by Bill Morris Arriving at our next port successfully depends, in great measure, on properly functioning electronic navigation and communication systems. And maintaining those systems in tip-top condition requires dependable test equipment, most notably a high-quality multimeter. Surprisingly, many cruising vessels carry no more than a current tester consisting of two wires and a sealed lightbulb to demonstrate the presence of current — how much is anyone’s guess. Some skippers rely on a small, inexpensive battery tester with color bands: green for good, yellow for so-so and red for replace. Properly prepared skippers, on the other hand, equip their vessels…