Enlarged extract from the sectional chart showing my over-water crossing from West Palm Beach to Freeport. The green lines are the track lines I followed outbound from West Palm Beach (PBI) to Freeport (MYGF) although I re-planned the return to go direct to Fort Pierce (KFPR). The dark area in the middle is where the two scans of the map differed in brightness!
The green bar on the track to Freeport is the 20 nautical mile reporting point which can be gleaned from the Distance Measuring Equipment (DME) on-board the aircraft. TOC on the return track marks "Top of Climb" (we were cleared to 11500') which was probably a bit further along!

NOT FOR NAVIGATION -- THIS IMAGE IS PURELY FOR REPRESENTATIONAL PURPOSES.
If you want to fly the route, it is your legal responsibility as Pilot-in-Command to obtain and familiarise yourself with the newest sectional chart.