Shakespere Galaxy 8 footer is one of the best and costs about $150 but i have communicated with others from center harbor to mouth of alton bay with it. My antenna is mounted to my roof and the tip is a total of about 14 feet off the water maybe 16. A good connection from your antenna wire to your connector plug is important. There are 2 you can get and they are easy to put on. 1 requires solder and the other is a pinch on. I know this may sound funny but i do better with the pinch on than the solder on. Grab 1 at a west marine, cut off your old 1 and follow directions for new 1 it is an easy way and cheap to check for a possible easy fix. I was having trouble and i did this and it was night and day i gained about 10 miles.
it's most likely your connection. i only have a 3' stainless whip right now and it's not even mounted in the new boat. right now it's laying down next to the drivers seat but could hear dave in center harbor today load and clear from harilla's ( not drilling any holes in the new boat until new 8' antenna arrives)