I've not sailed (or even been there) in Maine, but I've heard it described as being similar to the PNW where we are with many islands and straits and channels, and poor visibility at times. When the weather is clear and you are in a fairly large body of water paper charts and a handheld are more than adequate, no question. When things get dicey is when a chartplotter pays for itself many times over. I can't tell you how many times I've approached, or been in the middle of, an unfamiliar area in less than ideal conditions and have gotten turned around in my directions from just looking at the paper charts (and in some cases I've also had the radar on as well). Fog is a whole other can of worms. Can it be done with just paper charts, of course, and with the addition of a handheld GPS there is no question you will get where you are going (and back), but the addition of a small chartplotter adds considerable peace of mind at times.
As mentioned above, I also have an I phone with a chartplotter app. and it is quite amazing. $5 I think it was and the charts are all free to download. You can enter waypoints, it gives the GPS coordinates of course, SOG, etc. I think I would prefer this option to even a small handheld GPS because it uses the actual NOAA charts rather than proprietary cartography (raster vs. vector). We use it as backup to the Garmin chartplotter and take it in the dink when exploring or fishing (useful as a depth indicator from the soundings and depth contours).
SV Laurie Anne
1988 Brewer 40 Pilothouse