My C 30 is a lil bigger & has a binnacle for the wheel to mount a GPS unit to. I have a Garmin 440S GPS -plotter unit which I think is a great unit for the money. I got mine with the optional depth sounder (which is what the S stands for). I have sailed in the Charlestown area many times, around Mt. Pleasant, Sullivans Island & Isle of Palms in your area. You need a good depth sounder, because there is a lot of sholing & slack water in that area. But its also great sailing in Charlestown harbor. I have a back up Garmin handheld 76 GPS unit which they now make in color, which I'm sure must be easier to read then my old black & white model. The Garmin 76cx is about $200, & the 440S is around $400. I saw it recently on sale at W. Marine. But you have to pay extra for the sounder attachment. I like having the built in sounder, as the display show all of you pertinent info in one place. Good luck & enjoy seeing the annual Charlestown race week.