Just published this:
One of the challenges we face by trying to sustainably pace ourselves is that a job like fitting the new bow roller takes quite a few visits to the boat. However, we think the process of filling from the new backing plate to deck level using scraps of FR4 with thickened epoxy is a little novel.
This is an area that just need to be strong in compression (sandwiched between the backing plate and the bow roller). FR4 is ideal here as we will never need to worry about water ingress through the bolt hole causing rot. It is a lot quicker (and better in compression) than building up with layers of fibreglass. We don’t need to worry about cosmetics as this part is going to be completely buried. Nor do we need to worry about a smooth finish on top as it will be covered by a larger FR4 board that will be bedded with more thickened epoxy. This board will also include raised bases for the forward pulpit feet to keep them drier.
Later we will create the curve at the aft end with a small wood batten and then the whole lot will be encased in fibreglass cloth to fully tie it to the bulwarks and give us a surface to fair up before painting.
Sustainable Sailing 