On Long Island my experience is that by in large ducks don't fear white boats, especially if you doing something else. For quite a few years I would camo cover my Carolina Skiff in an effort to "hide" and it worked well. But then I noticed that when clamming or just hanging out, the birds went directly overhead. No worries at all. After that I started just drifting along the banks or through some of the marsh creeks and had great success pass shooting.
Other times I would drop off the decoys and anchor the boat 100 - 150 yards away, downwind if possible so the birds didn't see the boat and decoys at the same time and shoot from a ground blind. Both approaches were very productive for Blacks, Mallards, Brant and the occasional goose.