Crisping up the transom edge

You ask what this title is about?   When the hull was fiberglassed, you needed to round the edges of all corners so the glass cloth could lay smooth.  A sharp edge cannot be fiberglassed because a bubble would form at the corner as you tried to bend the cloth around it.  So, prior to setting the cloth, all the sharp corners were smoothed, either via a router or hand plane and sanding.
This is not a problem except at the bottom of the hull at the transom.  The rounded edge will cause turbulence when the hull is planing.  The designer recommends that the edge where the bottom meets the transom be turned into a crisp edge so the water releases cleanly when on plane.  
To accomplish this, I needed to build up the rounded corner with epoxy resin mixed with cabosil to make an epoxy paste that would hold to a form.  I used some scrap plywood covered with plastic tape to make a dam on the transom.

Here you can see the plywood attached to the transom. Please note that the duct tape does not work for this application.  I used a hot glue gun and a series of glue spots to attach the wood to the boat.  The tape was just to hold it for positioning.  The hot glue is a woodworkers trick to temporarily fasten two pieces.  If used sparingly, the pieces can be separated with no damage and easily cleaned up.  I then applied the epoxy mixture in the crack between this dam and the bottom.
After it hardened, I sanded it smooth along the bottom and transom to create a crisp edge.  Here is the result:

It isn't real clear in the pictures, but the edge is pretty clean and sharp.