AddForceAtPosition to Parent's rigidbody...C#

So I have a few gameobjects(I'll call them floatpoints) as children of a Boat which contains a rigidbody.

My intent is that when the float points (which are constantly raycasting upwards) get below a terrain which I have re-purposed into an "on trigger", shifting, perlin-noisey, wave-infused ocean they will apply upward force/torque to their parent's rigidbody at the position of the floatpoints themselves effectively simulating the realistic pitch/roll of a boat floating amongst waves.

Here is the code in it's entirety...

         using UnityEngine;
         using System.Collections;
         
         public class RealisticFloat : MonoBehaviour {
         
             public float hoverForce = 5.0F;
             public float hoverDamp = 0.5F;
             void Start() {
                 rigidbody.drag = 0.5F;
                 rigidbody.angularDrag = 0.5F;
             }
             void Update() {
                 int layerMask = 1 << 8;
                 
                 
                 RaycastHit hit;
                 Ray upRay = new Ray(transform.position, Vector3.up);
                 if (Physics.Raycast(upRay, out hit, 500f, layerMask)) {
                     float hoverError = hit.distance;
                     if (hoverError > 0) {
                         float upwardSpeed = rigidbody.velocity.y;
                         float lift = hoverError * hoverForce - upwardSpeed * hoverDamp;
                         transform.parent.rigidbody.AddForceAtPosition(lift * Vector3.up, transform.localPosition, ForceMode.Force);
                     }
                 }
             }
         }

...Now I know the majority of this code works as I've had objects float around when it is referring to itself and simply doing a...

 rigidbody.AddForce(lift * Vector3.up);

...so I think the culprit is in this line...

 transform.parent.rigidbody.AddForceAtPosition(lift * Vector3.up, transform.localPosition, ForceMode.Force);

...I think I am either not accessing the parent's rigidbody correctly or using "transform.localPosition" for my vector3 is not working as intended.

The code compiles fine but when I start my game my boat just falls through the "Ocean" without so much as a wobble (the lack of wobble tells me it isn't a matter of applying insufficient force as the terrain is shifting constantly on the update).

The scripts are within the floatpoints themselves fyi.

I am at a bit of a loss and have been scanning documentation and similar questions for days. If anyone could shed some light on what I am doing wrong I would be extremely grateful.

also sorry for being so wordy but details = clarity...