Terrain Culled in RenderWithShader

I have an issue where my terrain is being culled inappropriately when used with a buffer I am constructing with the RenderWithShader functionality. The camera is created and then disabled immediately. Each frame I call this in OnPreCull:

Camera cam = shaderCameraObject.camera;
cam.CopyFrom (camera);
cam.backgroundColor = Color.black;
cam.clearFlags = CameraClearFlags.SolidColor;
cam.cullingMask = clipLayer.value;
cam.targetTexture = boatCullBuffer;
cam.RenderWithShader(shader, "CullBuffer");
Shader.SetGlobalTexture("_CullBuffer", boatCullBuffer);

So the camera has the same farClip as my main camera (I've debugged to confirm this). Here's a shot of the main camera's view:

alt text

And then here is a shot of the RenderWith Shader (Terrain should render completely green):

alt text

Any Thoughts? Why is the culling happening inappropriately?

your snippet is being called on the OnPreCull? the RenderWithShader function doesn't calls OnPreCull http://unity3d.com/support/documentation/ScriptReference/Camera.RenderWithShader.html so your CopyFrom is probably not being applied. Try calling it from somewhere else.

Edit: Ooops, nm I misread the question sorry