I have had enough Ranger 600 series boats through the years to know them inside and out. Many boat owners don't know their boats below the surface and that is a mistake that will eventually cost time and fish.
Whether money is no object or you're a working man like myself, once spring arrives you may have to wait weeks before you can get your rig into a boat dealer or marine mechanic. Add anywhere from a few days to a few weeks to get parts and you could easily miss a good portion of your season. Much of this can be eliminated by performing your own maintenance and intimately knowing your boat. Personally, I want to know what every wire is because on the waters I frequent, I can't afford to risk not knowing how to repair something that might be broken.
Something as simple as using a piece of duct tape folded over with a sharpie to mark what the wire is will do wonders when trying to diagnosis a problem or find that one wire that looks exactly like the others.
Another major issue in boats is moisture in your connections. Every year it causes tons of anglers to have issues with VHF radios, sonar/GPS units and even your main wiring. A simple fix is to use dialectic grease before making crimps and connections. The grease expands the connection area and acts as an insulator from moisture. Avoid cheap car wiring and use tinned copper to help prevent corrosion. Fittings that have heat shrink tubing or adhesive shrink tubing over the connections will keep you from being the guy that has the power flash on and off on his GPS every time you hit a wave.
A little extra care and better components will help insure your boat functions at top shape when you need it to.