Hi. I'm new to this site though not to sea angling. My 19' boat is currently fitted with separate GPS and fishfinder but what I want is a unit which will plot the sea bed to create a 3D map built up over time as I cover the ground I fish on over and over again - so it has both GPS and sonar functions but the map building feature is the key thing. These units are commonplace on commercial fishing boats around here but when I last looked were too big and way too expensive. Hopefully they've now come withing reach of an ordinary guy with a hobby angling boat. I've not looked for one for a while - do any of you guys know what's out there, and can you recommend anything? Thanks!