As a result of an unanticipated run in with an uncharted underwater obstruction, we lost an approximate 4" square piece from the bottom front edge of our Foss Foam rudder. I am familiar with the West epoxy system which can be used for the repair. My questions are (1) what can I use to fill the 4" square void (thickened epoxy or maybe auto putty are all I can think of), (2) how do I attach the filler to the existing rudder (i.e. stainless steel dowels embedded and epoxied to the existing rudder) and (3) how do I maintain the shape of the filler (especially if I use thickened epoxy) until I can glass over the filler. Any thoughts would be appreciated.