Hi

It is better to cut away more than just the rotten wood, so a new piece
glued with Epoxy will carry the loads ------- even with a bad fit it is
better to replace the bad wood with new and _then use the Epoxy to what
it is perfect for, as glue. What's so good about Epoxy is just that
even a bad fit don't matter that much as with other glues ,in fact I
think, it is often better to replace the rotten wood with Epoxy rather
than even thinking about using it as reinforcement for epoxy. With spot
repairs it is also better to have a hand router with a copy ring and a
few standard patches that fit with the router template.
Use Epoxy like that and the repairs will last longer than the boat.