Sailing in the area of the Race, there are a lot of cross currents. Setting a waypoint and then using the rhumb line for guidance keeps you going where you want - which is sometimes quite far from where the boat is pointed. This increases my confidence in my ability to avoid the local hazards, and as a result, I find myself using routes that I wouldn't use without the chartplotter - ie: a route through the Sluiceway rather than E of Little Gull or through Plum Gut.