I've not been looking forward to using glass mat over the edge of the hull & transom as glassing over a 90 degree bend is tricky at best and impossible at worst. Even with a lightweight cloth the mat tends to lift adjacent to the corner and form an lump & air bubble that has to be sanded away and completely negates the reason for putting glass mat on in the first place.

Now, according to most of the sources I've read recently, the glass mat is not purely there for additional strength but also to hold the epoxy in place while it cures. Without the glass mat the epoxy sags away under gravity.

So, the recommended way to deal with a right-angled corner is to take a round over bit in a router or to use a rasp and round over the angle by about 6mm so that the sharp corner no longer exists. Then you mix up some epoxy and thicken it with a filleting blend or colloidal silica to form a stiff paste and apply that to the rounded over corner so that the corner is rebuilt in epoxy. The corner is sanded after the epoxy has fully cured to give a nice sharp edge again and to make it flat and inline with both sides. 

The glass mat is then applied to both faces but only up to the edge of the corner on both side and not over it. No lumps and no air bubbles.

With the case I have making this epoxy fillet is all that is required as I'm trying to ensure that there are no holes or cracks in the epoxy under the reinforcing pads which might allow water to get through the leak again. The glass mat was only there to hold the epoxy in place and not having to use it is a definite plus point.

And this is the result so far. After ensuring that the copper epoxy have been properly cleaned, the edges of the reinforcing pad were cleaned of excess hardened epoxy with a sharp chisel and the hull & transom adjacent to the pad were similarly treated. I then applied neat epoxy to any exposed wood on the pad and left it a while to soak in a bit.

The remaining epoxy was thickened with filleting blend to make an epoxy paste with the consistency of cold peanut butter and this used to form a fillet around the pad using it liberally on the edges of the pad that would be underwater. Once this is cured to a green state I'll trim some of the excess off with a sharp chisel and then, when it is fully cured I'll sand the epoxy to a nice finish.

Talking of sanding, this is part of the hull that I've sanded using a random orbital sander. All of the remaining green growth has been removed and the remaining green is copper verdigris the copper equivalent of rust on steel. There's no need to sand it any more than this except in the areas where I need to touch up the copper epoxy.

I did try sanding a bit by hand but it was a bit too aggressive and removed too much of the copper epoxy. I'll go back to the orbital sander when the time comes to sand the hull. I'll need to buy some more sanding pads before I do that as I've not got enough to do the job.

Time for a cup of tea.

After I had let the epoxy cure a little I went back with a fresh mix of epoxy and some peel ply. The peel ply in this instance served two purposes.

The first was to allow a ready to coat surface once the peel ply was removed...

...and the second was to allow me to smooth out the lumps and bumps in the epoxy to give a better finish. I laid the strips onto the epoxy and used a finger to press it down into the surface a little and then ran my finger over the peel ply, applying a little pressure to smooth out the epoxy underneath. I applied the neat epoxy onto the peel ply such that the epoxy underneath was covered.

Hopefully this will result in a nice finish. I'll see how it comes out tomorrow.

Time for (another) cup of tea.