I would really like to make my own bathymetric map of my new 11-12 acre pond/lake. Anyone ever done this?

One should be able to accomplish this with a decent GPS unit, a depth finder and a boat. But how in the world would I combine and compile the data? Is there an easier way? Any depth finders that have the ability to generate a contour map over time (for instance from trolling the surface over time)?

I know I could hire someone to do this, but I would really like to do it myself as it seems like a fun project.

Anyone ever done or tried to do it? Any advice?

12 ac pond in NW Missouri. 28' max depth at full pool. Fish Present: LMB, BG, RES, YP, CC, WB, HSB, WE, BCP, WCP, GSH.