It was always amazing to me how old varnish has a way of making that edge look sloppy. A little overlap on deck along with the chipping on the old varnish edge can look bad. I used a rasor blade in a scraping motion to smooth the old varnish and to clean off any sloppy (no matter how small) areas or varnish that made it's way to the fiberglass attempting to get the cleanest straightest line between the deck and the wood first.

Once the wood to fiberglass edge is clean, smooth & straight careful tapeing and varnishing again make for a cleaner job. I like Toms comment on using the varnish as a seal. Perhaps thats why I always needed to use that blade to clean the line up.

As they say, good preparation is the key to a good job.

For me, if it looks good while your standing near it, it's good enough. We had wood handrails & eyebrows. They look good but varnishing them suck.