We were heading back from St Johns, NB to Maine when this funny stuff showed up on radar - the Foxes. We had no paper chart that showed them so we just gave them a wide berth. This was pre-chartplotter, and I thought we had the charts we needed for where we were going. I was wrong - fortunately we avoided trouble.
Curious how all the maps of Maine don't show Grand Manan. It's closer to Maine than Block Island is to Pt Judith - selective mapping??
In the long run, you're on your own out there. Plan the best you can, then sail the plan - being ready for surprises. The alternative is to just go - then everything is a surprise.