Making buoyancy script not mass based

Hi everyone.

So I'm using this buoyancy script from the community shader project's ocean. As you can see it references the ocean and gets the water level where my object is to help calculate the forces.

My problem with it is that it seems to be very much based on the rigidbody mass. It is practically not functional if I set the mass to anything greater than 3. Of course, I want my object to respond realistically to other collisions and such, so I'm looking for a way to modify this script to make it no longer based on the mass of my object's rigidbody. I can't seem to figure out how.

The script: using UnityEngine; using System.Collections; using System.Collections.Generic;

 /* Give thanks to the Unity3d community, I'm just one of many to work on this.
  * http://forum.unity3d.com/threads/16540-Wanted-Ocean-shader
  * You are free to use this as you please as long as you do some good deed on the day fist usage.
  * Any changes and improvements you make to this, although not required, would be great
  * if at least shared with me (extra karma points if shared with the community at Unity3d).
  * This version has been optimized for mobile devices.
  * Ported to C# by Joaquin Grech joaquingrech@echoboom.es http://www.echoboomapps.com
  * Optimized a bit more to get extra FPS on mobile by MindBlocks team
  * Added realistic sinking method by MindBlocks team
  * */
 
 public class Boyancy : MonoBehaviour
 {
 
     private Ocean ocean;
 // Water plane at y = 0
     private float mag = 1f;
     private float ypos = 0.0f;
     private List<Vector3> blobs;
     private float ax = 2.0f;
     private float ay = 2.0f;
     private float dampCoeff = .2f;
     private bool engine = false;
     public bool sink = false;
     public float sinkForce = 3;
     private List<float> sinkForces;
     
     void Start ()
     {
 
         rigidbody.centerOfMass = new Vector3 (0.0f, -0.5f, 0.0f);
     
         Vector3 bounds = transform.FindChild ("Hull").GetComponent<BoxCollider>().size;
         float length = bounds.z;
         float width = bounds.x;
 
         blobs = new List<Vector3> ();
 
         int i = 0;
         float xstep = 1.0f / (ax - 1f);
         float ystep = 1.0f / (ay - 1f);
     
         sinkForces = new List<float>();
         
         float totalSink = 0;
 
         for (int x=0; x<ax; x++) {
             for (int y=0; y<ay; y++) {        
                 blobs.Add (new Vector3 ((-0.5f + x * xstep) * width, 0.0f, (-0.5f + y * ystep) * length) + Vector3.up * ypos);
                 
                 float force =  Random.Range(0f,1f);
                 
                 force = force * force;
                 
                 totalSink += force;
                 
                 sinkForces.Add(force);
                 i++;
             }        
         }
         
         // normalize the sink forces
         for (int j=0; j< sinkForces.Count; j++)
         {
             sinkForces[j] = sinkForces[j] / totalSink * sinkForce;
         }
         
     }
 
     void OnEnable ()
     {
         if (ocean == null)
             ocean = GameObject.FindGameObjectWithTag ("Ocean").GetComponent<Ocean>();
     }
 
     void FixedUpdate ()
     {
         int index = 0;
         
         foreach (Vector3 blob in blobs) {
             
             Vector3 wpos = transform.TransformPoint (blob);
             float damp = rigidbody.GetPointVelocity (wpos).y;
             Vector3 sinkForce = new Vector3(0,0,0);
             
             float buyancy = mag * (wpos.y);
             if (ocean.enabled && !sink)
                 buyancy = mag * (wpos.y - ocean.GetWaterHeightAtLocation (wpos.x, wpos.z));
             
             if (sink)
             {
                 buyancy = Mathf.Max(buyancy, -3) + sinkForces[index++] ;
             }
             
             rigidbody.AddForceAtPosition (-Vector3.up * (buyancy + dampCoeff * damp) , wpos);
 
         }
     }
     
     //Call this void when you want your boat or any object to sink more naturally
     public void Sink(bool isActive)
     {
         sink = isActive;    
     }
 
 
 }

Any help is greatly appreciated, thanks!