starting with basics) using the suggestion given here: http://answers.unity3d.com/questions/11825/how-can-i-implement-physics-objects-which-float-in.html

I am at the point where i have made a 'Volumetric Grid' and am averaging the positions of the underwater points(Which works), but i have one problem:

It doesn't work with rotations. How can i get the grid to work with rotations(Code Below)?

*EDIT: Also is their a better way for me to create a 'Volumetric Grid'?(would using mesh verticies be better?)

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class Buoyancy : MonoBehaviour {
 
     private float WaterLevel;
     private VolumePoint[] VolumePoints;//Are points underwater or not?
     private Vector3 ObjScale;
     private Rigidbody rBody;
 
     private float forceToApply;
     private Vector3 PointToApplyForce;
 
     private List<VolumePoint> tempVolumePoints;
 
     void Start() {
         ObjScale = transform.localScale;
         CreateVolumetricGrid();
     }
 
     void Update() {
         UpdateVolumetricGrid();
         GetForcePoint();
     }
 
     void LateUpdate() {
 
     }
 
     void CreateVolumetricGrid() {
         tempVolumePoints = new List<VolumePoint>();
 
         for (float z = -ObjScale.z / 2f; z <= ObjScale.z / 2f; z += .25f) {
             for (float y = -ObjScale.y / 2f; y <= ObjScale.y / 2f; y += .25f) {
                 for (float x = -ObjScale.x / 2f; x <= ObjScale.x / 2f; x += .25f) {
                     tempVolumePoints.Add(new VolumePoint(new Vector3(x, y, z)));
                 }
             }
         }
 
         VolumePoints = tempVolumePoints.ToArray();
     }
 
     private void UpdateVolumetricGrid() {
         foreach (VolumePoint point in VolumePoints) {
             if (transform.position.y + point.pointOnObj.y < 0) point.isUnderWater = true;
             else point.isUnderWater = false;
         }
     }
 
     private void GetForcePoint() {
         Vector3 Average = new Vector3();
         int points = 0;
         foreach(VolumePoint point in VolumePoints) {
             if (!point.isUnderWater) continue;
 
             Average += point.pointOnObj;
             points++;
         }
         Average /= points;
         PointToApplyForce = Average;
     }
 
     void OnDrawGizmos() {
         Gizmos.color = Color.magenta;
         Gizmos.DrawWireCube(transform.position, transform.localScale);
         
         if (VolumePoints == null) return;
         foreach (VolumePoint point in VolumePoints) {
             if (point.isUnderWater == true) Gizmos.color = Color.green;
             else Gizmos.color = Color.red;
             Gizmos.DrawCube(transform.position + point.pointOnObj, new Vector3(.01f, .01f, .01f));
         }
 
         Gizmos.color = Color.yellow;
         if (PointToApplyForce != Vector3.zero) Gizmos.DrawCube(transform.position + PointToApplyForce, new Vector3(.2f, .2f, .2f));
     }
 
 }
 
 public class VolumePoint {
     public Vector3 pointOnObj;
     public bool isUnderWater;
 
     public VolumePoint(Vector3 _pointOnObj) {
         this.pointOnObj = _pointOnObj;
     }
 }