Thanks Neil.

My main problem is how to even get to the files that are loaded on the unit. I want to try to load maps to the internal memory or hard drive of the unit, but there is no USB port or ANY external port that is accessible if the unit is mounted in the dash of a boat. No USB ports.

Other than the SD card slot, any other ports are located on the back of the unit.

I figured that there "may" be a hidden menu accessed by pressing and holding a certain area of the touch screen the way you do with the automotive units.

But I just really don't know...... As I said, I don't even know if it's a hard drive or merely internal memory that holds the pre-loaded charts.

The unit supposedly has 64GB of factory memory, so I assume there isn't a hard drive, but rather all files are in onboard memory.

At this point in time, if you want to switch charts, you have to swap out SD cards for each chart/map.

Any suggestions or help ?