Looking for recommendations for a handheld GPS. I am about to get my Hunter 170 and will be sailing it in an around Edgartown and Oak Bluffs. I will never be beyond site of land (unless Nantucket tempts me at some point). I have a Garmin eMap and charts which really seems like enough except it isn't waterproof. I could go cheap with an eTrex which is all I probably need. HOWEVER, I saw a GPSMap 478 today and love the charts, find function, tides, etc, etc but the price is way too high for my needs (~$900). It seems like true overkill. I could get a GPSMAP 76 with the Bluechart for my area, but you are already up to $400 or so.I know I can use it in my car, but both cars already have a GPS. So, any advice for me?