The best 20 bucks in all of fishing is an extra power cord for your chartplotter.
I just sat through the Cat video and followed along and got it all in my chartplotter at home.
No need to go to the boat to learn your electronics.
Great tip. Plugged mine into a battery charger on the kitchen table and had hrs of entertainment.It turns out that the first action recomended if the unit missfires is to unplug it and replug it in. It cleans the pin plug connections.